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Sample records for heating effects network

  1. The simplicity of fractal-like flow networks for effective heat and mass transport

    SciTech Connect

    Pence, Deborah

    2010-05-15

    A variety of applications using disk-shaped fractal-like flow networks and the status of one and two-dimensional predictive models for these applications are summarized. Applications discussed include single-phase and two-phase heat sinks and heat exchangers, two-phase flow separators, desorbers, and passive micromixers. Advantages of using these fractal-like flow networks versus parallel-flow networks include lower pressure drop, lower maximum wall temperature, inlet plenum symmetry, alternate flow paths, and pressure recovery at the bifurcation. The compact nature of microscale fractal-like branching heat exchangers makes them ideal for modularity. Differences between fractal-like and constructal approaches applied to disk-shaped heat sink designs are highlighted, and the importance of including geometric constraints, including fabrication constraints, in flow network design optimization is discussed. Finally, a simple pencil and paper procedure for designing single-phase heat sinks with fractal-like flow networks based solely on geometric constraints is outlined. Benefit-to-cost ratios resulting from geometric-based designs are compared with those from flow networks determined using multivariable optimization. Results from the two network designs are within 11%. (author)

  2. Effective design of profiling float network for oceanic heat-content monitoring.

    PubMed

    Masuda, Shuhei; Hosoda, Shigeki

    2014-01-01

    Schemes for optimizing ocean observation programs are presently the subject of increased interest since in principle they should lead to the improved understanding of the dynamical state of the ocean that is required within the present regime of climate change. Here we use an adjoint sensitivity analysis together with a four-dimensional fluctuating oceanic current system to identify key regions for intensive monitoring by drifting profiling float. In this way we aim to maximize observational efficiency. As a scientific benchmark for the validity of our approach, we have attempted to define the ambient sensitivity of the oceanic heat content to a subtle change in water temperature within the Pacific Basin. We focus on the interannual to multidecadal variations in particular. As a result, sensitivity signals reflecting changes in heat content exhibit a characteristic pattern in the three-dimensional continuum and have drastic temporal changes. This implies that the key regions will depend greatly on the operational timeframe of the observing system. We demonstrate a more effective geographic deployment strategy for the profiling floats monitoring changes in the oceanic heat content on a decadal timescale. PMID:24723802

  3. Effective Design of Profiling Float Network for Oceanic Heat-Content Monitoring

    PubMed Central

    Hosoda, Shigeki

    2014-01-01

    Schemes for optimizing ocean observation programs are presently the subject of increased interest since in principle they should lead to the improved understanding of the dynamical state of the ocean that is required within the present regime of climate change. Here we use an adjoint sensitivity analysis together with a four-dimensional fluctuating oceanic current system to identify key regions for intensive monitoring by drifting profiling float. In this way we aim to maximize observational efficiency. As a scientific benchmark for the validity of our approach, we have attempted to define the ambient sensitivity of the oceanic heat content to a subtle change in water temperature within the Pacific Basin. We focus on the interannual to multidecadal variations in particular. As a result, sensitivity signals reflecting changes in heat content exhibit a characteristic pattern in the three-dimensional continuum and have drastic temporal changes. This implies that the key regions will depend greatly on the operational timeframe of the observing system. We demonstrate a more effective geographic deployment strategy for the profiling floats monitoring changes in the oceanic heat content on a decadal timescale. PMID:24723802

  4. Numerical Investigation of the effect of adiabatic section location on thermal performance of a heat pipe network with the application in thermal energy storage systems

    NASA Astrophysics Data System (ADS)

    Mahdavi, Mahboobe; Tiari, Saeed; Qiu, Songgang

    2015-11-01

    Latent heat thermal energy storage systems benefits from high energy density and isothermal storing process. However, the low thermal conductivity of the phase change material leads to prolong the melting or solidification time. Using a passive device such as heat pipes is required to enhance the heat transfer and to improve the efficiency of the system. In the present work, the performance of a heat pipe network specifically designed for a thermal energy storage system is studied numerically. The network includes a primary heat pipe, which transfers heat received from solar receiver to the heat engine. The excess heat is simultaneously delivered to charge the phase change material via secondary heat pipes. The primary heat pipe composed of a disk shape evaporator, an adiabatic section and a disk shape condenser. The adiabatic section can be either located at the center or positioned outward to the surrounding of the container. Here, the effect of adiabatic section position on thermal performance of the system is investigated. It was concluded that displacing the adiabatic section outwards dramatically increases the average temperatures of the condensers and reduces the thermal resistance of heat pipes.

  5. Physical explosion analysis in heat exchanger network design

    NASA Astrophysics Data System (ADS)

    Pasha, M.; Zaini, D.; Shariff, A. M.

    2016-06-01

    The failure of shell and tube heat exchangers is being extensively experienced by the chemical process industries. This failure can create a loss of production for long time duration. Moreover, loss of containment through heat exchanger could potentially lead to a credible event such as fire, explosion and toxic release. There is a need to analyse the possible worst case effect originated from the loss of containment of the heat exchanger at the early design stage. Physical explosion analysis during the heat exchanger network design is presented in this work. Baker and Prugh explosion models are deployed for assessing the explosion effect. Microsoft Excel integrated with process design simulator through object linking and embedded (OLE) automation for this analysis. Aspen HYSYS V (8.0) used as a simulation platform in this work. A typical heat exchanger network of steam reforming and shift conversion process was presented as a case study. It is investigated from this analysis that overpressure generated from the physical explosion of each heat exchanger can be estimated in a more precise manner by using Prugh model. The present work could potentially assist the design engineer to identify the critical heat exchanger in the network at the preliminary design stage.

  6. Global optimization algorithm for heat exchanger networks

    SciTech Connect

    Quesada, I.; Grossmann, I.E. )

    1993-03-01

    This paper deals with the global optimization of heat exchanger networks with fixed topology. It is shown that if linear area cost functions are assumed, as well as arithmetic mean driving force temperature differences in networks with isothermal mixing, the corresponding nonlinear programming (NLP) optimization problem involves linear constraints and a sum of linear fractional functions in the objective which are nonconvex. A rigorous algorithm is proposed that is based on a convex NLP underestimator that involves linear and nonlinear estimators for fractional and bilinear terms which provide a tight lower bound to the global optimum. This NLP problem is used within a spatial branch and bound method for which branching rules are given. Basic properties of the proposed method are presented, and its application is illustrated with several example problems. The results show that the proposed method only requires few nodes in the branch and bound search.

  7. Heat diffusion: Thermodynamic depth complexity of networks

    NASA Astrophysics Data System (ADS)

    Escolano, Francisco; Hancock, Edwin R.; Lozano, Miguel A.

    2012-03-01

    In this paper we use the Birkhoff-von Neumann decomposition of the diffusion kernel to compute a polytopal measure of graph complexity. We decompose the diffusion kernel into a series of weighted Birkhoff combinations and compute the entropy associated with the weighting proportions (polytopal complexity). The maximum entropy Birkhoff combination can be expressed in terms of matrix permanents. This allows us to introduce a phase-transition principle that links our definition of polytopal complexity to the heat flowing through the network at a given diffusion time. The result is an efficiently computed complexity measure, which we refer to as flow complexity. Moreover, the flow complexity measure allows us to analyze graphs and networks in terms of the thermodynamic depth. We compare our method with three alternative methods described in the literature (Estrada's heterogeneity index, the Laplacian energy, and the von Neumann entropy). Our study is based on 217 protein-protein interaction (PPI) networks including histidine kinases from several species of bacteria. We find a correlation between structural complexity and phylogeny (more evolved species have statistically more complex PPIs). Although our methods outperform the alternatives, we find similarities with Estrada's heterogeneity index in terms of network size independence and predictive power.

  8. Neural network analysis on the effect of heat fluxes on greenhouse gas emissions from anaerobic swine waste treatment lagoon

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In this study, we examined the various meteorological factors (i.e., air temperatures, solar radiation, and heat fluxes) that potentially affect greenhouse gas (GHG) emissions from swine waste lagoon. GHG concentrations (methane, carbon dioxide, and nitrous oxide) were monitored using a photoacous...

  9. The effect of heat fluxes on ammonia emission from swine waste lagoon based on neural network analyses

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Understanding factors that affect ammonia emissions from swine waste lagoons or any animal waste receptacles is a necessary first step in deploying potential remediation options. In this study, we examined the various meteorological factors (i.e., air temperatures, solar radiation, and heat fluxes)...

  10. Are heat warning systems effective?

    PubMed Central

    2013-01-01

    Heatwaves are associated with significant health risks particularly among vulnerable groups. To minimize these risks, heat warning systems have been implemented. The question therefore is how effective these systems are in saving lives and reducing heat-related harm. We systematically searched and reviewed 15 studies which examined this. Six studies asserted that fewer people died of excessive heat after the implementation of heat warning systems. Demand for ambulance decreased following the implementation of these systems. One study also estimated the costs of running heat warning systems at US$210,000 compared to the US$468 million benefits of saving 117 lives. The remaining eight studies investigated people’s response to heat warning systems and taking appropriate actions against heat harms. Perceived threat of heat dangers emerged as the main factor related to heeding the warnings and taking proper actions. However, barriers, such as costs of running air-conditioners, were of significant concern, particularly to the poor. The weight of the evidence suggests that heat warning systems are effective in reducing mortality and, potentially, morbidity. However, their effectiveness may be mediated by cognitive, emotive and socio-demographic characteristics. More research is urgently required into the cost-effectiveness of heat warning systems’ measures and improving the utilization of the services. PMID:23561265

  11. Tool Steel Heat Treatment Optimization Using Neural Network Modeling

    NASA Astrophysics Data System (ADS)

    Podgornik, Bojan; Belič, Igor; Leskovšek, Vojteh; Godec, Matjaz

    2016-08-01

    Optimization of tool steel properties and corresponding heat treatment is mainly based on trial and error approach, which requires tremendous experimental work and resources. Therefore, there is a huge need for tools allowing prediction of mechanical properties of tool steels as a function of composition and heat treatment process variables. The aim of the present work was to explore the potential and possibilities of artificial neural network-based modeling to select and optimize vacuum heat treatment conditions depending on the hot work tool steel composition and required properties. In the current case training of the feedforward neural network with error backpropagation training scheme and four layers of neurons (8-20-20-2) scheme was based on the experimentally obtained tempering diagrams for ten different hot work tool steel compositions and at least two austenitizing temperatures. Results show that this type of modeling can be successfully used for detailed and multifunctional analysis of different influential parameters as well as to optimize heat treatment process of hot work tool steels depending on the composition. In terms of composition, V was found as the most beneficial alloying element increasing hardness and fracture toughness of hot work tool steel; Si, Mn, and Cr increase hardness but lead to reduced fracture toughness, while Mo has the opposite effect. Optimum concentration providing high KIc/HRC ratios would include 0.75 pct Si, 0.4 pct Mn, 5.1 pct Cr, 1.5 pct Mo, and 0.5 pct V, with the optimum heat treatment performed at lower austenitizing and intermediate tempering temperatures.

  12. Tool Steel Heat Treatment Optimization Using Neural Network Modeling

    NASA Astrophysics Data System (ADS)

    Podgornik, Bojan; Belič, Igor; Leskovšek, Vojteh; Godec, Matjaz

    2016-11-01

    Optimization of tool steel properties and corresponding heat treatment is mainly based on trial and error approach, which requires tremendous experimental work and resources. Therefore, there is a huge need for tools allowing prediction of mechanical properties of tool steels as a function of composition and heat treatment process variables. The aim of the present work was to explore the potential and possibilities of artificial neural network-based modeling to select and optimize vacuum heat treatment conditions depending on the hot work tool steel composition and required properties. In the current case training of the feedforward neural network with error backpropagation training scheme and four layers of neurons (8-20-20-2) scheme was based on the experimentally obtained tempering diagrams for ten different hot work tool steel compositions and at least two austenitizing temperatures. Results show that this type of modeling can be successfully used for detailed and multifunctional analysis of different influential parameters as well as to optimize heat treatment process of hot work tool steels depending on the composition. In terms of composition, V was found as the most beneficial alloying element increasing hardness and fracture toughness of hot work tool steel; Si, Mn, and Cr increase hardness but lead to reduced fracture toughness, while Mo has the opposite effect. Optimum concentration providing high KIc/HRC ratios would include 0.75 pct Si, 0.4 pct Mn, 5.1 pct Cr, 1.5 pct Mo, and 0.5 pct V, with the optimum heat treatment performed at lower austenitizing and intermediate tempering temperatures.

  13. The NSF-RCN Urban Heat Island Network

    NASA Astrophysics Data System (ADS)

    Twine, T. E.; Snyder, P. K.; Hamilton, P.; Shepherd, M.; Stone, B., Jr.

    2015-12-01

    In much of the world cities are warming at twice the rate of outlying rural areas. The frequency of urban heat waves is projected to increase with climate change through the 21st century. Addressing the economic, environmental, and human costs of urban heat islands requires a better understanding of their behavior from many disciplinary perspectives. The goal of this four-year Urban Heat Island Network is to (1) bring together scientists studying the causes and impacts of urban warming, (2) advance multidisciplinary understanding of urban heat islands, (3) examine how they can be ameliorated through engineering and design practices, and (4) share these new insights with a wide array of stakeholders responsible for managing urban warming to reduce their health, economic, and environmental impacts. The NSF-RCN Urban Heat Island Network involves atmospheric scientists, engineers, architects, landscape designers, urban planners, public health experts, and education and outreach experts, who will share knowledge, evaluate research directions, and communicate knowledge and research recommendations to the larger research community as well as stakeholders engaged in developing strategies to adapt to and mitigate urban warming. The first Urban Climate Institute was held in Saint Paul, MN in July 2013 and focused on the characteristics of urban heat islands. Scientists engaged with local practitioners to improve communication pathways surrounding issues of understanding, adapting to, and mitigating urban warming. The second Urban Climate Institute was held in Atlanta, Georgia in July 2014 and focused on urban warming and public health. The third Urban Climate Institute was held in Athens, GA in July 2015 and focused on urban warming and the role of the built environment. Scientists and practitioners discussed strategies for mitigation and adaptation. Evaluation experts at the Science Museum of Minnesota have extensively evaluated the Institutes to inform other research

  14. Super-Joule heating in graphene and silver nanowire network

    NASA Astrophysics Data System (ADS)

    Maize, Kerry; Das, Suprem R.; Sadeque, Sajia; Mohammed, Amr M. S.; Shakouri, Ali; Janes, David B.; Alam, Muhammad A.

    2015-04-01

    Transistors, sensors, and transparent conductors based on randomly assembled nanowire networks rely on multi-component percolation for unique and distinctive applications in flexible electronics, biochemical sensing, and solar cells. While conduction models for 1-D and 1-D/2-D networks have been developed, typically assuming linear electronic transport and self-heating, the model has not been validated by direct high-resolution characterization of coupled electronic pathways and thermal response. In this letter, we show the occurrence of nonlinear "super-Joule" self-heating at the transport bottlenecks in networks of silver nanowires and silver nanowire/single layer graphene hybrid using high resolution thermoreflectance (TR) imaging. TR images at the microscopic self-heating hotspots within nanowire network and nanowire/graphene hybrid network devices with submicron spatial resolution are used to infer electrical current pathways. The results encourage a fundamental reevaluation of transport models for network-based percolating conductors.

  15. Super-Joule heating in graphene and silver nanowire network

    SciTech Connect

    Maize, Kerry; Das, Suprem R.; Sadeque, Sajia; Mohammed, Amr M. S.; Shakouri, Ali E-mail: alam@purdue.edu; Janes, David B.; Alam, Muhammad A. E-mail: alam@purdue.edu

    2015-04-06

    Transistors, sensors, and transparent conductors based on randomly assembled nanowire networks rely on multi-component percolation for unique and distinctive applications in flexible electronics, biochemical sensing, and solar cells. While conduction models for 1-D and 1-D/2-D networks have been developed, typically assuming linear electronic transport and self-heating, the model has not been validated by direct high-resolution characterization of coupled electronic pathways and thermal response. In this letter, we show the occurrence of nonlinear “super-Joule” self-heating at the transport bottlenecks in networks of silver nanowires and silver nanowire/single layer graphene hybrid using high resolution thermoreflectance (TR) imaging. TR images at the microscopic self-heating hotspots within nanowire network and nanowire/graphene hybrid network devices with submicron spatial resolution are used to infer electrical current pathways. The results encourage a fundamental reevaluation of transport models for network-based percolating conductors.

  16. Use of the exergy concept for design improvement of heat exchangers and heat exchanger networks

    SciTech Connect

    Ranasinghe, J.

    1989-01-01

    The second law of thermodynamics, through the exergy concept, allows us to quantify and rationally coat the consumption of exergy (irreversibility) used to drive the heat exchange process and the effluent losses of exergy in a heat exchanger. For systems with a network of heat exchangers, the exergy concept recognizes that properly integrated heat pumps reduce the heat transfer irreversibility; this results in reduced utility consumption. Heat engines properly integrated in heat exchanger networks also recover a fraction of the thermodynamic potential destroyed during the heat transfer process and generate power at very high efficiencies. Heat exchanger design conditions are characterized and potential trade-off options discussed. A modification to the irreversibility minimization method is proposed next, and the proposed method gives more realistic guide posts for heat exchangers, compared to the corresponding guide posts obtained from present methods. This thesis also proposes a method to obtain the irreversibility cost coefficients for heat exchangers residing in complex systems. The application of the modified irreversibility method proposed here, and the thermoeconomic method, are illustrated by optimizing an emerging technology ceramic heat exchanger residing in a complex power plant. A method based on the exergy concept is developed to recognize the potential for improvement of processes with process integrated heat pumps and heat engines. Once potential processes have been identified, economically optimum load and level of integration have to be determined. The method of formulating the economic optimization problem is presented, and bounds for some design variables are finally developed.

  17. Teaching Heat Exchanger Network Synthesis Using Interactive Microcomputer Graphics.

    ERIC Educational Resources Information Center

    Dixon, Anthony G.

    1987-01-01

    Describes the Heat Exchanger Network Synthesis (HENS) program used at Worcester Polytechnic Institute (Massachusetts) as an aid to teaching the energy integration step in process design. Focuses on the benefits of the computer graphics used in the program to increase the speed of generating and changing networks. (TW)

  18. Network Coronal Bright Points: Coronal Heating Concentrations Found in the Solar Magnetic Network

    NASA Technical Reports Server (NTRS)

    Falconer, D. A.; Moore, R. L.; Porter, J. G.; Hathaway, D.

    1997-01-01

    We examine the magnetic origins of coronal heating in quiet regions by combining SOHO/EIT Fe XII coronal images and Kitt Peak magnetograms. Spatial filtering of the coronal images shows a network of enhanced structures on the scale of the magnetic network in quiet regions. Superposition of the filtered coronal images on maps of the magnetic network extracted from the magnetograms shows that the coronal network does indeed trace and stem from the magnetic network. Network coronal bright points, the brightest features in the network lanes, are found to have a highly significant (8 sigma above random chance) coincidence with polarity dividing lines (neutral lines) in the network, and are often at the feet of enhanced coronal structures that stem from the network and reach out over the cell interiors. These results indicate that, similar to the close linkage of neutral-line core fields with coronal heating in active regions, low-lying core fields encasing neutral lines in the magnetic network often drive noticeable coronal heating both within themselves (the network coronal bright points) and on more extended fields lines rooted around them. This behavior favors the possibility that active core fields in the network are the main drivers of the heating of the bulk of the quiet corona, on scales much larger than the network lanes and cells.

  19. Network Coronal Bright Points: Coronal Heating Concentrations Found in the Solar Magnetic Network

    NASA Technical Reports Server (NTRS)

    Falconer, D. A.; Moore, R. L.; Porter, J. G.; Hathaway, D. H.

    1998-01-01

    We examine the magnetic origins of coronal heating in quiet regions by combining SOHO/EIT Fe xii coronal images and Kitt Peak magnetograms. Spatial filtering of the coronal images shows a network of enhanced structures on the scale of the magnetic network in quiet regions. Superposition of the filtered coronal images on maps of the magnetic network extracted from the magnetograms shows that the coronal network does indeed trace and stem from the magnetic network. Network coronal bright points, the brightest features in the network lanes, are found to have a highly significant coincidence with polarity dividing lines (neutral lines) in the network and are often at the feet of enhanced coronal structures that stem from the network and reach out over the cell interiors. These results indicate that, similar to the close linkage of neutral-line core fields with coronal heating in active regions (shown in previous work), low-lying core fields encasing neutral lines in the magnetic network often drive noticeable coronal heating both within themselves (the network coronal bright points) and on more extended field lines rooted around them. This behavior favors the possibility that active core fields in the network are the main drivers of the heating of the bulk of the quiet corona, on scales much larger than the network lanes and cells.

  20. Back propagation neural network based control for the heating system of a polysilicon reduction furnace.

    PubMed

    Cheng, Yuhua; Chen, Kai; Bai, Libing; Dai, Meizhi

    2013-12-01

    In this paper, the Back Propagation (BP) neural network based control strategy is proposed for the heating system of a polysilicon reduction furnace. It is applied to obtain the control signal I(d), which is used to adjust the heating power through operations of the silicon core temperature, furnace temperature, silicon core voltage, and resistance of the current control cycle. With the control signal I(d) the polycrystalline silicon can be heated from room temperature to the required temperature smoothly and steadily. The proposed BP network applied in this paper can obtain the accurate control signal I(d) and achieve the precise control purpose. This paper presents the principle of the BP network and demonstrates the effectiveness of the BP network in the heating system of a polysilicon reduction furnace by combining the simulation analysis with experimental results.

  1. Characterising brain network topologies: A dynamic analysis approach using heat kernels.

    PubMed

    Chung, A W; Schirmer, M D; Krishnan, M L; Ball, G; Aljabar, P; Edwards, A D; Montana, G

    2016-11-01

    Network theory provides a principled abstraction of the human brain: reducing a complex system into a simpler representation from which to investigate brain organisation. Recent advancement in the neuroimaging field is towards representing brain connectivity as a dynamic process in order to gain a deeper understanding of how the brain is organised for information transport. In this paper we propose a network modelling approach based on the heat kernel to capture the process of heat diffusion in complex networks. By applying the heat kernel to structural brain networks, we define new features which quantify change in heat propagation. Identifying suitable features which can classify networks between cohorts is useful towards understanding the effect of disease on brain architecture. We demonstrate the discriminative power of heat kernel features in both synthetic and clinical preterm data. By generating an extensive range of synthetic networks with varying density and randomisation, we investigate heat diffusion in relation to changes in network topology. We demonstrate that our proposed features provide a metric of network efficiency and may be indicative of organisational principles commonly associated with, for example, small-world architecture. In addition, we show the potential of these features to characterise and classify between network topologies. We further demonstrate our methodology in a clinical setting by applying it to a large cohort of preterm babies scanned at term equivalent age from which diffusion networks were computed. We show that our heat kernel features are able to successfully predict motor function measured at two years of age (sensitivity, specificity, F-score, accuracy = 75.0, 82.5, 78.6, and 82.3%, respectively).

  2. Characterising brain network topologies: A dynamic analysis approach using heat kernels.

    PubMed

    Chung, A W; Schirmer, M D; Krishnan, M L; Ball, G; Aljabar, P; Edwards, A D; Montana, G

    2016-11-01

    Network theory provides a principled abstraction of the human brain: reducing a complex system into a simpler representation from which to investigate brain organisation. Recent advancement in the neuroimaging field is towards representing brain connectivity as a dynamic process in order to gain a deeper understanding of how the brain is organised for information transport. In this paper we propose a network modelling approach based on the heat kernel to capture the process of heat diffusion in complex networks. By applying the heat kernel to structural brain networks, we define new features which quantify change in heat propagation. Identifying suitable features which can classify networks between cohorts is useful towards understanding the effect of disease on brain architecture. We demonstrate the discriminative power of heat kernel features in both synthetic and clinical preterm data. By generating an extensive range of synthetic networks with varying density and randomisation, we investigate heat diffusion in relation to changes in network topology. We demonstrate that our proposed features provide a metric of network efficiency and may be indicative of organisational principles commonly associated with, for example, small-world architecture. In addition, we show the potential of these features to characterise and classify between network topologies. We further demonstrate our methodology in a clinical setting by applying it to a large cohort of preterm babies scanned at term equivalent age from which diffusion networks were computed. We show that our heat kernel features are able to successfully predict motor function measured at two years of age (sensitivity, specificity, F-score, accuracy = 75.0, 82.5, 78.6, and 82.3%, respectively). PMID:27421183

  3. Heating Effect On Serpentine Jades

    NASA Astrophysics Data System (ADS)

    Chen, T.-H.; Menu, M.

    2010-08-01

    Besides nephrite, serpentine is also frequently employed as a jade material in China since the Neolithic period. Translucent or opaque, serpentine presents diverse colors, including yellow-green, green, dark green, and tan, which are related to its chemical composition and occasionally to its associated sub-major minerals. Serpentine could be subjected to color change due to secondary alterations or weathering. In this study, we mainly focus on the heating effect on serpentine, as some ancient serpentine jades may have been exposed to heat for some different reasons, such as carving, funeral ceremony or imitating. A series of non-heated and heat-treated raw serpentine jades are examined using Raman spectroscopy and other complementary methods. The subtle change of molecular structure and color of serpentine due to the heat treatment is reported in detail.

  4. A performance data network for solar process heat systems

    SciTech Connect

    Barker, G.; Hale, M.J.

    1996-03-01

    A solar process heat (SPH) data network has been developed to access remote-site performance data from operational solar heat systems. Each SPH system in the data network is outfitted with monitoring equipment and a datalogger. The datalogger is accessed via modem from the data network computer at the National Renewable Energy Laboratory (NREL). The dataloggers collect both ten-minute and hourly data and download it to the data network every 24-hours for archiving, processing, and plotting. The system data collected includes energy delivered (fluid temperatures and flow rates) and site meteorological conditions, such as solar insolation and ambient temperature. The SPH performance data network was created for collecting performance data from SPH systems that are serving in industrial applications or from systems using technologies that show promise for industrial applications. The network will be used to identify areas of SPH technology needing further development, to correlate computer models with actual performance, and to improve the credibility of SPH technology. The SPH data network also provides a centralized bank of user-friendly performance data that will give prospective SPH users an indication of how actual systems perform. There are currently three systems being monitored and archived under the SPH data network: two are parabolic trough systems and the third is a flat-plate system. The two trough systems both heat water for prisons; the hot water is used for personal hygiene, kitchen operations, and laundry. The flat plate system heats water for meat processing at a slaughter house. We plan to connect another parabolic trough system to the network during the first months of 1996. We continue to look for good examples of systems using other types of collector technologies and systems serving new applications (such as absorption chilling) to include in the SPH performance data network.

  5. Two-Dimensional Heat Transfer in a Heterogeneous Fracture Network

    NASA Astrophysics Data System (ADS)

    Gisladottir, V. R.; Roubinet, D.; Tartakovsky, D. M.

    2015-12-01

    Geothermal energy harvesting requires extraction and injection of geothermal fluid. Doing so in an optimal way requires a quantitative understanding of site-specific heat transfer between geothermal fluid and the ambient rock. We develop a heat transfer particle-tracking approach to model that interaction. Fracture-network models of heat transfer in fractured rock explicitly account for the presence of individual fractures, ambient rock matrix, and fracture-matrix interfaces. Computational domains of such models span the meter scale, whereas fracture apertures are on the millimeter scale. The computations needed to model these multi-scale phenomenon can be prohibitively expensive, even for methods using nonuniform meshes. Our approach appreciably decreases the computational costs. Current particle-tracking methods usually assume both infinite matrix and one-dimensional (1D) heat transfer in the matrix blocks. They rely on 1D analytical solutions for heat transfer in a single fracture, which can lead to large predictive errors. Our two-dimensional (2D) heat transfer simulation algorithm is mesh-free and takes into account both longitudinal and transversal heat conduction in the matrix. It uses a probabilistic model to transfer particle to the appropriate neighboring fracture unless it returns to the fracture of origin or remains in the matrix. We use this approach to look at the impact of a fracture-network topology (e.g. the importance of smaller scale fractures), as well as the matrix block distribution on the heat transport in heterogeneous fractured rocks.

  6. The NSF-RCN Urban Heat Island Network

    NASA Astrophysics Data System (ADS)

    Twine, T. E.; Snyder, P. K.; Hamilton, P.; Shepherd, M.; Stone, B., Jr.

    2014-12-01

    In much of the world cities are warming at twice the rate of outlying rural areas. The frequency of urban heat waves is projected to increase with climate change through the 21stcentury. Addressing the economic, environmental, and human costs of urban heat islands requires a better understanding of their behavior from many disciplinary perspectives. The goal of this four-year Urban Heat Island Network is to (1) bring together scientists studying the causes and impacts of urban warming, (2) advance multidisciplinary understanding of urban heat islands, (3) examine how they can be ameliorated through engineering and design practices, and (4) share these new insights with a wide array of stakeholders responsible for managing urban warming to reduce their health, economic, and environmental impacts. The Urban Heat Island Network involves atmospheric scientists, engineers, architects, landscape designers, urban planners, public health experts, and education and outreach experts, who will share knowledge, evaluate research directions, and communicate knowledge and research recommendations to the larger research community as well as stakeholders engaged in developing strategies to adapt to and mitigate urban warming. The first Urban Climate Institute was held in Saint Paul, Minnesota in July 2013 and focused on the characteristics of urban heat islands. Scientists engaged with local practitioners to improve communication pathways surrounding issues of understanding, adapting to, and mitigating urban warming. The second Urban Climate Institute was held in Atlanta, Georgia in July 2014 and focused on urban warming and public health. Scientists discussed the state of the science on urban modeling, heat adaptation, air pollution, and infectious disease. Practitioners informed participants on emergency response methods and protocols related to heat and other extreme weather events. Evaluation experts at the Science Museum of Minnesota have extensively evaluated both Institutes

  7. Latent Heat and Sensible Heat Fluxes Simulation in Maize Using Artificial Neural Networks

    NASA Astrophysics Data System (ADS)

    Safa, B.

    2015-12-01

    Latent Heat (LE) and Sensible Heat (H) flux are two major components of the energy balance at the earth's surface which play important roles in the water cycle and global warming. There are various methods for their estimation or measurement. Eddy covariance is a direct and accurate technique for their measurement. Some limitations lead to prevention of the extensive use of the eddy covariance technique. Therefore, simulation approaches can be utilized for their estimation. ANNs are the information processing systems, which can inspect the empirical data and investigate the relations (hidden rules) among them, and then make the network structure. In this study, multi-layer perceptron neural network trained by the steepest descent Back-Propagation (BP) algorithm was tested to simulate LE and H flux above two maize sites (rain-fed & irrigated) near Mead, Nebraska. Network training and testing was fulfilled using hourly data of including year, local time of day (DTime), leaf area index (LAI), soil water content (SWC) in 10 and 25 cm depths, soil temperature (Ts) in 10 cm depth, air temperature (Ta), vapor pressure deficit (VPD), wind speed (WS), irrigation and precipitation (P), net radiation (Rn), and the fraction of incoming Photosynthetically Active Radiation (PAR) absorbed by the canopy (fPAR), which were selected from days of year (DOY) 169 to 222 for 2001, 2003, 2005, 2007, and 2009. The results showed high correlation between actual and estimated data; the R² values for LE flux in irrigated and rain-fed sites were 0.9576, and 0.9642; and for H flux 0.8001, and 0.8478, respectively. Furthermore, the RMSE values ranged from 0.0580 to 0.0721 W/m² for LE flux and from 0.0824 to 0.0863 W/m² for H flux. In addition, the sensitivity of the fluxes with respect to each input was analyzed over the growth stages. Thus, the most powerful effects among the inputs for LE flux were identified net radiation, leaf area index, vapor pressure deficit, wind speed, and for H

  8. Incorporation of Condensation Heat Transfer in a Flow Network Code

    NASA Technical Reports Server (NTRS)

    Anthony, Miranda; Majumdar, Alok; McConnaughey, Paul K. (Technical Monitor)

    2001-01-01

    In this paper we have investigated the condensation of water vapor in a short tube. A numerical model of condensation heat transfer was incorporated in a flow network code. The flow network code that we have used in this paper is Generalized Fluid System Simulation Program (GFSSP). GFSSP is a finite volume based flow network code. Four different condensation models were presented in the paper. Soliman's correlation has been found to be the most stable in low flow rates which is of particular interest in this application. Another highlight of this investigation is conjugate or coupled heat transfer between solid or fluid. This work was done in support of NASA's International Space Station program.

  9. Experimental Study of Heat Transport in Fractured Network

    NASA Astrophysics Data System (ADS)

    Pastore, Nicola; Cherubini, Claudia; Giasi, Concetta I.; Allegretti, Nicoletta M.; Redondo, Jose M.; Tarquis, Ana Maria

    2015-04-01

    Fractured rocks play an important role in transport of natural resources or contaminants transport through subsurface systems. In recent years, interest has grown in investigating heat transport by means of tracer tests, driven by the important current development of geothermal applications. In literature different methods are available for predicting thermal breakthrough in fractured reservoirs based on the information coming from tracer tests. Geothermal energy is one of the largest sources of renewable energies that are extracted from the earth. The growing interest in this new energy source has stimulated attempts to develop methods and technologies for extracting energy also from ground resource at low temperature. An example is the exploitation of low enthalpy geothermal energy that can be obtained at any place with the aid of ground-source heat pump system from the soil, rock and groundwater. In such geothermal systems the fluid movement and thermal behavior in the fractured porous media is very important and critical. Existing theory of fluid flow and heat transport through porous media is of limited usefulness when applied to fractured rocks. Many field and laboratory tracer tests in fractured media show that fracture -matrix exchange is more significant for heat than mass tracers, thus thermal breakthrough curves (BTCs) are strongly controlled by matrix thermal diffusivity. In this study the behaviour of heat transport in a fractured network at bench scale has been investigated. Heat tracer tests on an artificially created fractured rock sample have been carried out. The observed thermal BTCs obtained with six thermocouple probes located at different locations in the fractured medium have been modeled with the Explicit Network Model (ENM) based an adaptation of Tang's solution for solute transport in a semi-infinite single fracture embedded in a porous matrix. The ENM model is able to represent the behavior of observed heat transport except where the

  10. Inverse Identification of Temperature-Dependent Volumetric Heat Capacity by Neural Networks

    NASA Astrophysics Data System (ADS)

    Czél, Balázs; Woodbury, Keith A.; Gróf, Gyula

    2013-02-01

    An artificial neural network (NN)-based solution of the inverse heat conduction problem of identifying the temperature-dependent volumetric heat capacity function of a solid material is presented in this paper. The inverse problem was defined according to the evaluation of the BICOND thermophysical property measurement method. The volumetric heat capacity versus temperature function is to be determined using the measured transient temperature history of a single sensor. In this study, noiseless and noisy artificial measurements were generated by the numerical solution of the corresponding direct heat conduction problem. The inverse problem was solved by back-propagation and radial basis function type neural networks applying the whole history mapping approach. The numerical tests included the comparison of two different data representations of the network inputs (i.e., temperature vs. time and time vs. temperature) and accuracy analysis of the two network types with noiseless and noisy inputs. Based on the results presented, it can be stated that feed-forward NNs are powerful tools in a non-iterative solution of function estimation inverse heat conduction problems and they are likely to be very effective in evaluation of real measured temperature histories to determine the volumetric heat capacity as an arbitrary function of temperature.

  11. Analytic solution for heat flow through a general harmonic network.

    PubMed

    Freitas, Nahuel; Paz, Juan Pablo

    2014-10-01

    We present an analytic expression for the heat current through a general harmonic network coupled with Ohmic reservoirs. We use a method that enables us to express the stationary state of the network in terms of the eigenvectors and eigenvalues of a generalized cubic eigenvalue problem. In this way, we obtain exact formulas for the heat current and the local temperature inside the network. Our method does not rely on the usual assumptions of weak coupling to the environments or on the existence of an infinite cutoff in the environmental spectral densities. We use this method to study nonequilibrium processes without the weak coupling and Markovian approximations. As a first application of our method, we revisit the problem of heat conduction in two- and three-dimensional crystals with binary mass disorder. We complement previous results showing that for small systems the scaling of the heat current with the system size greatly depends on the strength of the interaction between system and reservoirs. This somewhat counterintuitive result seems not to have been noticed before.

  12. Coronal Heating and the Magnetic Flux Content of the Network

    NASA Technical Reports Server (NTRS)

    Falconer, D. A.; Moore, R. L.; Porter, J. G.; Hathaway, D. H.; Whitaker, Ann F. (Technical Monitor)

    2001-01-01

    Previously, from analysis of SOHO/EIT coronal images in combination with Kitt Peak magnetograms (Falconer et al 1998, ApJ, 501, 386-396), we found that the quiet corona is the sum of two components: the e-scale corona and the coronal network. The large-scale corona consists of all coronal-temperature (T approx. 10(exp 6) K) structures larger than supergranules (>approx.30,000 km). The coronal network (1) consists of all coronal-temperature structures smaller than supergranules, (2) is rooted in and loosely traces the photospheric magnetic network, (3) has its brightest features seated on polarity dividing fines (neutral lines) in the network magnetic flux, and (4) produces only about 5% of the total coronal emission in quiet regions. The heating of the coronal network is apparently magnetic in origin. Here, from analysis of EIT coronal images of quiet regions in combination with magnetograms of the same quiet regions from SOHO/MDI and from Kitt Peak, we examine the other 95% of the quiet corona and its relation to the underlying magnetic network. We find: (1) Dividing the large-scale corona into its bright and dim halves divides the area into bright "continents" and dark "oceans" having spans of 2-4 supergranules. (2) These patterns are also present in the photospheric magnetograms: the network is stronger under the bright half and weaker under the dim half. (3) The radiation from the large-scale corona increases roughly as the cube root of the magnetic flux content of the underlying magnetic network. In contrast, Fisher et A (1998, ApJ, 508, 985-998) found that the coronal radiation from an active region increases roughly linearly with the magnetic flux content of the active region. We assume, as is widely held, that nearly all of the large-scale corona is magnetically rooted in the network. Our results, together with the result of Fisher et al (1999), suggest that either the coronal heating in quiet regions has a large non-magnetic component, or, if the heating

  13. The analysis of thermal network of district heating system from investor point of view

    NASA Astrophysics Data System (ADS)

    Takács, Ján; Rácz, Lukáš

    2016-06-01

    The hydraulics of a thermal network of a district heating system is a very important issue, to which not enough attention is often paid. In this paper the authors want to point out some of the important aspects of the design and operation of thermal networks in district heating systems. The design boundary conditions of a heat distribution network and the requirements on active pressure - circulation pump - influencing the operation costs of the centralized district heating system as a whole, are analyzed in detail. The heat generators and the heat exchange stations are designed according to the design heat loads after thermal insulation, and modern boiler units are installed in the heating plant.

  14. Possibility of using adsorption refrigeration unit in district heating network

    NASA Astrophysics Data System (ADS)

    Grzebielec, Andrzej; Rusowicz, Artur; Jaworski, Maciej; Laskowski, Rafał

    2015-09-01

    Adsorption refrigeration systems are able to work with heat sources of temperature starting with 50 °C. The aim of the article is to determine whether in terms of technical and economic issues adsorption refrigeration equipment can work as elements that produce cold using hot water from the district heating network. For this purpose, examined was the work of the adsorption air conditioning equipment cooperating with drycooler, and the opportunities offered by the district heating network in Warsaw during the summer. It turns out that the efficiency of the adsorption device from the economic perspective is not sufficient for production of cold even during the transitional period. The main problem is not the low temperature of the water supply, but the large difference between the coefficients of performance, COPs, of adsorption device and a traditional compressor air conditioning unit. When outside air temperature is 25 °C, the COP of the compressor type reaches a value of 4.49, whereas that of the adsorption device in the same conditions is 0.14. The ratio of the COPs is 32. At the same time ratio between the price of 1 kWh of electric power and 1 kWh of heat is only 2.85. Adsorption refrigeration equipment to be able to compete with compressor devices, should feature COPads efficiency to be greater than 1.52. At such a low driving temperature and even changing the drycooler into the evaporative cooler it is not currently possible to achieve.

  15. Energy recovery from waste incineration: Assessing the importance of district heating networks

    SciTech Connect

    Fruergaard, T.; Christensen, T.H.; Astrup, T.

    2010-07-15

    Municipal solid waste incineration contributes with 20% of the heat supplied to the more than 400 district heating networks in Denmark. In evaluation of the environmental consequences of this heat production, the typical approach has been to assume that other (fossil) fuels could be saved on a 1:1 basis (e.g. 1 GJ of waste heat delivered substitutes for 1 GJ of coal-based heat). This paper investigates consequences of waste-based heat substitution in two specific Danish district heating networks and the energy-associated interactions between the plants connected to these networks. Despite almost equal electricity and heat efficiencies at the waste incinerators connected to the two district heating networks, the energy and CO{sub 2} accounts showed significantly different results: waste incineration in one network caused a CO{sub 2} saving of 48 kg CO{sub 2}/GJ energy input while in the other network a load of 43 kg CO{sub 2}/GJ. This was caused mainly by differences in operation mode and fuel types of the other heat producing plants attached to the networks. The paper clearly indicates that simple evaluations of waste-to-energy efficiencies at the incinerator are insufficient for assessing the consequences of heat substitution in district heating network systems. The paper also shows that using national averages for heat substitution will not provide a correct answer: local conditions need to be addressed thoroughly otherwise we may fail to assess correctly the heat recovery from waste incineration.

  16. Energy recovery from waste incineration: assessing the importance of district heating networks.

    PubMed

    Fruergaard, T; Christensen, T H; Astrup, T

    2010-07-01

    Municipal solid waste incineration contributes with 20% of the heat supplied to the more than 400 district heating networks in Denmark. In evaluation of the environmental consequences of this heat production, the typical approach has been to assume that other (fossil) fuels could be saved on a 1:1 basis (e.g. 1GJ of waste heat delivered substitutes for 1GJ of coal-based heat). This paper investigates consequences of waste-based heat substitution in two specific Danish district heating networks and the energy-associated interactions between the plants connected to these networks. Despite almost equal electricity and heat efficiencies at the waste incinerators connected to the two district heating networks, the energy and CO(2) accounts showed significantly different results: waste incineration in one network caused a CO(2) saving of 48 kg CO(2)/GJ energy input while in the other network a load of 43 kg CO(2)/GJ. This was caused mainly by differences in operation mode and fuel types of the other heat producing plants attached to the networks. The paper clearly indicates that simple evaluations of waste-to-energy efficiencies at the incinerator are insufficient for assessing the consequences of heat substitution in district heating network systems. The paper also shows that using national averages for heat substitution will not provide a correct answer: local conditions need to be addressed thoroughly otherwise we may fail to assess correctly the heat recovery from waste incineration.

  17. Energy recovery from waste incineration: assessing the importance of district heating networks.

    PubMed

    Fruergaard, T; Christensen, T H; Astrup, T

    2010-07-01

    Municipal solid waste incineration contributes with 20% of the heat supplied to the more than 400 district heating networks in Denmark. In evaluation of the environmental consequences of this heat production, the typical approach has been to assume that other (fossil) fuels could be saved on a 1:1 basis (e.g. 1GJ of waste heat delivered substitutes for 1GJ of coal-based heat). This paper investigates consequences of waste-based heat substitution in two specific Danish district heating networks and the energy-associated interactions between the plants connected to these networks. Despite almost equal electricity and heat efficiencies at the waste incinerators connected to the two district heating networks, the energy and CO(2) accounts showed significantly different results: waste incineration in one network caused a CO(2) saving of 48 kg CO(2)/GJ energy input while in the other network a load of 43 kg CO(2)/GJ. This was caused mainly by differences in operation mode and fuel types of the other heat producing plants attached to the networks. The paper clearly indicates that simple evaluations of waste-to-energy efficiencies at the incinerator are insufficient for assessing the consequences of heat substitution in district heating network systems. The paper also shows that using national averages for heat substitution will not provide a correct answer: local conditions need to be addressed thoroughly otherwise we may fail to assess correctly the heat recovery from waste incineration. PMID:20385481

  18. Effective Augmentation of Complex Networks

    PubMed Central

    Wang, Jinjian; Yu, Xinghuo; Stone, Lewi

    2016-01-01

    Networks science plays an enormous role in many aspects of modern society from distributing electrical power across nations to spreading information and social networking amongst global populations. While modern networks constantly change in size, few studies have sought methods for the difficult task of optimising this growth. Here we study theoretical requirements for augmenting networks by adding source or sink nodes, without requiring additional driver-nodes to accommodate the change i.e., conserving structural controllability. Our “effective augmentation” algorithm takes advantage of clusters intrinsic to the network topology, and permits rapidly and efficient augmentation of a large number of nodes in one time-step. “Effective augmentation” is shown to work successfully on a wide range of model and real networks. The method has numerous applications (e.g. study of biological, social, power and technological networks) and potentially of significant practical and economic value. PMID:27165120

  19. Effective Augmentation of Complex Networks

    NASA Astrophysics Data System (ADS)

    Wang, Jinjian; Yu, Xinghuo; Stone, Lewi

    2016-05-01

    Networks science plays an enormous role in many aspects of modern society from distributing electrical power across nations to spreading information and social networking amongst global populations. While modern networks constantly change in size, few studies have sought methods for the difficult task of optimising this growth. Here we study theoretical requirements for augmenting networks by adding source or sink nodes, without requiring additional driver-nodes to accommodate the change i.e., conserving structural controllability. Our “effective augmentation” algorithm takes advantage of clusters intrinsic to the network topology, and permits rapidly and efficient augmentation of a large number of nodes in one time-step. “Effective augmentation” is shown to work successfully on a wide range of model and real networks. The method has numerous applications (e.g. study of biological, social, power and technological networks) and potentially of significant practical and economic value.

  20. Quantization Effects on Complex Networks

    PubMed Central

    Wang, Ying; Wang, Lin; Yang, Wen; Wang, Xiaofan

    2016-01-01

    Weights of edges in many complex networks we constructed are quantized values of the real weights. To what extent does the quantization affect the properties of a network? In this work, quantization effects on network properties are investigated based on the spectrum of the corresponding Laplacian. In contrast to the intuition that larger quantization level always implies a better approximation of the quantized network to the original one, we find a ubiquitous periodic jumping phenomenon with peak-value decreasing in a power-law relationship in all the real-world weighted networks that we investigated. We supply theoretical analysis on the critical quantization level and the power laws. PMID:27226049

  1. Quantization Effects on Complex Networks

    NASA Astrophysics Data System (ADS)

    Wang, Ying; Wang, Lin; Yang, Wen; Wang, Xiaofan

    2016-05-01

    Weights of edges in many complex networks we constructed are quantized values of the real weights. To what extent does the quantization affect the properties of a network? In this work, quantization effects on network properties are investigated based on the spectrum of the corresponding Laplacian. In contrast to the intuition that larger quantization level always implies a better approximation of the quantized network to the original one, we find a ubiquitous periodic jumping phenomenon with peak-value decreasing in a power-law relationship in all the real-world weighted networks that we investigated. We supply theoretical analysis on the critical quantization level and the power laws.

  2. Quantization Effects on Complex Networks.

    PubMed

    Wang, Ying; Wang, Lin; Yang, Wen; Wang, Xiaofan

    2016-01-01

    Weights of edges in many complex networks we constructed are quantized values of the real weights. To what extent does the quantization affect the properties of a network? In this work, quantization effects on network properties are investigated based on the spectrum of the corresponding Laplacian. In contrast to the intuition that larger quantization level always implies a better approximation of the quantized network to the original one, we find a ubiquitous periodic jumping phenomenon with peak-value decreasing in a power-law relationship in all the real-world weighted networks that we investigated. We supply theoretical analysis on the critical quantization level and the power laws. PMID:27226049

  3. Optimizing and controlling the operation of heat-exchanger networks

    SciTech Connect

    Aguilera, N.; Marchetti, J.L.

    1998-05-01

    A procedure was developed for on-line optimization and control systems of heat-exchanger networks, which features a two-level control structure, one for a constant configuration control system and the other for a supervisor on-line optimizer. The coordination between levels is achieved by adjusting the formulation of the optimization problem to meet requirements of the adopted control system. The general goal is always to work without losing stream temperature targets while keeping the highest energy integration. The operation constraints used for heat-exchanger and utility units emphasize the computation of heat-exchanger duties rather than intermediate stream temperatures. This simplifies the modeling task and provides clear links with the limits of the manipulated variables. The optimal condition is determined using LP or NLP, depending on the final problem formulation. Degrees of freedom for optimization and equation constraints for considering simple and multiple bypasses are rigorously discussed. An example used shows how the optimization problem can be adjusted to a specific network design, its expected operating space, and the control configuration. Dynamic simulations also show benefits and limitations of this procedure.

  4. Distributed Sensible Heat Flux Measurements for Wireless Sensor Networks

    NASA Astrophysics Data System (ADS)

    Huwald, H.; Brauchli, T.; Lehning, M.; Higgins, C. W.

    2015-12-01

    The sensible heat flux component of the surface energy balance is typically computed using eddy covariance or two point profile measurements while alternative approaches such as the flux variance method based on convective scaling has been much less explored and applied. Flux variance (FV) certainly has a few limitations and constraints but may be an interesting and competitive method in low-cost and power limited wireless sensor networks (WSN) with the advantage of providing spatio-temporal sensible heat flux over the domain of the network. In a first step, parameters such as sampling frequency, sensor response time, and averaging interval are investigated. Then we explore the applicability and the potential of the FV method for use in WSN in a field experiment. Low-cost sensor systems are tested and compared against reference instruments (3D sonic anemometers) to evaluate the performance and limitations of the sensors as well as the method with respect to the standard calculations. Comparison experiments were carried out at several sites to gauge the flux measurements over different surface types (gravel, grass, water) from the low-cost systems. This study should also serve as an example of spatially distributed sensible heat flux measurements.

  5. Heat-Passing Framework for Robust Interpretation of Data in Networks

    PubMed Central

    Fang, Yi; Sun, Mengtian; Ramani, Karthik

    2015-01-01

    Researchers are regularly interested in interpreting the multipartite structure of data entities according to their functional relationships. Data is often heterogeneous with intricately hidden inner structure. With limited prior knowledge, researchers are likely to confront the problem of transforming this data into knowledge. We develop a new framework, called heat-passing, which exploits intrinsic similarity relationships within noisy and incomplete raw data, and constructs a meaningful map of the data. The proposed framework is able to rank, cluster, and visualize the data all at once. The novelty of this framework is derived from an analogy between the process of data interpretation and that of heat transfer, in which all data points contribute simultaneously and globally to reveal intrinsic similarities between regions of data, meaningful coordinates for embedding the data, and exemplar data points that lie at optimal positions for heat transfer. We demonstrate the effectiveness of the heat-passing framework for robustly partitioning the complex networks, analyzing the globin family of proteins and determining conformational states of macromolecules in the presence of high levels of noise. The results indicate that the methodology is able to reveal functionally consistent relationships in a robust fashion with no reference to prior knowledge. The heat-passing framework is very general and has the potential for applications to a broad range of research fields, for example, biological networks, social networks and semantic analysis of documents. PMID:25668316

  6. Effects of heat stress on mammalian reproduction

    PubMed Central

    Hansen, Peter J.

    2009-01-01

    Heat stress can have large effects on most aspects of reproductive function in mammals. These include disruptions in spermatogenesis and oocyte development, oocyte maturation, early embryonic development, foetal and placental growth and lactation. These deleterious effects of heat stress are the result of either the hyperthermia associated with heat stress or the physiological adjustments made by the heat-stressed animal to regulate body temperature. Many effects of elevated temperature on gametes and the early embryo involve increased production of reactive oxygen species. Genetic adaptation to heat stress is possible both with respect to regulation of body temperature and cellular resistance to elevated temperature. PMID:19833646

  7. Exploring systems affected by the heat shock response in Plasmodium falciparum via protein association networks

    PubMed Central

    Lilburn, Timothy G.; Cai, Hong; Gu, Jianying; Zhou, Zhan; Wang, Yufeng

    2015-01-01

    The heat shock response is a general mechanism by which organisms deal with physical insults such as sudden changes in temperature, osmotic and oxidative stresses, and exposure to toxic substances. Plasmodium falciparum is exposed to drastic temperature changes as a part of its life cycle and maintains an extensive repertoire of heat shock response-related proteins. As these proteins serve to maintain the parasite in the face of anti-malarial drugs as well, better understanding of the heat shock-related systems in the malaria parasite will lead to therapeutic approaches that frustrate these systems, leading to more effective use of anti-malarials. Here we use protein association networks to broaden our understanding of the systems impacted by and/or implicated in the heat shock response. PMID:25539848

  8. Characteristics of Effective Leadership Networks

    ERIC Educational Resources Information Center

    Leithwood, Kenneth; Azah, Vera Ndifor

    2016-01-01

    Purpose: The purpose of this paper is to inquire about the characteristics of effective school leadership networks and the contribution of such networks to the development of individual leaders' professional capacities. Design/methodology/approach: The study used path-analytic techniques with survey data provided by 450 school and district leaders…

  9. Heat sink effects in VPPA welding

    NASA Technical Reports Server (NTRS)

    Steranka, Paul O., Jr.

    1990-01-01

    The development of a model for prediction of heat sink effects associated with the Variable Polarity Plasma Arc (VPPA) Welding Process is discussed. The long term goal of this modeling is to provide means for assessing potential heat sink effects and, eventually, to provide indications as to changes in the welding process that could be used to compensate for these effects and maintain the desired weld quality. In addition to the development of a theoretical model, a brief experimental investigation was conducted to demonstrate heat sink effects and to provide an indication of the accuracy of the model.

  10. An approach to estimate EEG power spectrum as an index of heat stress using backpropagation artificial neural network.

    PubMed

    Sinha, Rakesh Kumar

    2007-01-01

    A method has been presented for an effective application of backpropagation artificial neural network (ANN) in establishment of electro-encephalogram (EEG) power spectra as an index of stress in hot environment. The power spectrum data for slow wave sleep (SWS), rapid eye movement (REM) sleep and awake (AWA) states in three groups of rats (acute heat stress, chronic heat stress and the normal) were tested by an ANN, containing 60 nodes in input layer, weighted from power spectrum data from 0 to 30 Hz, 18 nodes in hidden layer and an output node. The target output values for this network were determined with another five-layered neural network (with the structure of 3-12-1-12-3). The input and output of this network was assigned with the three well-established heat stress indices (body temperature, body weight and plasma corticosterone). The most important feature for acute stress, chronic stress and normal conditions were extracted from the third layer single neuron and used for the target value for the three-layered neural network. The ANN was found effective in recognising the EEG power spectra with an average of 96.67% for acute heat stress, 97.17% for chronic heat stress and 98.5% for normal subjects.

  11. Effect of the Heat Pipe Adiabatic Region.

    PubMed

    Brahim, Taoufik; Jemni, Abdelmajid

    2014-04-01

    The main motivation of conducting this work is to present a rigorous analysis and investigation of the potential effect of the heat pipe adiabatic region on the flow and heat transfer performance of a heat pipe under varying evaporator and condenser conditions. A two-dimensional steady-state model for a cylindrical heat pipe coupling, for both regions, is presented, where the flow of the fluid in the porous structure is described by Darcy-Brinkman-Forchheimer model which accounts for the boundary and inertial effects. The model is solved numerically by using the finite volumes method, and a fortran code was developed to solve the system of equations obtained. The results show that a phase change can occur in the adiabatic region due to temperature gradient created in the porous structure as the heat input increases and the heat pipe boundary conditions change. A recirculation zone may be created at the condenser end section. The effect of the heat transfer rate on the vapor radial velocities and the performance of the heat pipe are discussed. PMID:24895467

  12. Thermally effective, electrically isolating heat intercept connections

    SciTech Connect

    Niemann, R.C.; Gonczy, J.D.; Nicol, T.H.

    1995-06-01

    Electrical and electronic equipment often require thermally effective beat intercept connections that provide electrical isolation. Such connections can be developed by clamping, with a thermal-interference fit, an electrically insulating cylindrical tube between a central disk and an outer ring. Heat flows radially through the disk-tube-ring assembly. Thermal effectiveness, i.e., {Delta}T for a given heat flux, and electrical isolation are controlled by tube geometry and material and by connection-assembly details. Connections of this type are being developed as cryogenic heat intercepts for electrical current leads that employ high-temperature superconductors. We discuss the design considerations and details of a beat intercept connection that transfers a 45-w thermal load at 60 K with a {Delta}T of {approx} 10 K while providing 7.5 kV electrical isolation. Prototype heat intercept connections have been evaluated for their thermal and electrical performance, and the results are presented.

  13. The effectiveness of a heated air curtain

    NASA Astrophysics Data System (ADS)

    Frank, Daria

    2014-11-01

    Air curtains are high-velocity plane turbulent jets which are installed in the doorway in order to reduce the heat and the mass exchange between two environments. The air curtain effectiveness E is defined as the fraction of the exchange flow prevented by the air curtain compared to the open-door situation. In the present study, we investigate the effects of an opposing buoyancy force on the air curtain effectiveness. Such an opposing buoyancy force arises for example if a downwards blowing air curtain is heated. We conducted small-scale experiments using water as the working fluid with density differences created by salt and sugar. The effectiveness of a downwards blowing air curtain was measured for situations in which the initial density of the air curtain was less than both the indoor and the outdoor fluid density, which corresponds to the case of a heated air curtain. We compare the effectiveness of the heated air curtain to the case of the neutrally buoyant air curtain. It is found that the effectiveness starts to decrease if the air curtain is heated beyond a critical temperature. Furthermore, we propose a theoretical model to describe the dynamics of the buoyant air curtain. Numerical results obtained from solving this model corroborate our experimental findings.

  14. The Small Heat Shock Protein Hsp27 Affects Assembly Dynamics and Structure of Keratin Intermediate Filament Networks

    PubMed Central

    Kayser, Jona; Haslbeck, Martin; Dempfle, Lisa; Krause, Maike; Grashoff, Carsten; Buchner, Johannes; Herrmann, Harald; Bausch, Andreas R.

    2013-01-01

    The mechanical properties of living cells are essential for many processes. They are defined by the cytoskeleton, a composite network of protein fibers. Thus, the precise control of its architecture is of paramount importance. Our knowledge about the molecular and physical mechanisms defining the network structure remains scarce, especially for the intermediate filament cytoskeleton. Here, we investigate the effect of small heat shock proteins on the keratin 8/18 intermediate filament cytoskeleton using a well-controlled model system of reconstituted keratin networks. We demonstrate that Hsp27 severely alters the structure of such networks by changing their assembly dynamics. Furthermore, the C-terminal tail domain of keratin 8 is shown to be essential for this effect. Combining results from fluorescence and electron microscopy with data from analytical ultracentrifugation reveals the crucial role of kinetic trapping in keratin network formation. PMID:24138853

  15. Simulated evolution of fractures and fracture networks subject to thermal cooling: A coupled discrete element and heat conduction model

    SciTech Connect

    Huang, Hai; Plummer, Mitchell; Podgorney, Robert

    2013-02-01

    Advancement of EGS requires improved prediction of fracture development and growth during reservoir stimulation and long-term operation. This, in turn, requires better understanding of the dynamics of the strongly coupled thermo-hydro-mechanical (THM) processes within fractured rocks. We have developed a physically based rock deformation and fracture propagation simulator by using a quasi-static discrete element model (DEM) to model mechanical rock deformation and fracture propagation induced by thermal stress and fluid pressure changes. We also developed a network model to simulate fluid flow and heat transport in both fractures and porous rock. In this paper, we describe results of simulations in which the DEM model and network flow & heat transport model are coupled together to provide realistic simulation of the changes of apertures and permeability of fractures and fracture networks induced by thermal cooling and fluid pressure changes within fractures. Various processes, such as Stokes flow in low velocity pores, convection-dominated heat transport in fractures, heat exchange between fluid-filled fractures and solid rock, heat conduction through low-permeability matrices and associated mechanical deformations are all incorporated into the coupled model. The effects of confining stresses, developing thermal stress and injection pressure on the permeability evolution of fracture and fracture networks are systematically investigated. Results are summarized in terms of implications for the development and evolution of fracture distribution during hydrofracturing and thermal stimulation for EGS.

  16. Characterizing the Urban Heat Island with a Dense Sensor Network

    NASA Astrophysics Data System (ADS)

    Snyder, P. K.; Twine, T. E.; Smoliak, B. V.; Mykleby, P.; Hertel, W. F.

    2014-12-01

    Urban heat islands (UHIs) occur when urban and suburban areas experience temperatures that are elevated relative to their rural surroundings because of differences in the fraction of gray and green infrastructure. Traditional methods of characterizing UHIs rely on the comparison of near-surface air temperature measurements between few sites in an urban area with those in a nearby rural area. This methodology assumes (1) that the UHI can be characterized by the difference in air temperature from a small number of points, and (2) that these few points represent the urban and rural signatures of the region. While this methodology makes it possible to compare the UHI of cities around the globe, it ignores the rich information that could be gained from measurements across the urban to rural transect. This transect could traverse elevations, water bodies, vegetation fraction, and other land surface properties. We deployed a network of ~200 temperature sensors across the Twin Cities Metropolitan Area (TCMA) beginning in July 2011 and continuing to the present. Our network covers a 5000-km2 area encompassing the cities of Minneapolis and Saint Paul as well as suburban and rural areas within the seven-county region. The TCMA includes ~3.4 million people, nearly 900 lakes, and two major interstate highways and a beltway system. We employed a cokriging method to interpolate sensor measurements onto a continuous grid using satellite-based impervious surface fraction data. Our results show consistent warm anomalies, when compared with a background rural temperature, over the two downtown cores and along major highways and dense suburban areas. Anomalies switch between positive and negative values (i.e., warmer or cooler than the rural, respectively) depending on season over large lakes. The warm season (May - October) average TCMA UHI (all urban areas - all rural areas) peaks at night at 1.5 °C, while the cold season (November - April) UHI is ~1 °C and is less variable over

  17. Effects of heat acclimation on time perception.

    PubMed

    Tamm, Maria; Jakobson, Ainika; Havik, Merle; Timpmann, Saima; Burk, Andres; Ööpik, Vahur; Allik, Jüri; Kreegipuu, Kairi

    2015-03-01

    Cognitive performance is impaired during prolonged exercise in hot environment compared to temperate conditions. These effects are related to both peripheral markers of heats stress and alterations in CNS functioning. Repeated-exposure to heat stress results in physiological adaptations, and therefore improvement in exercise capacity and cognitive functioning are observed. The objective of the current study was to clarify the factors contributing to time perception under heat stress and examine the effect of heat acclimation. 20 young healthy male subjects completed three exercise tests on a treadmill: H1 (at 60% VO(2)peak until exhaustion at 42°C), N (at 22°C; duration equal to H1) and H2 (walk until exhaustion at 42°C) following a 10-day heat acclimation program. Core temperature (T(C)) and heart rate (HR), ratings of perceived fatigue and exertion were obtained continuously during the exercise, and blood samples of hormones were taken before, during and after the exercise test for estimating the prolactin, growth hormone and cortisol response to acute exercise-heat stress. Interval production task was performed before, during and after the exercise test. Lower rate of rise in core temperature, heart rate, hormone response and subjective ratings indicated that the subjects had successfully acclimated. Before heat acclimation, significant distortions in produced intervals occurred after 60 minutes of exercise relative to pre-trial coefficients, indicating speeded temporal processing. However, this effect was absent after in acclimated subjects. Blood prolactin concentration predicted temporal performance in both conditions. Heat acclimation slows down the increase in physiological measures, and improvement in temporal processing is also evident. The results are explained within the internal clock model in terms of the pacemaker-accumulator functioning.

  18. Effects of heat acclimation on time perception.

    PubMed

    Tamm, Maria; Jakobson, Ainika; Havik, Merle; Timpmann, Saima; Burk, Andres; Ööpik, Vahur; Allik, Jüri; Kreegipuu, Kairi

    2015-03-01

    Cognitive performance is impaired during prolonged exercise in hot environment compared to temperate conditions. These effects are related to both peripheral markers of heats stress and alterations in CNS functioning. Repeated-exposure to heat stress results in physiological adaptations, and therefore improvement in exercise capacity and cognitive functioning are observed. The objective of the current study was to clarify the factors contributing to time perception under heat stress and examine the effect of heat acclimation. 20 young healthy male subjects completed three exercise tests on a treadmill: H1 (at 60% VO(2)peak until exhaustion at 42°C), N (at 22°C; duration equal to H1) and H2 (walk until exhaustion at 42°C) following a 10-day heat acclimation program. Core temperature (T(C)) and heart rate (HR), ratings of perceived fatigue and exertion were obtained continuously during the exercise, and blood samples of hormones were taken before, during and after the exercise test for estimating the prolactin, growth hormone and cortisol response to acute exercise-heat stress. Interval production task was performed before, during and after the exercise test. Lower rate of rise in core temperature, heart rate, hormone response and subjective ratings indicated that the subjects had successfully acclimated. Before heat acclimation, significant distortions in produced intervals occurred after 60 minutes of exercise relative to pre-trial coefficients, indicating speeded temporal processing. However, this effect was absent after in acclimated subjects. Blood prolactin concentration predicted temporal performance in both conditions. Heat acclimation slows down the increase in physiological measures, and improvement in temporal processing is also evident. The results are explained within the internal clock model in terms of the pacemaker-accumulator functioning. PMID:25451787

  19. Experimental investigation of heat transfer and effectiveness in corrugated plate heat exchangers having different chevron angles

    NASA Astrophysics Data System (ADS)

    Kılıç, Bayram; İpek, Osman

    2016-06-01

    In this study, heat transfer rate and effectiveness of corrugated plate heat exchangers having different chevron angles were investigated experimentally. Chevron angles of plate heat exchangers are β = 30° and β = 60°. For this purpose, experimentally heating system used plate heat exchanger was designed and constructed. Thermodynamic analysis of corrugated plate heat exchangers having different chevron angles were carried out. The heat transfer rate and effectiveness values are calculated. The experimental results are shown that heat transfer rate and effectiveness values for β = 60° is higher than that of the other. Obtained experimental results were graphically presented.

  20. Fast heat propagation in living tissue caused by branching artery network.

    PubMed

    Gafiychuk, V V; Lubashevsky, I A; Datsko, B Y

    2005-11-01

    We analyze the effect of blood flow through large arteries of peripheral circulation on heat transfer in living tissue. Blood flow in such arteries gives rise to fast heat propagation over large scales, which is described in terms of heat superdiffusion. The corresponding bioheat heat equation is derived. In particular, we show that under local strong heating of a small tissue domain the temperature distribution inside the surrounding tissue is affected substantially by heat superdiffusion.

  1. Chemical heat pump cost effectiveness evaluation

    NASA Astrophysics Data System (ADS)

    Standley, W. R.

    1982-02-01

    The cost-effectiveness and energy-effectiveness of existing chemical heat pump (CHP) concepts is compared with a baseline of conventional energy technologies and a group of near-term emerging energy technologies with which CHPs are expected to compete. The analysis is structured to evaluate these systems functioning as the primary space conditioning unit of both a 'standard' single-family detached home and a 'representative' commercial building. Each HVAC system and application is analyzed in each of two locations in the United States, the southwest (Albuquerque, NM) and the northeast (Boston, MA). In addition, the CHPs are evaluated in a 'representative' industrial waste heat upgrading application, and compared to potentially-competitive technologies for industrial 'heat pumping'.

  2. D0 HVAC System Heat Pump Controller Programming, Networking, and Operating Information

    SciTech Connect

    Anderson, B.; /Fermilab

    1999-12-02

    The purpose of this engineering note is to provide the necessary information to setup, program, and network the Electronic Systems USA Heat Pump Controller with the LON network card and Intellution Fix32 to operate properly within the HVAC system at D-Zero. The heat pump controllers are used for local temperature control of the office environments on the fifth and six floors of D-Zero. Heat pump units 1-6 are located in the ceiling of the sixth floor. Heat pump units 7-12 are found in the fifth floor ceiling. Heat pump unit 13 is in the Southeast corner of the fifth floor. Prior to installation the heat pump controller must be properly prepared to operate correctly in the HVAC system. Each heat pump unit must contain firmware (software) version 1.31 to operate properly on the network. Controllers with version 1.30 will not be able to communicate over the LON network. The manufacturer can only update the firmware version. Before installation a series of heat pump setpoints must be manually set using the Intelligent Stat. Connect the Intelligent Stat via the serial cable or wired connection.

  3. The effective latent heat of aqueous nanofluids

    NASA Astrophysics Data System (ADS)

    Lee, Soochan; Taylor, Robert A.; Dai, Lenore; Prasher, Ravi; Phelan, Patrick E.

    2015-06-01

    Nanoparticle suspensions, popularly termed ‘nanofluids’, have been extensively investigated for their thermal and radiative properties (Eastman et al 1996 Mater. Res. Soc. Proc. 457; Keblinski et al 2005 Mater. Today 8 36-44 Barber et al 2011 Nanoscale Res. Lett. 6 1-13 Thomas and Sobhan 2011 Nanoscale Res. Lett. 6 1-21 Taylor et al 2011 Nanoscale Res. Lett. 6 1-11 Fang et al 2013 Nano Lett. 13 1736-42 Otanicar et al 2010 J. Renew. Sustainable Energy 2 03310201-13 Prasher et al 2006 ASME J. Heat Transfer 128 588-95 Shin and Banerjee 2011 ASME J. Heat Transfer 133 1-4 Taylor and Phelan 2009 Int. J. Heat Mass Transfer 52 5339-48 Ameen et al 2010 Int. J. Thermophys. 31 1131-44 Lee et al 2014 Appl. Phys. Lett. 104 1-4). Such work has generated great controversy, although it is (arguably) generally accepted today that the presence of nanoparticles rarely leads to useful enhancements in either thermal conductivity or convective heat transfer. On the other hand, there are still examples of unanticipated enhancements to some properties, such as the specific heat of molten salt-based nanofluids reported by Shin and Banerjee (2011 ASME J. Heat Transfer 133 1-4) and the critical heat flux mentioned by Taylor and Phelan (2009 Int. J. Heat Mass Transfer 52 5339-48). Another largely overlooked example is the reported effect of nanoparticles on the effective latent heat of vaporization (hfg) of aqueous nanofluids, as reported by Ameen et al (2010 Int. J. Thermophys. 31 1131-44). Through molecular dynamics (MD) modeling supplemented with limited experimental data they found that hfg increases with increasing nanoparticle concentration, for Pt nanoparticles (MD) and Al2O3 nanoparticles (experiments). Here, we extend those exploratory experiments in an effort to determine if hfg of aqueous nanofluids can be manipulated, i.e., increased or decreased by the addition of graphite or silver nanoparticles. Our results to date indicate that, yes, hfg can be substantially impacted, by

  4. A new estimator of heat periods for decadal climate predictions - a complex network approach

    NASA Astrophysics Data System (ADS)

    Weimer, Michael; Mieruch, Sebastian; Schädler, Gerd; Kottmeier, Christoph

    2016-08-01

    Regional decadal predictions have emerged in the past few years as a research field with high application potential, especially for extremes like heat and drought periods. However, up to now the prediction skill of decadal hindcasts, as evaluated with standard methods, is moderate and for extreme values even rarely investigated. In this study, we use hindcast data from a regional climate model (CCLM) for eight regions in Europe and quantify the skill of the model alternatively by constructing time-evolving climate networks and use the network correlation threshold (link strength) as a predictor for heat periods. We show that the skill of the network measure to estimate the low-frequency dynamics of heat periods is superior for decadal predictions with respect to the typical approach of using a fixed temperature threshold for estimating the number of heat periods in Europe.

  5. Estimating losses in heat networks coated with modern liquid crystal thermal insulation

    NASA Astrophysics Data System (ADS)

    Ilyin, R. A.

    2015-07-01

    One of the present issues during heat network operation in Russia is the losses of thermal energy at its transfer to consumers. According to statements of experts, losses in heat networks reach 35-50%. In this work, some properties of thermo-insulating materials currently in use are described. The innovative TLM Ceramic liquid-crystal thermal insulation is presented by its positive technical and economical characteristics, as well as field-performance data, and the doubts of experts about its declared properties. Location measurement data are presented for Astrakhan Severnaya heat and power plant hot-water system section covered with the 2-mm-thick liquid-crystal thermal insulation layer. Specific heat losses from the hot-water system surface have been determined and the arguments for inexpediency of applying TLM Ceramic liquid-crystal thermal insulation in heat-and-power engineering are discussed.

  6. Heat Entrapment Effects Within Liquid Acquisition Devices

    NASA Technical Reports Server (NTRS)

    Duval, W. M. B.; Chato, D. J.; Doherty, M. P.

    2010-01-01

    We introduce a model problem to address heat entrapment effects or the local accumulation of thermal energy within liquid acquisition devices. We show that the parametric space consists of six parameters, namely the Rayleigh and Prandtl numbers, the aspect ratio, and heat flux ratios for the bottom, side, and top boundaries of the enclosure. For the range of Ra considered 1 to 10(sup 9), beyond Ra on the order of 10(sup 5), convective instability is the dominant mode of convection in comparison to natural convection. The flow field transitions to asymmetric modes at Ra on the order of 10(sup 7). Direct numerical simulation of a large geometric length scale prototype for Ra on the order of 10(sup 9) shows that the flow field evolves from small wavelength instability which gives rise to nonlinear growth of thermals, propagation of the instability occurs via growth of secondary and tertiary modes, and a travelling wave mode occurs prior to asymmetry. The effect of a large aspect ratio is to increase the number of modes in the vertical direction. Due to the slow diffusion of heat in the prototype, asymptotic states are not readily attained, we show that dynamical similarity can be used for a model which allows the attainment of asymptotic states and that transition to a chaotic state occurs for Ra on the order of 10(sup 9) via a broadband power spectrum. These dynamical events show that for the baseline condition in which heat is absorbed from background laboratory environment, higher heat flux is absorbed at the top and bottom boundaries of the enclosure than a nominal value of 34.9 ergs per square centimeter -second.

  7. Predicting the heating value of MSW with a feed forward neural network

    SciTech Connect

    Dong Changqing; Jin Baosheng; Li Daji

    2003-07-01

    The influence of the heating value of municipal solid waste (MSW) is very important on the combustion efficiency of MSW incinerators. The heating value of MSW is determined by the elementary chemical composition of its various components. Commonly, calorimetric measurement and empirical methods are available for this determination. In this analysis, the relationship between the physical composition and the low heating value (LHV) was studied. A feed forward neural network (FFNN) can be very helpful in predicting the heating value of MSW from its physical composition. The results of this analysis show that the prediction of LHV of MSW with FFNN is much better than conventional models.

  8. Brain mediators of the effects of noxious heat on pain.

    PubMed

    Atlas, Lauren Y; Lindquist, Martin A; Bolger, Niall; Wager, Tor D

    2014-08-01

    Recent human neuroimaging studies have investigated the neural correlates of either noxious stimulus intensity or reported pain. Although useful, analyzing brain relationships with stimulus intensity and behavior separately does not address how sensation and pain are linked in the central nervous system. In this study, we used multi-level mediation analysis to identify brain mediators of pain--regions in which trial-by-trial responses to heat explained variability in the relationship between noxious stimulus intensity (across 4 levels) and pain. This approach has the potential to identify multiple circuits with complementary roles in pain genesis. Brain mediators of noxious heat effects on pain included targets of ascending nociceptive pathways (anterior cingulate, insula, SII, and medial thalamus) and also prefrontal and subcortical regions not associated with nociceptive pathways per se. Cluster analysis revealed that mediators were grouped into several distinct functional networks, including the following: somatosensory, paralimbic, and striatal-cerebellar networks that increased with stimulus intensity; and 2 networks co-localized with "default mode" regions in which stimulus intensity-related decreases mediated increased pain. We also identified "thermosensory" regions that responded to increasing noxious heat but did not predict pain reports. Finally, several regions did not respond to noxious input, but their activity predicted pain; these included ventromedial prefrontal cortex, dorsolateral prefrontal cortex, cerebellar regions, and supplementary motor cortices. These regions likely underlie both nociceptive and non-nociceptive processes that contribute to pain, such as attention and decision-making processes. Overall, these results elucidate how multiple distinct brain systems jointly contribute to the central generation of pain.

  9. Effects of one-sided heat input and removal on axially grooved heat pipe performance

    NASA Technical Reports Server (NTRS)

    Kamotani, Y.

    1977-01-01

    The performance of an axially grooved heat pipe with one-sided heat input and removal was investigated analytically. Under zero-g condition the maximum heat transport of the pipe may decrease as much as 30% depending on the liquid slug behavior in the condenser section. In one-g environment the performance depends mainly on the fluid charge. The maximum heat transport, if over-charged, is almost equal to the value for uniform heating and cooling due to puddling effect. However, for some heater-cooler combinations the temperature drop across the heat pipe becomes very large. Computed results for tilted heat pipes compare favorably with available experimental data.

  10. Prospects of engineering thermotolerance in crops through modulation of heat stress transcription factor and heat shock protein networks.

    PubMed

    Fragkostefanakis, Sotirios; Röth, Sascha; Schleiff, Enrico; Scharf, Klaus-Dieter

    2015-09-01

    Cell survival under high temperature conditions involves the activation of heat stress response (HSR), which in principle is highly conserved among different organisms, but shows remarkable complexity and unique features in plant systems. The transcriptional reprogramming at higher temperatures is controlled by the activity of the heat stress transcription factors (Hsfs). Hsfs allow the transcriptional activation of HSR genes, among which heat shock proteins (Hsps) are best characterized. Hsps belong to multigene families encoding for molecular chaperones involved in various processes including maintenance of protein homeostasis as a requisite for optimal development and survival under stress conditions. Hsfs form complex networks to activate downstream responses, but are concomitantly subjected to cell-type-dependent feedback regulation through factor-specific physical and functional interactions with chaperones belonging to Hsp90, Hsp70 and small Hsp families. There is increasing evidence that the originally assumed specialized function of Hsf/chaperone networks in the HSR turns out to be a complex central stress response system that is involved in the regulation of a broad variety of other stress responses and may also have substantial impact on various developmental processes. Understanding in detail the function of such regulatory networks is prerequisite for sustained improvement of thermotolerance in important agricultural crops.

  11. Triple-shape effect in polymer-based composites by cleverly matching geometry of active component with heating method.

    PubMed

    Razzaq, M Y; Behl, M; Kratz, K; Lendlein, A

    2013-10-11

    A triple-shape effect is created for a segmented device consisting of an active component encapsulated in a highly flexible polymer network. Segments with the same composition but different interface areas can be recovered independently either at specific field strengths (Hsw ) during inductive heating, at a specific time during environmentally heating, or at different airflow during inductive heating at constant H. Herein the type of heating method regulates the sequence order.

  12. Network effects of animal conflicts

    NASA Astrophysics Data System (ADS)

    Yu, You-Yang; Ni, Yang-Chun

    2008-11-01

    We simulated animal conflicts on different networks, where five strategies that the animals may take are considered. The result of the evolution of the five strategies on networks shows that whether one strategy dominates or two strategies coexist on the network is determined by the structure of the network. But no matter what structure the network is, the total-war strategy is constrained and never becomes a final winning strategy when it contests with the other four limited-war strategies. This may be the reason that the animals choose the limited-war strategies to fight against other animals of the same species.

  13. Neurophysiological effects of exercise in the heat.

    PubMed

    Roelands, B; De Pauw, K; Meeusen, R

    2015-06-01

    Fatigue during prolonged exercise is a multifactorial phenomenon. The complex interplay between factors originating from both the periphery and the brain will determine the onset of fatigue. In recent years, electrophysiological and imaging tools have been fine-tuned, allowing for an improved understanding of what happens in the brain. In the first part of the review, we present literature that studied the changes in electrocortical activity during and after exercise in normal and high ambient temperature. In general, exercise in a thermo-neutral environment or at light to moderate intensity increases the activity in the β frequency range, while exercising at high intensity or in the heat reduces β activity. In the second part, we review literature that manipulated brain neurotransmission, through either pharmacological or nutritional means, during exercise in the heat. The dominant outcomes were that manipulations changing brain dopamine concentration have the potential to delay fatigue, while the manipulation of serotonin had no effect and noradrenaline reuptake inhibition was detrimental for performance in the heat. Research on the effects of neurotransmitter manipulations on brain activity during or after exercise is scarce. The combination of brain imaging techniques with electrophysiological measures presents one of the major future challenges in exercise physiology/neurophysiology. PMID:25943657

  14. Neurophysiological effects of exercise in the heat.

    PubMed

    Roelands, B; De Pauw, K; Meeusen, R

    2015-06-01

    Fatigue during prolonged exercise is a multifactorial phenomenon. The complex interplay between factors originating from both the periphery and the brain will determine the onset of fatigue. In recent years, electrophysiological and imaging tools have been fine-tuned, allowing for an improved understanding of what happens in the brain. In the first part of the review, we present literature that studied the changes in electrocortical activity during and after exercise in normal and high ambient temperature. In general, exercise in a thermo-neutral environment or at light to moderate intensity increases the activity in the β frequency range, while exercising at high intensity or in the heat reduces β activity. In the second part, we review literature that manipulated brain neurotransmission, through either pharmacological or nutritional means, during exercise in the heat. The dominant outcomes were that manipulations changing brain dopamine concentration have the potential to delay fatigue, while the manipulation of serotonin had no effect and noradrenaline reuptake inhibition was detrimental for performance in the heat. Research on the effects of neurotransmitter manipulations on brain activity during or after exercise is scarce. The combination of brain imaging techniques with electrophysiological measures presents one of the major future challenges in exercise physiology/neurophysiology.

  15. Effects of anisotropic heat conduction on solidification

    NASA Technical Reports Server (NTRS)

    Weaver, J. A.; Viskanta, R.

    1989-01-01

    Two-dimensional solidification influenced by anisotropic heat conduction has been considered. The interfacial energy balance was derived to account for the heat transfer in one direction (x or y) depending on the temperature gradient in both the x and y directions. A parametric study was made to determine the effects of the Stefan number, aspect ratio, initial superheat, and thermal conductivity ratios on the solidification rate. Because of the imposed boundary conditions, the interface became skewed and sometimes was not a straight line between the interface position at the upper and lower adiabatic walls (spatially nonlinear along the height). This skewness depends on the thermal conductivity ratio k(yy)/k(yx). The nonlinearity of the interface is influenced by the solidification rate, aspect ratio, and k(yy/k(yx).

  16. Effects of anisotropic heat conduction on solidification

    SciTech Connect

    Weaver, J.A.; Viskanta, R.

    1989-01-01

    Two-dimensional solidfication influenced by anisotropic heat conductions has been considered. The interfacial energy balance was derived to account for the heat transfer in one direction (x or y) depending on the temperature gradient in both the x and y directions. A parametric study was made to determine the effect of Stefan number, aspect ratio, initial superheat, and thermal conductivity ratios on the solidification rate. Because of the imposed boundary conditions, the interface became skewed and sometimes was not a straight line between the interface position at the upper and lower adiabatic walls (spatially nonlinear along the height). This skewness depends on the thermal conductivity ratio k/sub yy//k/sub yx/. The nonlinearity of the interface is influenced by the solidificaton rate, aspect ratio, and k/sub yy//k/sub yx/.

  17. Electric heating effects in nematic liquid crystals

    NASA Astrophysics Data System (ADS)

    Yin, Y.; Shiyanovskii, S. V.; Lavrentovich, O. D.

    2006-07-01

    Electric heating effects in the nematic liquid crystal change the liquid crystal physical properties and dynamics. We propose a model to quantitatively describe the heating effects caused by dielectric dispersion and ionic conductivity in the nematic liquid crystals upon the application of an ac electric field. The temperature increase of the liquid crystal cell is related to the properties of the liquid crystal such as the imaginary part of the dielectric permittivity, thermal properties of the bounding plates, and the surrounding medium as well as frequency and amplitude of the electric field. To study the temperature dynamics experimentally, we use a small thermocouple inserted directly into the nematic bulk; we assure that the thermocouple does not alter the thermal behavior of the system by comparing the results to those obtained by a noncontact birefringent probing technique recently proposed by Wen and Wu [Appl. Phys. Lett. 86, 231104 (2005)]. We determine how the temperature dynamics and the stationary value of the temperature increase depend on the parameters of the materials and the applied field. We used different surrounding media, from extremely good heat conductors such as aluminum cooling device to extremely poor conductor, Styrofoam; these two provide two limiting cases as compared to typical conditions of nematic cell exploitation in a laboratory or in commercial devices. The experiments confirm the theoretical predictions, namely, that the temperature rise is controlled not only by the heat transfer coefficient of the surrounding medium (as in the previous model) but also by the thickness and the thermal conductivity coefficient of the bounding plates enclosing the nematic layer. The temperature increase strongly depends on the director orientation and can change nonmonotonously with the frequency of the applied field.

  18. Network Effects on Scientific Collaborations

    PubMed Central

    Uddin, Shahadat; Hossain, Liaquat; Rasmussen, Kim

    2013-01-01

    Background The analysis of co-authorship network aims at exploring the impact of network structure on the outcome of scientific collaborations and research publications. However, little is known about what network properties are associated with authors who have increased number of joint publications and are being cited highly. Methodology/Principal Findings Measures of social network analysis, for example network centrality and tie strength, have been utilized extensively in current co-authorship literature to explore different behavioural patterns of co-authorship networks. Using three SNA measures (i.e., degree centrality, closeness centrality and betweenness centrality), we explore scientific collaboration networks to understand factors influencing performance (i.e., citation count) and formation (tie strength between authors) of such networks. A citation count is the number of times an article is cited by other articles. We use co-authorship dataset of the research field of ‘steel structure’ for the year 2005 to 2009. To measure the strength of scientific collaboration between two authors, we consider the number of articles co-authored by them. In this study, we examine how citation count of a scientific publication is influenced by different centrality measures of its co-author(s) in a co-authorship network. We further analyze the impact of the network positions of authors on the strength of their scientific collaborations. We use both correlation and regression methods for data analysis leading to statistical validation. We identify that citation count of a research article is positively correlated with the degree centrality and betweenness centrality values of its co-author(s). Also, we reveal that degree centrality and betweenness centrality values of authors in a co-authorship network are positively correlated with the strength of their scientific collaborations. Conclusions/Significance Authors’ network positions in co-authorship networks influence

  19. Network effects, cascades and CCP interoperability

    NASA Astrophysics Data System (ADS)

    Feng, Xiaobing; Hu, Haibo; Pritsker, Matthew

    2014-03-01

    To control counterparty risk, financial regulations such as the Dodd Frank Act are increasingly requiring standardized derivatives trades to be cleared by central counterparties (CCPs). It is anticipated that in the near-term future, CCPs across the world will be linked through interoperability agreements that facilitate risk-sharing but also serve as a conduit for transmitting shocks. This paper theoretically studies a network with CCPs that are linked through interoperability arrangements, and studies the properties of the network that contribute to cascading failures. The magnitude of the cascading is theoretically related to the strength of network linkages, the size of the network, the logistic mapping coefficient, a stochastic effect and CCP's defense lines. Simulations indicate that larger network effects increase systemic risk from cascading failures. The size of the network N raises the threshold value of shock sizes that are required to generate cascades. Hence, the larger the network, the more robust it will be.

  20. Effects of simulated heat waves on ApoE-/- mice.

    PubMed

    Wang, Chunling; Zhang, Shuyu; Tian, Ying; Wang, Baojian; Shen, Shuanghe

    2014-02-01

    The effects of simulated heat waves on body weight, body temperature, and biomarkers of cardiac function in ApoE-/- mice were investigated. Heat waves were simulated in a meteorological environment simulation chamber according to data from a heat wave that occurred in July 2001 in Nanjing, China. Eighteen ApoE-/- mice were divided into control group, heat wave group, and heat wave BH4 group. Mice in the heat wave and BH4 groups were exposed to simulated heat waves in the simulation chamber. Mice in BH4 group were treated with gastric lavage with BH4 2 h prior to heat wave exposure. Results showed that the heat waves did not significantly affect body weight or ET-1 levels. However, mice in the heat wave group had significantly higher rectal temperature and NO level and lower SOD activity compared with mice in the control group (p < 0.01), indicating that heat wave had negative effects on cardiac function in ApoE-/- mice. Gastric lavage with BH4 prior to heat wave exposure significantly reduced heat wave-induced increases in rectal temperature and decreases in SOD activity. Additionally, pretreatment with BH4 further increased NO level in plasma. Collectively, these beneficial effects demonstrate that BH4 may potentially mitigate the risk of coronary heart disease in mice under heat wave exposure. These results may be useful when studying the effects of heat waves on humans. PMID:24477215

  1. Effects of simulated heat waves on ApoE-/- mice.

    PubMed

    Wang, Chunling; Zhang, Shuyu; Tian, Ying; Wang, Baojian; Shen, Shuanghe

    2014-02-01

    The effects of simulated heat waves on body weight, body temperature, and biomarkers of cardiac function in ApoE-/- mice were investigated. Heat waves were simulated in a meteorological environment simulation chamber according to data from a heat wave that occurred in July 2001 in Nanjing, China. Eighteen ApoE-/- mice were divided into control group, heat wave group, and heat wave BH4 group. Mice in the heat wave and BH4 groups were exposed to simulated heat waves in the simulation chamber. Mice in BH4 group were treated with gastric lavage with BH4 2 h prior to heat wave exposure. Results showed that the heat waves did not significantly affect body weight or ET-1 levels. However, mice in the heat wave group had significantly higher rectal temperature and NO level and lower SOD activity compared with mice in the control group (p < 0.01), indicating that heat wave had negative effects on cardiac function in ApoE-/- mice. Gastric lavage with BH4 prior to heat wave exposure significantly reduced heat wave-induced increases in rectal temperature and decreases in SOD activity. Additionally, pretreatment with BH4 further increased NO level in plasma. Collectively, these beneficial effects demonstrate that BH4 may potentially mitigate the risk of coronary heart disease in mice under heat wave exposure. These results may be useful when studying the effects of heat waves on humans.

  2. Molecular characterization of two small heat shock protein genes in rice: their expression patterns, localizations, networks, and heterogeneous overexpressions.

    PubMed

    Ham, Deok-Jae; Moon, Jun-Chul; Hwang, Sun-Goo; Jang, Cheol Seong

    2013-09-28

    Heat stress is an example of a severe abiotic stress that plants can suffer in the field, causing a significant detrimental effect on their growth and productivity. Understanding the mechanism of plant response to heat stress is important for improving the productivity of crop plants under global warming. We used a microarray dataset that is deposited in the public database to evaluate plant responses to heat stress, and we selected the top 10 genes that are highly expressed under heat stress in rice. Two genes, OsSHSP1 (Os03g16030) and OsSHSP2 (Os01g04380), were selected for further study. These genes were highly induced in response to salt and drought but not in response to cold. In addition, OsSHSP1 and OsSHSP2 gene transcripts were induced under abscisic acid and salicylic acid but not under jasmonic acid and ethylene. Subcellular localization of proteins of 35S::OsSHSP1 were associated with the cytosol, whereas those of and 35S::OsSHSP2 were associated with the cytosol and nucleus. Heterogeneous overexpression of both genes exhibited higher germination rates than those of wild-type plants under the salt treatment, but not under heat or drought stress, supporting a hypothesis regarding functional specialization of members of small heat-shock protein family over evolutionary time. The network of both genes harboring nine sHSPs as well as at least 13 other chaperone genes might support the idea of a role for sHSPs in the chaperone network. Our findings might provide clues to shed light on the molecular functions of OsSHSP1 and OsSHSP2 in response to abiotic stresses, especially heat stress.

  3. Generation of whistler-wave heated discharges with planar resonant RF networks.

    PubMed

    Guittienne, Ph; Howling, A A; Hollenstein, Ch

    2013-09-20

    Magnetized plasma discharges generated by a planar resonant rf network are investigated. A regime transition is observed above a magnetic field threshold, associated with rf waves propagating in the plasma and which present the characteristics of whistler waves. These wave heated regimes can be considered as analogous to conventional helicon discharges, but in planar geometry.

  4. Effect of acute heat stress on plant nutrient metabolism proteins

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Abrupt heating decreased the levels (per unit total root protein) of all but one of the nutrient metabolism proteins examined, and for most of the proteins, effects were greater for severe vs. moderate heat stress. For many of the nutrient metabolism proteins, initial effects of heat (1 d) were r...

  5. An Inquiry into the Effect of Heating on Ascorbic Acid

    ERIC Educational Resources Information Center

    Yip, Din Yan

    2009-01-01

    Investigations that study the effect of heating on ascorbic acid are commonly performed in schools, but the conclusions obtained are quite variable and controversial. Some results indicate that heating may destroy vitamin C, but others suggest that heating may have no effect. This article reports an attempt to resolve this confusion through a…

  6. Effects of heat recovery for district heating on waste incineration health impact: a simulation study in Northern Italy.

    PubMed

    Cordioli, Michele; Vincenzi, Simone; De Leo, Giulio A

    2013-02-01

    The construction of waste incinerators in populated areas always causes substantial public concern. Since the heat from waste combustion can be recovered to power district heating networks and allows for the switch-off of domestic boilers in urbanized areas, predictive models for health assessment should also take into account the potential benefits of abating an important source of diffuse emission. In this work, we simulated the dispersion of atmospheric pollutants from a waste incinerator under construction in Parma (Italy) into different environmental compartments and estimated the potential health effect of both criteria- (PM(10)) and micro-pollutants (PCDD/F, PAH, Cd, Hg). We analyzed two emission scenarios, one considering only the new incinerator, and the other accounting for the potential decrease in pollutant concentrations due to the activation of a district heating network. We estimated the effect of uncertainty in parameter estimation on health risk through Monte Carlo simulations. In addition, we analyzed the robustness of health risk to alternative assumptions on: a) the geographical origins of the potentially contaminated food, and b) the dietary habits of the exposed population. Our analysis showed that under the specific set of assumptions and emission scenarios explored in the present work: (i) the proposed waste incinerator plant appears to cause negligible harm to the resident population; (ii) despite the net increase in PM(10) mass balance, ground-level concentration of fine particulate matter may be curbed by the activation of an extensive district heating system powered through waste combustion heat recovery and the concurrent switch-off of domestic/industrial heating boilers. In addition, our study showed that the health risk caused by waste incineration emissions is sensitive to assumptions about the typical diet of the resident population, and the geographical origins of food production.

  7. Effect of prior heat shock on heat resistance of Listeria monocytogenes in meat.

    PubMed Central

    Farber, J M; Brown, B E

    1990-01-01

    The effect of prior heat shock on the thermal resistance of Listeria monocytogenes in meat was investigated. A sausage mix inoculated with approximately 10(7) L. monocytogenes per g was initially subjected to a heat shock temperature of 48 degrees C before being heated at a final test temperature of 62 or 64 degrees C. Although cells heat shocked at 48 degrees C for 30 or 60 min did not show a significant increase in thermotolerance as compared with control cells (non-heat shocked), bacteria heat shocked for 120 min did, showing an average 2.4-fold increase in the D64 degrees C value. Heat-shocked cells shifted to 4 degrees C appeared to maintain their thermotolerance for at least 24 h after heat shock. PMID:2116757

  8. The application of complex network time series analysis in turbulent heated jets

    SciTech Connect

    Charakopoulos, A. K.; Karakasidis, T. E. Liakopoulos, A.; Papanicolaou, P. N.

    2014-06-15

    In the present study, we applied the methodology of the complex network-based time series analysis to experimental temperature time series from a vertical turbulent heated jet. More specifically, we approach the hydrodynamic problem of discriminating time series corresponding to various regions relative to the jet axis, i.e., time series corresponding to regions that are close to the jet axis from time series originating at regions with a different dynamical regime based on the constructed network properties. Applying the transformation phase space method (k nearest neighbors) and also the visibility algorithm, we transformed time series into networks and evaluated the topological properties of the networks such as degree distribution, average path length, diameter, modularity, and clustering coefficient. The results show that the complex network approach allows distinguishing, identifying, and exploring in detail various dynamical regions of the jet flow, and associate it to the corresponding physical behavior. In addition, in order to reject the hypothesis that the studied networks originate from a stochastic process, we generated random network and we compared their statistical properties with that originating from the experimental data. As far as the efficiency of the two methods for network construction is concerned, we conclude that both methodologies lead to network properties that present almost the same qualitative behavior and allow us to reveal the underlying system dynamics.

  9. Modeling terahertz heating effects on water.

    PubMed

    Kristensen, Torben T L; Withayachumnankul, Withawat; Jepsen, Peter U; Abbott, Derek

    2010-03-01

    We apply Kirchhoff's heat equation to model the influence of a CW terahertz beam on a sample of water, which is assumed to be static. We develop a generalized model, which easily can be applied to other liquids and solids by changing the material constants. If the terahertz light source is focused down to a spot with a diameter of 0.5 mm, we find that the steady-state temperature increase per milliwatt of transmitted power is 1.8?C/mW. A quantum cascade laser can produce a CW beam in the order of several milliwatts and this motivates the need to estimate the effect of beam power on the sample temperature. For THz time domain systems, we indicate how to use our model as a worst-case approximation based on the beam average power. It turns out that THz pulses created from photoconductive antennas give a negligible increase in temperature. As biotissue contains a high water content, this leads to a discussion of worst-case predictions for THz heating of the human body in order to motivate future detailed study. An open source Matlab implementation of our model is freely available for use at www.eleceng.adelaide.edu.au/thz. PMID:20389486

  10. Performance prediction between horizontal and vertical source heat pump systems for greenhouse heating with the use of artificial neural networks

    NASA Astrophysics Data System (ADS)

    Benli, Hüseyin

    2016-08-01

    This paper presents the suitability of artificial neural networks (ANNs) to predict the performance and comparison between a horizontal and a vertical ground source heat pump system. Performance forecasting is the precondition for the optimal control and energy saving operation of heat pump systems. In this study, performance parameters such as air temperature entering condenser fan-coil unit, air temperature leaving condenser fan-coil unit, and ground temperatures (2 and 60 m) obtained experimental studies are input data; coefficient of performance of system (COPsys) is in output layer. The back propagation learning algorithm with three different variants such as Levenberg-Marguardt, Pola-Ribiere conjugate gradient, and scaled conjugate gradient, and also tangent sigmoid transfer function were used in the network so that the best approach can be found. The results showed that LM with three neurons in the hidden layer is the most suitable algorithm with maximum correlation coefficients R2 of 0.999, minimum root mean square RMS value and low coefficient variance COV. The reported results confirmed that the use of ANN for performance prediction of COPsys,H-V is acceptable in these studies.

  11. New shape memory effects in semicrystalline polymeric networks

    NASA Astrophysics Data System (ADS)

    Chung, Taekwoong

    Shape memory polymers (SMPs) have attracted much research interest as a type of smart material that possesses the capacity to undergo rapid changes of their shape and size under a specific or tailored environment. Herein, we prepared semicrystalline polymers-based networks such as poly (cyclooctene) (PCO), poly (e-caprolactone) (PCL) and poly (ethylene glycol) (PEG) networks in order to explore their shape memory effects and thermomechanical properties as well as the possibilities for their applications. Interestingly, besides so-called one-shape memory effect that can be manipulated and fixed to a temporary shape under specific conditions of temperature and stress, and subsequently relax to the original shape on heating, the semicrystalline polymer networks exhibit a reversible two-way shape memory effect, revealing crystallization-induced elongation on cooling and melting-induced contraction on heating. These thermally induced reversible two-way shape memory effects were systematically explored with respect to the crosslinking density of networks and the applied stress. In order to develop a shape memory network with temperature sensing capability, we incorporated appropriately tailored chromogenic cyano-OPVs into cross-linked PCO via guest-diffusion to create phase-separated blends in which the dye's emission properties are dominated by excimer fluorescence. Heatng to the temperature above melting temperature and cooling below the crystallization temperature of PCO led to reversible optical changes through dissolution or agregation of the dye molecules. These optical changes happened in conjuction with shape changes of PCO networks. For an application of shape memory network in bone tissue engineering, we fabricated novel shape memory nanocomposite scaffolds base on PCL and nano-hydroxyapatite (nano-HAP) using thiol-ene photopolymerization and salt leaching technique. The shape memory property, morphologies and biomineralization of the scaffolds were

  12. Evidence of Universal Temperature Scaling in Self-Heated Percolating Networks.

    PubMed

    Das, Suprem R; Mohammed, Amr M S; Maize, Kerry; Sadeque, Sajia; Shakouri, Ali; Janes, David B; Alam, Muhammad A

    2016-05-11

    During routine operation, electrically percolating nanocomposites are subjected to high voltages, leading to spatially heterogeneous current distribution. The heterogeneity implies localized self-heating that may (self-consistently) reroute the percolation pathways and even irreversibly damage the material. In the absence of experiments that can spatially resolve the current distribution and a nonlinear percolation model suitable to interpret them, one relies on empirical rules and safety factors to engineer these materials. In this paper, we use ultrahigh resolution thermo-reflectance imaging, coupled with a new imaging processing technique, to map the spatial distribution ΔT(x, y; I) and histogram f(ΔT) of temperature rise due to self-heating in two types of 2D networks (percolating and copercolating). Remarkably, we find that the self-heating can be described by a simple two-parameter Weibull distribution, even under voltages high enough to reconfigure the percolation pathways. Given the generality of the phenomenological argument supporting the distribution, other percolating networks are likely to show similar stress distribution in response to sufficiently large stimuli. Furthermore, the spatial evolution of the self-heating of network was investigated by analyzing the spatial distribution and spatial correlation, respectively. An estimation of degree of hotspot clustering reveals a mechanism analogous to crystallization physics. The results should encourage nonlinear generalization of percolation models necessary for predictive engineering of nanocomposite materials.

  13. Heating value prediction for combustible fraction of municipal solid waste in Semarang using backpropagation neural network

    NASA Astrophysics Data System (ADS)

    Khuriati, Ainie; Setiabudi, Wahyu; Nur, Muhammad; Istadi, Istadi

    2015-12-01

    Backpropgation neural network was trained to predict of combustible fraction heating value of MSW from the physical composition. Waste-to-Energy (WtE) is a viable option for municipal solid waste (MSW) management. The influence of the heating value of municipal solid waste (MSW) is very important on the implementation of WtE systems. As MSW is heterogeneous material, direct heating value measurements are often not feasible. In this study an empirical model was developed to describe the heating value of the combustible fraction of municipal solid waste as a function of its physical composition of MSW using backpropagation neural network. Sampling process was carried out at Jatibarang landfill. The weight of each sorting sample taken from each discharged MSW vehicle load is 100 kg. The MSW physical components were grouped into paper wastes, absorbent hygiene product waste, styrofoam waste, HD plastic waste, plastic waste, rubber waste, textile waste, wood waste, yard wastes, kitchen waste, coco waste, and miscellaneous combustible waste. Network was trained by 24 datasets with 1200, 769, and 210 epochs. The results of this analysis showed that the correlation from the physical composition is better than multiple regression method .

  14. Effective Teacher Professionalization in Networks?

    ERIC Educational Resources Information Center

    Hofman, Roelande H.; Dijkstra, Bernadette J.

    2010-01-01

    Teacher professionalization has been focused too strongly on external experts and a one-size-fits-all set of solutions that often fail to distinguish between the needs of different teachers. This article describes a research into teacher networks that might be more successful vehicles for professional development of teachers. The results show that…

  15. Scaling Effect In Trade Network

    NASA Astrophysics Data System (ADS)

    Konar, M.; Lin, X.; Rushforth, R.; Ruddell, B. L.; Reimer, J.

    2015-12-01

    Scaling is an important issue in the physical sciences. Economic trade is increasingly of interest to the scientific community due to the natural resources (e.g. water, carbon, nutrients, etc.) embodied in traded commodities. Trade refers to the spatial and temporal redistribution of commodities, and is typically measured annually between countries. However, commodity exchange networks occur at many different scales, though data availability at finer temporal and spatial resolution is rare. Exchange networks may prove an important adaptation measure to cope with future climate and economic shocks. As such, it is essential to understand how commodity exchange networks scale, so that we can understand opportunities and roadblocks to the spatial and temporal redistribution of goods and services. To this end, we present an empirical analysis of trade systems across three spatial scales: global, sub-national in the United States, and county-scale in the United States. We compare and contrast the network properties, the self-sufficiency ratio, and performance of the gravity model of trade for these three exchange systems.

  16. Effect of the heating surface enhancement on the heat transfer coefficient for a vertical minichannel

    NASA Astrophysics Data System (ADS)

    Piasecka, Magdalena; Strąk, Kinga

    2016-03-01

    The aim of the paper is to estimate effect of the heating surface enhancement on FC-72 flow boiling heat transfer for a vertical minichannel 1.7 mm deep, 24 mm wide and 360 mm long. Two types of enhanced heating surfaces were used: one with minicavities distributed unevenly, and the other with capillary metal fibrous structure. It was to measure temperature field on the plain side of the heating surface by means of the infrared thermography and to observe the two-phase flow patterns on the enhanced foil side. The paper analyses mainly the impact of the microstructured heating surface on the heat transfer coefficient. The results are presented as heat transfer coefficient dependences on the distance along the minichannel length. The data obtained using two types of enhanced heating surfaces in experiments was compared with the data when smooth foil as the heating surface was used. The highest local values of heat transfer coefficient were obtained using enhanced foil with minicavities - in comparison to other cases. Local values of heat transfer coefficient received for capillary fibrous structure were the lowest, even compared with data obtained for smooth foil. Probably this porous structure caused local flow disturbances.

  17. Geometric Phase Effect in Heat Transport

    NASA Astrophysics Data System (ADS)

    Ren, Jie; Hanggi, Petter; Li, Baowen

    2011-03-01

    Nonlinear molecular heat-pumping devices, which operate via explicitly modulating at least two parameters, are crucial for energy control in low dimensional nano-scale systems. We have applied slow two-parameter modulations on such a molecular junctions and consequently uncovered an intrinsic heat flux contribution, additional to the known, usual dynamical heat flux (from hot to cold). This additional heat flux derives from a nontrivial geometric origin that relates to a non-vanishing, so termed finite Berry phase. It provides a free lunch for the pumped heat and even can direct heat flux against the temperature bias. In addition we are able to show that this so pumped energy exhibits a novel robust fractional quantization phenomenon. Interestingly, this additional geometric heat pump mechanism is also shown to cause a breakdown of the heat-flux fluctuation theorem, which holds true for the non-driving, stationary heat flux transfer. The validity of this theorem is guaranteed whenever (i) the geometric phase contribution vanishes and (ii) the cyclic protocol preserves the detailed balance symmetry.

  18. Simulation and optimization of a pulsating heat pipe using artificial neural network and genetic algorithm

    NASA Astrophysics Data System (ADS)

    Jokar, Ali; Godarzi, Ali Abbasi; Saber, Mohammad; Shafii, Mohammad Behshad

    2016-11-01

    In this paper, a novel approach has been presented to simulate and optimize the pulsating heat pipes (PHPs). The used pulsating heat pipe setup was designed and constructed for this study. Due to the lack of a general mathematical model for exact analysis of the PHPs, a method has been applied for simulation and optimization using the natural algorithms. In this way, the simulator consists of a kind of multilayer perceptron neural network, which is trained by experimental results obtained from our PHP setup. The results show that the complex behavior of PHPs can be successfully described by the non-linear structure of this simulator. The input variables of the neural network are input heat flux to evaporator (q″), filling ratio (FR) and inclined angle (IA) and its output is thermal resistance of PHP. Finally, based upon the simulation results and considering the heat pipe's operating constraints, the optimum operating point of the system is obtained by using genetic algorithm (GA). The experimental results show that the optimum FR (38.25 %), input heat flux to evaporator (39.93 W) and IA (55°) that obtained from GA are acceptable.

  19. Simulation and optimization of a pulsating heat pipe using artificial neural network and genetic algorithm

    NASA Astrophysics Data System (ADS)

    Jokar, Ali; Godarzi, Ali Abbasi; Saber, Mohammad; Shafii, Mohammad Behshad

    2016-01-01

    In this paper, a novel approach has been presented to simulate and optimize the pulsating heat pipes (PHPs). The used pulsating heat pipe setup was designed and constructed for this study. Due to the lack of a general mathematical model for exact analysis of the PHPs, a method has been applied for simulation and optimization using the natural algorithms. In this way, the simulator consists of a kind of multilayer perceptron neural network, which is trained by experimental results obtained from our PHP setup. The results show that the complex behavior of PHPs can be successfully described by the non-linear structure of this simulator. The input variables of the neural network are input heat flux to evaporator (q″), filling ratio (FR) and inclined angle (IA) and its output is thermal resistance of PHP. Finally, based upon the simulation results and considering the heat pipe's operating constraints, the optimum operating point of the system is obtained by using genetic algorithm (GA). The experimental results show that the optimum FR (38.25 %), input heat flux to evaporator (39.93 W) and IA (55°) that obtained from GA are acceptable.

  20. Heat sink effects on weld bead: VPPA process

    NASA Technical Reports Server (NTRS)

    Steranka, Paul O., Jr.

    1990-01-01

    An investigation into the heat sink effects due to weldment irregularities and fixtures used in the variable polarity plasma arc (VPPA) process was conducted. A basic two-dimensional model was created to represent the net heat sink effect of surplus material using Duhamel's theorem to superpose the effects of an infinite number of line heat sinks of variable strength. Parameters were identified that influence the importance of heat sink effects. A characteristic length, proportional to the thermal diffusivity of the weldment material divided by the weld torch travel rate, correlated with heat sinking observations. Four tests were performed on 2219-T87 aluminum plates to which blocks of excess material were mounted in order to demonstrate heat sink effects. Although the basic model overpredicted these effects, it correctly indicated the trends shown in the experimental study and is judged worth further refinement.

  1. Heat sink effects on weld bead: VPPA process

    NASA Technical Reports Server (NTRS)

    Steranka, Paul O., Jr.

    1989-01-01

    An investigation into the heat sink effects due to weldment irregularities and fixtures used in the variable polarity plasma arc (VPPA) process was conducted. A basic two-dimensional model was created to represent the net heat sink effect of surplus material using Duhamel's theorem to superpose the effects of an infinite number of line heat sinks of variable strength. Parameters were identified that influence the importance of heat sink effects. A characteristic length, proportional to the thermal diffusivity of the weldment material divided by the weld torch travel rate, correlated with heat sinking observations. Four tests were performed on 2219-T87 aluminum plates to which blocks of excess material were mounted in order to demonstrate heat sink effects. Although the basic model overpredicted these effects, it correctly indicated the trends shown in the experimental study and is judged worth further refinement.

  2. Artificial Neural Networks-Based Software for Measuring Heat Collection Rate and Heat Loss Coefficient of Water-in-Glass Evacuated Tube Solar Water Heaters

    PubMed Central

    Liu, Zhijian; Liu, Kejun; Li, Hao; Zhang, Xinyu; Jin, Guangya; Cheng, Kewei

    2015-01-01

    Measurements of heat collection rate and heat loss coefficient are crucial for the evaluation of in service water-in-glass evacuated tube solar water heaters. However, conventional measurement requires expensive detection devices and undergoes a series of complicated procedures. To simplify the measurement and reduce the cost, software based on artificial neural networks for measuring heat collection rate and heat loss coefficient of water-in-glass evacuated tube solar water heaters was developed. Using multilayer feed-forward neural networks with back-propagation algorithm, we developed and tested our program on the basis of 915measuredsamples of water-in-glass evacuated tube solar water heaters. This artificial neural networks-based software program automatically obtained accurate heat collection rateand heat loss coefficient using simply "portable test instruments" acquired parameters, including tube length, number of tubes, tube center distance, heat water mass in tank, collector area, angle between tubes and ground and final temperature. Our results show that this software (on both personal computer and Android platforms) is efficient and convenient to predict the heat collection rate and heat loss coefficient due to it slow root mean square errors in prediction. The software now can be downloaded from http://t.cn/RLPKF08. PMID:26624613

  3. Artificial Neural Networks-Based Software for Measuring Heat Collection Rate and Heat Loss Coefficient of Water-in-Glass Evacuated Tube Solar Water Heaters.

    PubMed

    Liu, Zhijian; Liu, Kejun; Li, Hao; Zhang, Xinyu; Jin, Guangya; Cheng, Kewei

    2015-01-01

    Measurements of heat collection rate and heat loss coefficient are crucial for the evaluation of in service water-in-glass evacuated tube solar water heaters. However, conventional measurement requires expensive detection devices and undergoes a series of complicated procedures. To simplify the measurement and reduce the cost, software based on artificial neural networks for measuring heat collection rate and heat loss coefficient of water-in-glass evacuated tube solar water heaters was developed. Using multilayer feed-forward neural networks with back-propagation algorithm, we developed and tested our program on the basis of 915 measured samples of water-in-glass evacuated tube solar water heaters. This artificial neural networks-based software program automatically obtained accurate heat collection rate and heat loss coefficient using simply "portable test instruments" acquired parameters, including tube length, number of tubes, tube center distance, heat water mass in tank, collector area, angle between tubes and ground and final temperature. Our results show that this software (on both personal computer and Android platforms) is efficient and convenient to predict the heat collection rate and heat loss coefficient due to it slow root mean square errors in prediction. The software now can be downloaded from http://t.cn/RLPKF08.

  4. Artificial Neural Networks-Based Software for Measuring Heat Collection Rate and Heat Loss Coefficient of Water-in-Glass Evacuated Tube Solar Water Heaters.

    PubMed

    Liu, Zhijian; Liu, Kejun; Li, Hao; Zhang, Xinyu; Jin, Guangya; Cheng, Kewei

    2015-01-01

    Measurements of heat collection rate and heat loss coefficient are crucial for the evaluation of in service water-in-glass evacuated tube solar water heaters. However, conventional measurement requires expensive detection devices and undergoes a series of complicated procedures. To simplify the measurement and reduce the cost, software based on artificial neural networks for measuring heat collection rate and heat loss coefficient of water-in-glass evacuated tube solar water heaters was developed. Using multilayer feed-forward neural networks with back-propagation algorithm, we developed and tested our program on the basis of 915 measured samples of water-in-glass evacuated tube solar water heaters. This artificial neural networks-based software program automatically obtained accurate heat collection rate and heat loss coefficient using simply "portable test instruments" acquired parameters, including tube length, number of tubes, tube center distance, heat water mass in tank, collector area, angle between tubes and ground and final temperature. Our results show that this software (on both personal computer and Android platforms) is efficient and convenient to predict the heat collection rate and heat loss coefficient due to it slow root mean square errors in prediction. The software now can be downloaded from http://t.cn/RLPKF08. PMID:26624613

  5. Dielectric heating effects of dual-frequency liquid crystals

    NASA Astrophysics Data System (ADS)

    Wen, Chien-Hui; Wu, Shin-Tson

    2005-06-01

    A noncontact birefringence probing method is developed to monitor the temperature rise of dual-frequency liquid crystals (DFLCs) due to the dielectric heating effect. This method allows us to determine the temperature change accurately without using a thermocouple. The dielectric heating effects of three DFLC mixtures are investigated quantitatively. By properly choosing the molecular structures, the dielectric heating effect can be minimized while keeping other desirable physical properties uncompromised.

  6. Heat Damaged Forages: Effects on Forage Quality

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Traditionally, heat damage in forages has been associated with alterations in forage protein quality as a result of Maillard reactions, and most producers and nutritionists are familiar with this concept. However, this is not necessarily the most important negative consequence of spontaneous heating...

  7. Effects of heat treatment on carbon fibers

    NASA Technical Reports Server (NTRS)

    Brown, D. Kyle; Phillips, Wayne M.

    1990-01-01

    Commercially produced carbon fibers were heat treated to graphitization temperatures. The fibers were characterized for mechanical and physical properties, including density, D0002 spacing, strength, and modulus in both the 'as received' and heat treated conditions. Mechanical property changes were correlated with the physical property changes in the fibers.

  8. Investigation on reticle heating effect induced overlay error

    NASA Astrophysics Data System (ADS)

    Lim, Mijung; Kim, Geunhak; Kim, SeoMin; Lee, Byounghoon; Kim, Seokkyun; Lim, Chang-moon; Kim, Myoungsoo; Park, Sungki

    2014-04-01

    As design rule of semiconductor decreases continuously, overlay error control gets more and more important and challenging. It is also true that On Product Overlay (OPO) of leading edge memory device shows unprecedented level of accuracy, owing to the development of precision optics, mechanic stage and alignment system with active compensation method. However, the heating of reticle and lens acts as a dominant detriment against further improvement of overlay. Reticle heating is more critical than lens heating in current advanced scanners because lens heating can be mostly compensated by feed-forward control algorithm. In recent years, the tools and technical ideas for reticle heating control are proposed and thought to reduce the reticle heating effect. Nevertheless, it is not still simple to predict the accurate heating amount and overlay. And it is required to investigate the parameters affecting reticle heating quantitatively. In this paper, the reticle pattern density and exposure dose are considered as the main contributors, and the effects are investigated through experiments. Mask set of various transmittance are prepared by changing pattern density. After exposure with various doses, overlay are measured and analyzed by comparing with reference marks exposed in heating free condition. As a result, it is discovered that even in the case of low dose and high transmittance, reticle heating is hardly avoidable. It is also shown that there is a simple relationship among reticle heating, transmittance and exposure dose. Based on this relationship, the reticle heating is thought to be predicted if the transmittance and dose are fixed.

  9. a Conceptual Model of Integrating Sensor Network and Radiative Heat Transfer Equation for Ethylene Furnace

    NASA Astrophysics Data System (ADS)

    Abas, Z. Abal; Salleh, S.; Basari, A. S. Hassan; Ibrahim, Nuzulha Khilwani

    2010-11-01

    A conceptual model of integrating the sensor network and the radiative heat transfer equation is developed and presented in this paper. The idea is to present possible deployment of sensor networks in the Ethylene furnace so that valuable input in the form of boundary value can be generated in order to produce intensity distribution and heat flux distribution. Once the location of sensor deployment has been recommended, the mesh at the physical space between the furnace wall and the reactor tube is constructed. The paper concentrates only at 2D model with only 1 U-bend reactor tube in the ethylene furnace as an initial phase of constructing a complete simulation in real furnace design.

  10. Pore-network study of bubble growth in porous media driven by heat transfer

    SciTech Connect

    Satik, C.; Yortsos, Y.C.

    1996-05-01

    We present experimental and theoretical investigations of vapor phase growth in pore-network models of porous media. Visualization experiments of boiling of ethyl alcohol in horizontal etched-glass micromodels were conducted. The vapor phase was observed to grow into a disordered pattern following a sequence of pressurization and pore-filling steps. At sufficiently small cluster sizes, growth occurred `one pore at a time,` leading to invasion percolation patterns. Single-bubble (cluster) growth was next simulated with a pore-network simulator that includes heat transfer (convection and conduction), and capillary and viscous forces, although not gravity. A boundary in the parameter space was delineated that separates patterns of growth dictated solely by capillarity (invasion percolation) from other patterns. The region of validity of invasion percolation was found to decrease as the supersaturation (heat flux), the capillary number, the thermal diffusivity, and the vapor cluster size increase. Implications to continuum models are discussed. 33 refs., 9 figs.

  11. Effects of Macromolecular Crowding on Genetic Networks

    PubMed Central

    Morelli, Marco J.; Allen, Rosalind J.; Rein ten Wolde, Pieter

    2011-01-01

    The intracellular environment is crowded with proteins, DNA, and other macromolecules. Under physiological conditions, macromolecular crowding can alter both molecular diffusion and the equilibria of bimolecular reactions and therefore is likely to have a significant effect on the function of biochemical networks. We propose a simple way to model the effects of macromolecular crowding on biochemical networks via an appropriate scaling of bimolecular association and dissociation rates. We use this approach, in combination with kinetic Monte Carlo simulations, to analyze the effects of crowding on a constitutively expressed gene, a repressed gene, and a model for the bacteriophage λ genetic switch, in the presence and absence of nonspecific binding of transcription factors to genomic DNA. Our results show that the effects of crowding are mainly caused by the shift of association-dissociation equilibria rather than the slowing down of protein diffusion, and that macromolecular crowding can have relevant and counterintuitive effects on biochemical network performance. PMID:22208186

  12. Neural network approach to prediction of temperatures around groundwater heat pump systems

    NASA Astrophysics Data System (ADS)

    Lo Russo, Stefano; Taddia, Glenda; Gnavi, Loretta; Verda, Vittorio

    2013-11-01

    A fundamental aspect in groundwater heat pump (GWHP) plant design is the correct evaluation of the thermally affected zone that develops around the injection well. This is particularly important to avoid interference with previously existing groundwater uses (wells) and underground structures. Temperature anomalies are detected through numerical methods. Computational fluid dynamic (CFD) models are widely used in this field because they offer the opportunity to calculate the time evolution of the thermal plume produced by a heat pump. The use of neural networks is proposed to determine the time evolution of the groundwater temperature downstream of an installation as a function of the possible utilization profiles of the heat pump. The main advantage of neural network modeling is the possibility of evaluating a large number of scenarios in a very short time, which is very useful for the preliminary analysis of future multiple installations. The neural network is trained using the results from a CFD model (FEFLOW) applied to the installation at Politecnico di Torino (Italy) under several operating conditions. The final results appeared to be reliable and the temperature anomalies around the injection well appeared to be well predicted.

  13. High effectiveness contour matching contact heat exchanger

    NASA Technical Reports Server (NTRS)

    Blakely, Robert L. (Inventor); Roebelen, George J., Jr. (Inventor); Davenport, Arthur K. (Inventor)

    1988-01-01

    There is a need in the art for a heat exchanger design having a flexible core providing contour matching capabilities, which compensates for manufacturing tolerance and distortion buildups, and which accordingly furnishes a relatively uniform thermal contact conductance between the core and external heat sources under essentially all operating conditions. The core of the heat exchanger comprises a top plate and a bottom plate, each having alternate rows of pins attached. Each of the pins fits into corresponding tight-fitting recesses in the opposite plate.

  14. On effectiveness and entropy generation in heat exchanger

    NASA Astrophysics Data System (ADS)

    Xiong, Daxi; Li, Zhixin; Guo, Zengyuan

    1996-12-01

    Some conceptual problems were discussed in the present paper. Firstly, according to the physical meaning of effectiveness, a new expression of effectiveness was developed by using an ideal heat exchanger model and temperature histogram method, in which the non-uniform inlet temperature profile was considered. Secondly, the relation of entropy generation number to effectiveness was studied, it was pointed out that both of them could express the perfect degree of a heat exchanger to the second thermodynamic law. Finally, to describe both quantity and quality of heat transferred in a heat exchanger, a criterion named as comprehensive thermal performance coefficient (CTPE) was presented.

  15. Gen Purpose 1-D Finite Element Network Fluid Flow Heat Transfer System Simulator

    1993-08-02

    SAFSIM (System Analysis Flow Simulator) is a FORTRAN computer program to simulate the integrated performance of systems involving fluid mechanics, heat transfer, and reactor dynamics. SAFSIM provides sufficient versatility to allow the engineering simulation of almost any system, from a backyard sprinkler system to a clustered nuclear reactor propulsion system. In addition to versatility, speed and robustness are primary SAFSIM development goals. SAFSIM contains three basic physics modules: (1) a one-dimensional finite element fluid mechanicsmore » module with multiple flow network capability; (2) a one-dimensional finite element structure heat transfer module with multiple convection and radiation exchange capability; and (3) a point reactor dynamics module with reactivity feedback and decay heat capability. SAFSIM can be used for compressible and incompressible, single-phase, multicomponent flow systems.« less

  16. Effects Of Heat Sinks On VPPA Welds

    NASA Technical Reports Server (NTRS)

    Nunes, Arthur C.; Steranka, Paul O., Jr.

    1991-01-01

    Report describes theoretical and experimental study of absorption of heat by metal blocks in contact with metal plate while plate subjected to variable-polarity plasma-arc (VPPA) welding. Purpose of study to contribute to development of comprehensive mathematical model of temperature in weld region. Also relevant to welding of thin sheets of metal to thick blocks of metal, heat treatment of metals, and hotspots in engines.

  17. Multitrophic diversity effects of network degradation.

    PubMed

    Nichols, Elizabeth; Peres, Carlos A; Hawes, Joseph E; Naeem, Shahid

    2016-07-01

    Predicting the functional consequences of biodiversity loss in realistic, multitrophic communities remains a challenge. No existing biodiversity-ecosystem function study to date has simultaneously incorporated information on species traits, network topology, and extinction across multiple trophic levels, while all three factors are independently understood as critical drivers of post-extinction network structure and function. We fill this gap by comparing the functional consequences of simulated species loss both within (monotrophic) and across (bitrophic) trophic levels, in an ecological interaction network estimated from spatially explicit field data on tropical fecal detritus producer and consumers (mammals and dung beetles). We simulated trait-ordered beetle and mammal extinction separately (monotrophic extinction) and the coextinction of beetles following mammal loss (bitrophic extinction), according to network structure. We also compared the diversity effects of bitrophic extinction models using a standard monotrophic function (the daily production or consumption of fecal detritus) and a unique bitrophic functional metric (the proportion of daily detritus production that is consumed). We found similar mono- and bitrophic diversity effects, regardless of which species traits were used to drive extinctions, yet divergent predictions when different measures of function were used. The inclusion of information on network structure had little apparent effect on the qualitative relationship between diversity and function. These results contribute to our growing understanding of the functional consequences of biodiversity from real systems and underscore the importance of species traits and realistic functional metrics to assessments of the ecosystem impacts of network degradation through species loss. PMID:27547324

  18. Multitrophic diversity effects of network degradation.

    PubMed

    Nichols, Elizabeth; Peres, Carlos A; Hawes, Joseph E; Naeem, Shahid

    2016-07-01

    Predicting the functional consequences of biodiversity loss in realistic, multitrophic communities remains a challenge. No existing biodiversity-ecosystem function study to date has simultaneously incorporated information on species traits, network topology, and extinction across multiple trophic levels, while all three factors are independently understood as critical drivers of post-extinction network structure and function. We fill this gap by comparing the functional consequences of simulated species loss both within (monotrophic) and across (bitrophic) trophic levels, in an ecological interaction network estimated from spatially explicit field data on tropical fecal detritus producer and consumers (mammals and dung beetles). We simulated trait-ordered beetle and mammal extinction separately (monotrophic extinction) and the coextinction of beetles following mammal loss (bitrophic extinction), according to network structure. We also compared the diversity effects of bitrophic extinction models using a standard monotrophic function (the daily production or consumption of fecal detritus) and a unique bitrophic functional metric (the proportion of daily detritus production that is consumed). We found similar mono- and bitrophic diversity effects, regardless of which species traits were used to drive extinctions, yet divergent predictions when different measures of function were used. The inclusion of information on network structure had little apparent effect on the qualitative relationship between diversity and function. These results contribute to our growing understanding of the functional consequences of biodiversity from real systems and underscore the importance of species traits and realistic functional metrics to assessments of the ecosystem impacts of network degradation through species loss.

  19. Numerical simulation of hyperbolic heat conduction with convection boundary conditions and pulse heating effects

    NASA Technical Reports Server (NTRS)

    Glass, David E.; Tamma, Kumar K.; Railkar, Sudhir B.

    1989-01-01

    The paper describes the numerical simulation of hyperbolic heat conduction with convection boundary conditions. The effects of a step heat loading, a sudden pulse heat loading, and an internal heat source are considered in conjunction with convection boundary conditions. Two methods of solution are presened for predicting the transient behavior of the propagating thermal disturbances. In the first method, MacCormack's predictor-corrector method is employed for integrating the hyperbolic system of equations. Next, the transfinite element method, which employs specially tailored elements, is used for accurately representing the transient response of the propagating thermal wave fronts. The agreement between the results of various numerical test cases validate the representative behavior of the thermal wave fronts. Both methods represent hyperbolic heat conduction behavior by effectively modeling the sharp discontinuities of the propagating thermal disturbances.

  20. The effect of spatiality on multiplex networks

    NASA Astrophysics Data System (ADS)

    Danziger, Michael M.; Shekhtman, Louis M.; Berezin, Yehiel; Havlin, Shlomo

    2016-08-01

    Many multiplex networks are embedded in space, with links more likely to exist between nearby nodes than distant nodes. For example, interdependent infrastructure networks can be represented as multiplex networks, where each layer has links among nearby nodes. Here, we model the effect of spatiality on the robustness of a multiplex network embedded in 2-dimensional space, where links in each layer are of variable but constrained length. Based on empirical measurements of real-world networks, we adopt exponentially distributed link lengths with characteristic length ζ. By changing ζ, we modulate the strength of the spatial embedding. When ζ → ∞, all link lengths are equally likely, and the spatiality does not affect the topology. However, when \\zeta→ 0 only short links are allowed, and the topology is overwhelmingly determined by the spatial embedding. We find that, though longer links strengthen a single-layer network, they make a multi-layer network more vulnerable. We further find that when ζ is longer than a certain critical value, \\zetac , abrupt, discontinuous transitions take place, while for \\zeta<\\zetac the transition is continuous, indicating that the risk of abrupt collapse can be eliminated if the typical link length is shorter than \\zetac .

  1. Mathematical study of probe arrangement and nanoparticle injection effects on heat transfer during cryosurgery.

    PubMed

    Mirkhalili, Seyyed Mostafa; Ramazani S A, Ahmad; Nazemidashtarjandi, Saeed

    2015-11-01

    Blood vessels, especially large vessels have a greater thermal effect on freezing tissue during cryosurgery. Vascular networks act as heat sources in tissue, and cause failure in cryosurgery and reappearance of cancer. The aim of this study is to numerically simulate the effect of probe location and multiprobe on heat transfer distribution. Furthermore, the effect of nanoparticles injection is studied. It is shown that the small probes location near large blood vessels could help to reduce the necessary time for tissue freezing. Nanoparticles injection shows that the thermal effect of blood vessel in tissue is improved. Using Au, Ag and diamond nanoparticles have the most growth of ice ball during cryosurgery. However, polytetrafluoroethylene (PTFE) nanoparticle can be used to protect normal tissue around tumor cell due to its influence on reducing heat transfer in tissue. Introduction of Au, Ag and diamond nanoparticles combined with multicryoprobe in this model causes reduction of tissue average temperature about 50% compared to the one probe. PMID:26406880

  2. Mathematical study of probe arrangement and nanoparticle injection effects on heat transfer during cryosurgery.

    PubMed

    Mirkhalili, Seyyed Mostafa; Ramazani S A, Ahmad; Nazemidashtarjandi, Saeed

    2015-11-01

    Blood vessels, especially large vessels have a greater thermal effect on freezing tissue during cryosurgery. Vascular networks act as heat sources in tissue, and cause failure in cryosurgery and reappearance of cancer. The aim of this study is to numerically simulate the effect of probe location and multiprobe on heat transfer distribution. Furthermore, the effect of nanoparticles injection is studied. It is shown that the small probes location near large blood vessels could help to reduce the necessary time for tissue freezing. Nanoparticles injection shows that the thermal effect of blood vessel in tissue is improved. Using Au, Ag and diamond nanoparticles have the most growth of ice ball during cryosurgery. However, polytetrafluoroethylene (PTFE) nanoparticle can be used to protect normal tissue around tumor cell due to its influence on reducing heat transfer in tissue. Introduction of Au, Ag and diamond nanoparticles combined with multicryoprobe in this model causes reduction of tissue average temperature about 50% compared to the one probe.

  3. Effect of Microwave Heating on Phytosterol Oxidation.

    PubMed

    Leal-Castañeda, Everth Jimena; Inchingolo, Raffaella; Cardenia, Vladimiro; Hernandez-Becerra, Josafat Alberto; Romani, Santina; Rodriguez-Estrada, María Teresa; Galindo, Hugo Sergio García

    2015-06-10

    The oxidative stability of phytosterols during microwave heating was evaluated. Two different model systems (a solid film made with a phytosterol mixture (PSF) and a liquid mixture of phytosterols and triolein (1:100, PS + TAG (triacylglycerol))) were heated for 1.5, 3, 6, 12, 20, and 30 min at 1000 W. PS degraded faster when they were microwaved alone than in the presence of TAG, following a first-order kinetic model. Up to 6 min, no phytosterol oxidation products (POPs) were generated in both systems. At 12 min of heating, the POP content reached a higher level in PSF (90.96 μg/mg of phytosterols) than in PS + TAG (22.66 μg/mg of phytosterols), but after 30 min of treatment, the opposite trend was observed. 7-Keto derivates were the most abundant POPs in both systems. The extent of phytosterol degradation depends on both the heating time and the surrounding medium, which can impact the quality and safety of the food product destined to microwave heating/cooking.

  4. Effects of network structure and routing strategy on network capacity

    NASA Astrophysics Data System (ADS)

    Chen, Zhen Yi; Wang, Xiao Fan

    2006-03-01

    The capacity of maximum end-to-end traffic flow the network is able to handle without overloading is an important index for network performance in real communication systems. In this paper, we estimate the variations of network capacity under different routing strategies for three different topologies. Simulation results reveal that the capacity depends on the underlying network structure and the capacity increases as the network becomes more homogeneous. It is also observed that the network capacity is greatly enhanced when the new traffic awareness routing strategy is adopted in each network structure.

  5. Effects of heat stress on baroreflex function in humans

    NASA Technical Reports Server (NTRS)

    Crandall, Craig G.; Cui, Jian; Wilson, Thad E.

    2003-01-01

    INTRODUCTION: Heat stress significantly reduces orthostatic tolerance in humans. The mechanism(s) causing this response remain unknown. The purpose of this review article is to present data pertaining to the hypothesis that reduced orthostatic tolerance in heat stressed individuals is a result of heat stress induced alterations in baroflex function. METHODS: In both normothermic and heat stressed conditions baroreflex responsiveness was assessed via pharmacological and non-pharmacological methods. In addition, the effects of heat stress on post-synaptic vasoconstrictor responsiveness were assessed. RESULTS: Generally, whole body heating did not alter baroreflex sensitivity defined as the gain of the linear portion of the baroreflex curve around the operating point. However, whole body heating shifted the baroreflex curve to the prevailing (i.e. elevated) heart rate and muscle sympathetic nerve activity. Finally, the heat stress impaired vasoconstrictor responses to exogenous administration of adrenergic agonists. CONCLUSION: Current data do not support the hypothesis that reduced orthostatic tolerance associated with heat stress in humans is due to impaired baroreflex responsiveness. This phenomenon may be partially due to the effects of heat stress on reducing vasoconstrictor responsiveness.

  6. Particle shape effect on heat transfer performance in an oscillating heat pipe

    PubMed Central

    2011-01-01

    The effect of alumina nanoparticles on the heat transfer performance of an oscillating heat pipe (OHP) was investigated experimentally. A binary mixture of ethylene glycol (EG) and deionized water (50/50 by volume) was used as the base fluid for the OHP. Four types of nanoparticles with shapes of platelet, blade, cylinder, and brick were studied, respectively. Experimental results show that the alumina nanoparticles added in the OHP significantly affect the heat transfer performance and it depends on the particle shape and volume fraction. When the OHP was charged with EG and cylinder-like alumina nanoparticles, the OHP can achieve the best heat transfer performance among four types of particles investigated herein. In addition, even though previous research found that these alumina nanofluids were not beneficial in laminar or turbulent flow mode, they can enhance the heat transfer performance of an OHP. PMID:21711830

  7. Effect of Heat Exchanger Material and Fouling on Thermoelectric Exhaust Heat Recovery

    SciTech Connect

    Love, Norman; Szybist, James P; Sluder, Scott

    2011-01-01

    This study is conducted in an effort to better understand and improve the performance of thermoelectric heat recovery systems for automotive use. For this purpose an experimental investigation of thermoelectrics in contact with clean and fouled heat exchangers of different materials is performed. The thermoelectric devices are tested on a bench-scale thermoelectric heat recovery apparatus that simulates automotive exhaust. The thermoelectric apparatus consists of a series of thermoelectric generators contacting a hot-side and a cold-side heat exchanger. The thermoelectric devices are tested with two different hot-side heat exchanger materials, stainless steel and aluminum, and at a range of simulated exhaust gas flowrates (40 to 150 slpm), exhaust gas temperatures (240 C and 280 C), and coolant-side temperatures (40 C and 80 C). It is observed that for higher exhaust gas flowrates, thermoelectric power output increases while overall system efficiency decreases. Degradation of the effectiveness of the EGR-type heat exchangers over a period of driving is also simulated by exposing the heat exchangers to diesel engine exhaust under thermophoretic conditions to form a deposit layer. For the fouled EGR-type heat exchangers, power output and system efficiency is observed to be significantly lower for all conditions tested. The study found, however, that heat exchanger material is the dominant factor in the ability of the system to convert heat to electricity with thermoelectric generators. This finding is thought to be unique to the heat exchangers used for this study, and not a universal trend for all system configurations.

  8. Evaluating the Effectiveness of Community-Based Dementia Care Networks: The Dementia Care Networks' Study

    ERIC Educational Resources Information Center

    Lemieux-Charles, Louis; Chambers, Larry W.; Cockerill, Rhonda; Jaglal, Susan; Brazil, Kevin; Cohen, Carole; LeClair, Ken; Dalziel, Bill; Schulman, Barbara

    2005-01-01

    Purpose: The Dementia Care Networks' Study examined the effectiveness of four community-based, not-for-profit dementia networks. The study involved assessing the relationship between the types of administrative and service-delivery exchanges that occurred among the networked agencies and the network members' perception of the effectiveness of…

  9. Perceived heat stress and health effects on construction workers

    PubMed Central

    Dutta, Priya; Rajiva, Ajit; Andhare, Dileep; Azhar, Gulrez Shah; Tiwari, Abhiyant; Sheffield, Perry

    2015-01-01

    Introduction: Increasing heat waves-particularly in urban areas where construction is most prevalent, highlight a need for heat exposure assessment of construction workers. This study aims to characterize the effects of heat on construction workers from a site in Gandhinagar. Materials and Methods: This study involved a mixed methods approach consisting of a cross sectional survey with anthropometric measurements (n = 219) and four focus groups with construction workers, as well as environmental measurements of heat stress exposure at a construction site. Survey data was collected in two seasons i.e., summer and winter months, and heat illness and symptoms were compared between the two time periods. Thematic coding of focus group data was used to identify vulnerability factors and coping mechanisms of the workers. Heat stress, recorded using a wet bulb globe temperature monitor, was compared to international safety standards. Results: The survey findings suggest that heat-related symptoms increased in summer; 59% of all reports in summer were positive for symptoms (from Mild to Severe) as compared to 41% in winter. Focus groups revealed four dominant themes: (1) Non-occupational stressors compound work stressors; (2) workers were particularly attuned to the impact of heat on their health; (3) workers were aware of heat-related preventive measures; and (4) few resources were currently available to protect workers from heat stress. Working conditions often exceed international heat stress safety thresholds. Female workers and new employees might be at increased risk of illness or injury. Conclusion: This study suggests significant health impacts on construction workers from heat stress exposure in the workplace, showed that heat stress levels were higher than those prescribed by international standards and highlights the need for revision of work practices, increased protective measures, and possible development of indigenous work safety standards for heat exposure

  10. Effect of Heat Acclimation on Sweat Minerals

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Purpose: This study examined the impact of 10-days of exercise-heat acclimation on sweat mineral concentrations. Methods: Eight male subjects walked on a treadmill at 1.56 m/sec, 4% grade for 100 continuous minutes or until rectal temperature reached 39.5°C on 10 consecutive days in an environmenta...

  11. Research on heat sensing effect along meridian of Chinese medicine

    NASA Astrophysics Data System (ADS)

    Xu, Yun-xiang; Li, Li-jun; Chen, Gui-zhen

    2012-03-01

    Photonics is a science which research light quantum as the carrier for energy and information. Photonic technology in the meridian and acupoints research has shown the unique advantages, by which the microcosmic material basis and macroscopic phenomena research can be integrated to interpret the occurrence of propagated sensation along meridian and its underling mechanism. This paper focuses on the investigation on heat sensing action along the meridian by photonic technology. The four items of heat sensing action were discussed, i.e. thermo-effects, heat sensing capability, laser induced heat effect, underling mechanism on heat sensing effect along the meridian. The authors point out that photonic technology, e.g. photonic imaging, and infrared spectrum analysis, biological photons detection and laser Doppler application, can achieve purpose of in vivo, dynamic, and multiple comparable studies. Thereby the effect of heat sensing along meridian can be detected and illustrated by the use of natural science. Heat information can be investigated to analyze the relationship between zang-fu organs, meridians, and the functional characteristics of the meridian. Hence, the effect of heat sensing along the meridian is the break point of the research of photonics in the meridian which is beneficial to further study the meridian optics.

  12. Research on heat sensing effect along meridian of Chinese medicine

    NASA Astrophysics Data System (ADS)

    Xu, Yun-xiang; Li, Li-jun; Chen, Gui-zhen

    2011-11-01

    Photonics is a science which research light quantum as the carrier for energy and information. Photonic technology in the meridian and acupoints research has shown the unique advantages, by which the microcosmic material basis and macroscopic phenomena research can be integrated to interpret the occurrence of propagated sensation along meridian and its underling mechanism. This paper focuses on the investigation on heat sensing action along the meridian by photonic technology. The four items of heat sensing action were discussed, i.e. thermo-effects, heat sensing capability, laser induced heat effect, underling mechanism on heat sensing effect along the meridian. The authors point out that photonic technology, e.g. photonic imaging, and infrared spectrum analysis, biological photons detection and laser Doppler application, can achieve purpose of in vivo, dynamic, and multiple comparable studies. Thereby the effect of heat sensing along meridian can be detected and illustrated by the use of natural science. Heat information can be investigated to analyze the relationship between zang-fu organs, meridians, and the functional characteristics of the meridian. Hence, the effect of heat sensing along the meridian is the break point of the research of photonics in the meridian which is beneficial to further study the meridian optics.

  13. A neural network to retrieve the mesoscale instantaneous latent heat flux over oceans from SSM/I observations

    NASA Technical Reports Server (NTRS)

    Bourras, D.; Eymard, L.; Liu, W. T.

    2000-01-01

    The turbulent latent and sensible heat fluxes are necessary to study heat budget of the upper ocean or initialize ocean general circulation models. In order to retrieve the latent heat flux from satellite observations authors mostly use a bulk approximation of the flux whose parameters are derived from different instrument. In this paper, an approach based on artificial neural networks is proposed and compared to the bulk method on a global data set and 3 local data sets.

  14. A Classroom Demonstration for Teaching Network Effects

    ERIC Educational Resources Information Center

    Sawler, James

    2007-01-01

    The introduction of the concept of network effects is useful at the principles level to facilitate discussions of the determinants of monopoly, the need for standards in high-tech industries, and the general complexity of real-world competition. The author describes a demonstration and an extension that help students understand how consumers make…

  15. A Comprehensive Flow, Heat and Mass Transport Uncertainty Quantification in Discrete Fracture Network Systems

    NASA Astrophysics Data System (ADS)

    Ezzedine, S. M.

    2010-12-01

    Fractures and fracture networks are the principle pathways for migration of water, heat and mass in enhanced geothermal systems, oil and gas reservoirs, CO2 leakage from saline aquifers, and radioactive and toxic industrial wastes from underground storage repositories. A major issue to overcome when characterizing a fractured reservoir is that of data limitation due to accessibility and affordability. Moreover, the ability to map discontinuities in the rock with available geological and geophysical tools tends to decrease particularly as the scale of the discontinuity goes down. Geological characterization data include measurements of fracture density, orientation, extent, and aperture, and are based on analysis of outcrops, borehole optical and acoustic televiewer logs, aerial photographs, and core samples among others. All of these measurements are taken at the field scale through a very sparse limited number of deep boreholes. These types of data are often reduced to probability distributions function for predictive modeling and simulation in a stochastic framework such as stochastic discrete fracture network. Stochastic discrete fracture network models enable, through Monte Carlo realizations and simulations, for probabilistic assessment of flow and transport phenomena that are not adequately captured using continuum models. Despite the fundamental uncertainties inherited within the probabilistic reduction of the sparse data collected, very little work has been conducted on quantifying uncertainty on the reduced probabilistic distribution functions. In the current study, using nested Monte Carlo simulations, we present the impact of parameter uncertainties of the distribution functions that characterize discrete fracture networks on the flow, heat and mass transport. Numerical results of first, second and third moments, normalized to a base case scenario, are presented and compared to theoretical results extended from percolation theory.

  16. Double-effect absorption heat pump, phase 3

    NASA Astrophysics Data System (ADS)

    Cook, F. B.; Cremean, S. P.; Jatana, S. C.; Johnson, R. A.; Malcosky, N. D.

    1987-06-01

    The RD&D program has resulted in design, development and testing of a packaged prototype double-effect generator cycle absorption gas heat pump for the residential and small commercial markets. The 3RT heat pump prototype has demonstrated a COPc of 0.82 and a COPh of 1.65 at ARI rating conditions. The heat pump prototype includes a solid state control system with built-in diagnostics. The absorbent/refrigerant solution thermophysical properties were completely characterized. Commercially available materials of construction were identified for all heat pump components. A corrosion inhibitor was identified and tested in both static and dynamic environments. The safety of the heat pump was analyzed by using two analytical approaches. Pioneer Engineering estimated the factory standard cost to produce the 3RT heat pump at $1,700 at a quantity of 50,000 units/year. One United States patent was allowed covering the heat pump technology, and two divisional applications and three Continuation-in-Park Applications were filed with the U.S.P.T.O. Corresponding patent coverage was applied for in Canada, the EEC, Australia, and Japan. Testing of the prototype heat pump is continuing, as are life tests of multiple pump concepts amd long-term dynamic corrosion tests. Continued development and commercialization of gas absorption heat pumps based on the technology are recommended.

  17. Beneficial effects of microwave-assisted heating versus conventional heating in noble metal nanoparticle synthesis.

    PubMed

    Dahal, Naween; García, Stephany; Zhou, Jiping; Humphrey, Simon M

    2012-11-27

    An extensive comparative study of the effects of microwave versus conventional heating on the nucleation and growth of near-monodisperse Rh, Pd, and Pt nanoparticles has revealed distinct and preferential effects of the microwave heating method. A one-pot synthetic method has been investigated, which combines nucleation and growth in a single reaction via precise control over the precursor addition rate. Using this method, microwave-assisted heating enables the convenient preparation of polymer-capped nanoparticles with improved monodispersity, morphological control, and higher crystallinity, compared with samples heated conventionally under otherwise identical conditions. Extensive studies of Rh nanoparticle formation reveal fundamental differences during the nucleation phase that is directly dependent on the heating method; microwave irradiation was found to provide more uniform seeds for the subsequent growth of larger nanostructures of desired size and surface structure. Nanoparticle growth kinetics are also markedly different under microwave heating. While conventional heating generally yields particles with mixed morphologies, microwave synthesis consistently provides a majority of tetrahedral particles at intermediate sizes (5-7 nm) or larger cubes (8+ nm) upon further growth. High-resolution transmission electron microscopy indicates that Rh seeds and larger nanoparticles obtained from microwave-assisted synthesis are more highly crystalline and faceted versus their conventionally prepared counterparts. Microwave-prepared Rh nanoparticles also show approximately twice the catalytic activity of similar-sized conventionally prepared particles, as demonstrated in the vapor-phase hydrogenation of cyclohexene. Ligand exchange reactions to replace polymer capping agents with molecular stabilizing agents are also easily facilitated under microwave heating, due to the excitation of polar organic moieties; the ligand exchange proceeds with excellent retention of

  18. Numerical analysis of heat input effects in thermography

    SciTech Connect

    Tossell, D.A.

    1987-06-01

    A numerical model, suited for use on microcomputers, has been developed to examine the effect of heat input function on surface temperature contrast for passive thermographic NDE. Single and double step input functions have been compared, and the effects of varying pulse length and power, defect condition, defect depth to diameter ratio, and maximum allowed front face temperature rise examined. Results indicate that a two-step heat input function enhances the generated surface temperature contrast by up to 10% over the single pulse and compares well with that generated by contact heating.

  19. Quantification of palaeoclimatic effects on heat flow in the Paris basin

    NASA Astrophysics Data System (ADS)

    Dentzer, Jacques; Lopez, Simon; Violette, Sophie; Bruel, Dominique

    2015-04-01

    Deep geothermal resources of the Paris basin have been harnessed for more than 40 years with nearly 40 operating plants supplying heat to district networks in the Parisian suburbs. The target of all these operations is the deep "Dogger" aquifer. Though these areas are densely exploited, no thermal breakthrough has been observed yet, except for a few isolated cases. As new geothermal projects are currently scheduled, heat transfers and thermal anomalies are now quantified considering the whole sedimentary pile. At this scale, thermal profiles are particularly relevant to discriminate different possible causes for the observed temperature and heat flow anomalies. Based on 10 thermal profiles in the centre of the Paris basin, a mean heat flow profile is reassessed. For each geological formation, a mean thermal gradient is estimated and heat flow is calculated with an averaged formation thermal conductivity. A simple 1D conductive numerical model is then set up with 19 sedimentary layers and a bedrock layer. Palaeoclimatic effects are quantified by testing different published temperature scenarios. These scenarios cover time scales ranging from 65 ky to 5 My. Although the uncertainty on heat flow derived from thermal profiles is around +/- 15 mW/m2, the model reproduces satisfactorily the main heat flow anomaly present in the upper part of the basin, with heat flow decreasing from 85 mW/m2 at 1200 m depth to less than 60 mW/m2 at the surface. Consequently, climatic variations over a long period of time (5 My scenario) seem enough to reproduce this anomaly correctly, which was previously attributed to convective effects. Yet, smaller scale heat flow fluctuations match aquifer levels exactly and are probably related to (relatively) short time convective water transfers at the basin scale.

  20. Equilibrium & Nonequilibrium Fluctuation Effects in Biopolymer Networks

    NASA Astrophysics Data System (ADS)

    Kachan, Devin Michael

    speculate that cells take advantage of this equilibrium effect by tuning near the transition point, where small changes in free cross-linker density will affect large structural rearrangements between free filament networks and networks of bundles. Cells are naturally found far from equilibrium, where the active influx of energy from ATP consumption controls the dynamics. Motor proteins actively generate forces within biopolymer networks, and one may ask how these differ from the random stresses characteristic of equilibrium fluctuations. Besides the trivial observation that the magnitude is independent of temperature, I find that the processive nature of the motors creates a temporally correlated, or colored, noise spectrum. I model the network with a nonlinear scalar elastic theory in the presence of active driving, and study the long distance and large scale properties of the system with renormalization group techniques. I find that there is a new critical point associated with diverging correlation time, and that the colored noise produces novel frequency dependence in the renormalized transport coefficients. Finally, I study marginally elastic solids which have vanishing shear modulus due to the presence of soft modes, modes with zero deformation cost. Although network coordination is a useful metric for determining the mechanical response of random spring networks in mechanical equilibrium, it is insufficient for describing networks under external stress. In particular, under-constrained networks which are fluid-like at zero load will dynamically stiffen at a critical strain, as observed in numerical simulations and experimentally in many biopolymer networks. Drawing upon analogies to the stress induced unjamming of emulsions, I develop a kinetic theory to explain the rigidity transition in spring and filament networks. Describing the dynamic evolution of non-affine deformation via a simple mechanistic picture, I recover the emergent nonlinear strain

  1. Sliding bubble dynamics and the effects on surface heat transfer

    NASA Astrophysics Data System (ADS)

    Donnelly, B.; Robinson, A. J.; Delauré, Y. M. C.; Murray, D. B.

    2012-11-01

    An investigation into the effects of a single sliding air bubble on heat transfer from a submerged, inclined surface has been undertaken. Existing literature has shown that both vapour and gas bubbles can increase heat transfer rates from adjacent heated surfaces. However, the mechanisms involved are complex and dynamic and in some cases poorly understood. The present study utilises high speed, high resolution, infrared thermography and video photography to measure two dimensional surface heat transfer and three dimensional bubble position and shape. This provides a unique insight into the complex interactions at the heated surface. Bubbles of volume 0.05, 0.1, 0.2 and 0.4 ml were released onto a surface inclined at 30 degrees to horizontal. Results confirmed that sliding bubbles can enhance heat transfer rates up to a factor of 9 and further insight was gained about the mechanisms behind this phenomenon. The enhancement effects were observed over large areas and persisted for a long duration with the bubble exhibiting complex shape and path oscillations. It is believed that the periodic wake structure present behind the sliding bubble affects the bubble motion and is responsible for the heat transfer effects observed. The nature of this wake is proposed to be that of a chain of horseshoe vortices.

  2. Effects of gas bubble production on heat transfer from a volumetrically heated liquid pool

    NASA Astrophysics Data System (ADS)

    Bull, Geoffrey R.

    Aqueous solutions of uranium salts may provide a new supply chain to fill potential shortfalls in the availability of the most common radiopharmaceuticals currently in use worldwide, including Tc99m which is a decay product of Mo99. The fissioning of the uranium in these solutions creates Mo99 but also generates large amounts of hydrogen and oxygen from the radiolysis of the water. When the dissolved gases reach a critical concentration, bubbles will form in the solution. Bubbles in the solution affect both the fission power and the heat transfer out of the solution. As a result, for safety and production calculations, the effects of the bubbles on heat transfer must be understood. A high aspect ratio tank was constructed to simulate a section of an annulus with heat exchangers on the inner and outer steel walls to provide cooling. Temperature measurements via thermocouples inside the tank and along the outside of the steel walls allowed the calculation of overall and local heat transfer coefficients. Different air injection manifolds allowed the exploration of various bubble characteristics and patterns on heat transfer from the pool. The manifold type did not appear to have significant impact on the bubble size distributions in water. However, air injected into solutions of magnesium sulfate resulted in smaller bubble sizes and larger void fractions than those in water at the same injection rates. One dimensional calculations provide heat transfer coefficient values as functions of the superficial gas velocity in the pool.

  3. Added effect of heat wave on mortality in Seoul, Korea

    NASA Astrophysics Data System (ADS)

    Lee, Won Kyung; Lee, Hye Ah; Lim, Youn Hee; Park, Hyesook

    2016-05-01

    A heat wave could increase mortality owing to high temperature. However, little is known about the added (duration) effect of heat wave from the prolonged period of high temperature on mortality and different effect sizes depending on the definition of heat waves and models. A distributed lag non-linear model with a quasi-Poisson distribution was used to evaluate the added effect of heat wave on mortality after adjusting for long-term and intra-seasonal trends and apparent temperature. We evaluated the cumulative relative risk of the added wave effect on mortality on lag days 0-30. The models were constructed using nine definitions of heat wave and two relationships (cubic spline and linear threshold model) between temperature and mortality to leave out the high temperature effect. Further, we performed sensitivity analysis to evaluate the changes in the effect of heat wave on mortality according to the different degrees of freedom for time trend and cubic spline of temperature. We found that heat wave had the added effect from the prolonged period of high temperature on mortality and it was considerable in the aspect of cumulative risk because of the lagged influence. When heat wave was defined with a threshold of 98th percentile temperature and ≥2, 3, and 4 consecutive days, mortality increased by 14.8 % (7.5-22.6, 95 % confidence interval (CI)), 18.1 % (10.8-26.0, 95 % CI), 18.1 % (10.7-25.9, 95 % CI), respectively, in cubic spline model. When it came to the definitions of 90th and 95th percentile, the risk increase in mortality declined to 3.7-5.8 % and 8.6-11.3 %, respectively. This effect was robust to the flexibility of the model for temperature and time trend, while the definitions of a heat wave were critical in estimating its relationship with mortality. This finding could help deepen our understanding and quantifying of the relationship between heat wave and mortality and select an appropriate definition of heat wave and temperature model in the future

  4. Added effect of heat wave on mortality in Seoul, Korea.

    PubMed

    Lee, Won Kyung; Lee, Hye Ah; Lim, Youn Hee; Park, Hyesook

    2016-05-01

    A heat wave could increase mortality owing to high temperature. However, little is known about the added (duration) effect of heat wave from the prolonged period of high temperature on mortality and different effect sizes depending on the definition of heat waves and models. A distributed lag non-linear model with a quasi-Poisson distribution was used to evaluate the added effect of heat wave on mortality after adjusting for long-term and intra-seasonal trends and apparent temperature. We evaluated the cumulative relative risk of the added wave effect on mortality on lag days 0-30. The models were constructed using nine definitions of heat wave and two relationships (cubic spline and linear threshold model) between temperature and mortality to leave out the high temperature effect. Further, we performed sensitivity analysis to evaluate the changes in the effect of heat wave on mortality according to the different degrees of freedom for time trend and cubic spline of temperature. We found that heat wave had the added effect from the prolonged period of high temperature on mortality and it was considerable in the aspect of cumulative risk because of the lagged influence. When heat wave was defined with a threshold of 98th percentile temperature and ≥2, 3, and 4 consecutive days, mortality increased by 14.8 % (7.5-22.6, 95 % confidence interval (CI)), 18.1 % (10.8-26.0, 95 % CI), 18.1 % (10.7-25.9, 95 % CI), respectively, in cubic spline model. When it came to the definitions of 90th and 95th percentile, the risk increase in mortality declined to 3.7-5.8 % and 8.6-11.3 %, respectively. This effect was robust to the flexibility of the model for temperature and time trend, while the definitions of a heat wave were critical in estimating its relationship with mortality. This finding could help deepen our understanding and quantifying of the relationship between heat wave and mortality and select an appropriate definition of heat wave and temperature model in the future

  5. Added effect of heat wave on mortality in Seoul, Korea.

    PubMed

    Lee, Won Kyung; Lee, Hye Ah; Lim, Youn Hee; Park, Hyesook

    2016-05-01

    A heat wave could increase mortality owing to high temperature. However, little is known about the added (duration) effect of heat wave from the prolonged period of high temperature on mortality and different effect sizes depending on the definition of heat waves and models. A distributed lag non-linear model with a quasi-Poisson distribution was used to evaluate the added effect of heat wave on mortality after adjusting for long-term and intra-seasonal trends and apparent temperature. We evaluated the cumulative relative risk of the added wave effect on mortality on lag days 0-30. The models were constructed using nine definitions of heat wave and two relationships (cubic spline and linear threshold model) between temperature and mortality to leave out the high temperature effect. Further, we performed sensitivity analysis to evaluate the changes in the effect of heat wave on mortality according to the different degrees of freedom for time trend and cubic spline of temperature. We found that heat wave had the added effect from the prolonged period of high temperature on mortality and it was considerable in the aspect of cumulative risk because of the lagged influence. When heat wave was defined with a threshold of 98th percentile temperature and ≥2, 3, and 4 consecutive days, mortality increased by 14.8 % (7.5-22.6, 95 % confidence interval (CI)), 18.1 % (10.8-26.0, 95 % CI), 18.1 % (10.7-25.9, 95 % CI), respectively, in cubic spline model. When it came to the definitions of 90th and 95th percentile, the risk increase in mortality declined to 3.7-5.8 % and 8.6-11.3 %, respectively. This effect was robust to the flexibility of the model for temperature and time trend, while the definitions of a heat wave were critical in estimating its relationship with mortality. This finding could help deepen our understanding and quantifying of the relationship between heat wave and mortality and select an appropriate definition of heat wave and temperature model in the future

  6. Heat sink effects in variable polarity plasma arc welding

    NASA Technical Reports Server (NTRS)

    Abdelmessih, Amanie N.

    1991-01-01

    The Space Shuttle External Tank is fabricated by the variable polarity plasma arc (VPPA) welding process. In VPPA welding, a noble gas, usually argon, is directed through an arc to emerge from the torch as a hot plasma jet. This jet is surrounded by a shielding gas, usually helium, to protect the weld from contamination with air. The high velocity, hot plasma jet completely penetrates the workpiece (resembling a line heat source) when operated in the 'keyhole' mode. The metal melts on touching the side of the jet, as the torch travels in the perpendicular direction to the direction of the jet, and melted metal moves around the plasma jet in the keyhole forming a puddle which solidifies behind the jet. Heat sink effects are observed when there are irregularities in the workpiece configuration, especially, if these irregularities are close to the weld bead. These heat sinks affect the geometry of the weld bead, i.e., in extreme cases they could cause defects such as incomplete fusion. Also, different fixtures seem to have varying heat sink effects. The objective of this research is to study the effect of irregularities in workpiece configuration and fixture differences (heat sink effects) on the weld bead geometry with the ultimate objective to compensate for the heat sink effects and achieve a perfect weld. Experiments were performed on different workpiece geometries and compared to approximate models.

  7. RESTful M2M gateway for remote wireless monitoring for district central heating networks.

    PubMed

    Cheng, Bo; Wei, Zesan

    2014-11-27

    In recent years, the increased interest in energy conservation and environmental protection, combined with the development of modern communication and computer technology, has resulted in the replacement of distributed heating by central heating in urban areas. This paper proposes a Representational State Transfer (REST) Machine-to-Machine (M2M) gateway for wireless remote monitoring for a district central heating network. In particular, we focus on the resource-oriented RESTful M2M gateway architecture, and present an uniform devices abstraction approach based on Open Service Gateway Initiative (OSGi) technology, and implement the resource mapping mechanism between resource address mapping mechanism between RESTful resources and the physical sensor devices, and present the buffer queue combined with polling method to implement the data scheduling and Quality of Service (QoS) guarantee, and also give the RESTful M2M gateway open service Application Programming Interface (API) set. The performance has been measured and analyzed. Finally, the conclusions and future work are presented.

  8. RESTful M2M Gateway for Remote Wireless Monitoring for District Central Heating Networks

    PubMed Central

    Cheng, Bo; Wei, Zesan

    2014-01-01

    In recent years, the increased interest in energy conservation and environmental protection, combined with the development of modern communication and computer technology, has resulted in the replacement of distributed heating by central heating in urban areas. This paper proposes a Representational State Transfer (REST) Machine-to-Machine (M2M) gateway for wireless remote monitoring for a district central heating network. In particular, we focus on the resource-oriented RESTful M2M gateway architecture, and present an uniform devices abstraction approach based on Open Service Gateway Initiative (OSGi) technology, and implement the resource mapping mechanism between resource address mapping mechanism between RESTful resources and the physical sensor devices, and present the buffer queue combined with polling method to implement the data scheduling and Quality of Service (QoS) guarantee, and also give the RESTful M2M gateway open service Application Programming Interface (API) set. The performance has been measured and analyzed. Finally, the conclusions and future work are presented. PMID:25436650

  9. RESTful M2M gateway for remote wireless monitoring for district central heating networks.

    PubMed

    Cheng, Bo; Wei, Zesan

    2014-01-01

    In recent years, the increased interest in energy conservation and environmental protection, combined with the development of modern communication and computer technology, has resulted in the replacement of distributed heating by central heating in urban areas. This paper proposes a Representational State Transfer (REST) Machine-to-Machine (M2M) gateway for wireless remote monitoring for a district central heating network. In particular, we focus on the resource-oriented RESTful M2M gateway architecture, and present an uniform devices abstraction approach based on Open Service Gateway Initiative (OSGi) technology, and implement the resource mapping mechanism between resource address mapping mechanism between RESTful resources and the physical sensor devices, and present the buffer queue combined with polling method to implement the data scheduling and Quality of Service (QoS) guarantee, and also give the RESTful M2M gateway open service Application Programming Interface (API) set. The performance has been measured and analyzed. Finally, the conclusions and future work are presented. PMID:25436650

  10. A mathematics for medicine: The Network Effect

    PubMed Central

    West, Bruce J.

    2014-01-01

    The theory of medicine and its complement systems biology are intended to explain the workings of the large number of mutually interdependent complex physiologic networks in the human body and to apply that understanding to maintaining the functions for which nature designed them. Therefore, when what had originally been made as a simplifying assumption or a working hypothesis becomes foundational to understanding the operation of physiologic networks it is in the best interests of science to replace or at least update that assumption. The replacement process requires, among other things, an evaluation of how the new hypothesis affects modern day understanding of medical science. This paper identifies linear dynamics and Normal statistics as being such arcane assumptions and explores some implications of their retirement. Specifically we explore replacing Normal with fractal statistics and examine how the latter are related to non-linear dynamics and chaos theory. The observed ubiquity of inverse power laws in physiology entails the need for a new calculus, one that describes the dynamics of fractional phenomena and captures the fractal properties of the statistics of physiological time series. We identify these properties as a necessary consequence of the complexity resulting from the network dynamics and refer to them collectively as The Network Effect. PMID:25538622

  11. A mathematics for medicine: The Network Effect.

    PubMed

    West, Bruce J

    2014-01-01

    The theory of medicine and its complement systems biology are intended to explain the workings of the large number of mutually interdependent complex physiologic networks in the human body and to apply that understanding to maintaining the functions for which nature designed them. Therefore, when what had originally been made as a simplifying assumption or a working hypothesis becomes foundational to understanding the operation of physiologic networks it is in the best interests of science to replace or at least update that assumption. The replacement process requires, among other things, an evaluation of how the new hypothesis affects modern day understanding of medical science. This paper identifies linear dynamics and Normal statistics as being such arcane assumptions and explores some implications of their retirement. Specifically we explore replacing Normal with fractal statistics and examine how the latter are related to non-linear dynamics and chaos theory. The observed ubiquity of inverse power laws in physiology entails the need for a new calculus, one that describes the dynamics of fractional phenomena and captures the fractal properties of the statistics of physiological time series. We identify these properties as a necessary consequence of the complexity resulting from the network dynamics and refer to them collectively as The Network Effect. PMID:25538622

  12. Pressure and heat flux effects on the heat transfer characteristics of liquid methane

    NASA Astrophysics Data System (ADS)

    Garcia, Chance P.

    The heat transfer effects on liquid methane are investigated with the use of a carbo-thermal rig at the Center for Space Exploration Technology Research (cSETR) located at the University of Texas at El Paso (UTEP). The cSETR carbo-thermal rig design approach is presented along with the design of a methane condensing mobile unit (MCMU) to supply the laboratory and rig with liquid methane. The proposed research will generate useful insight in to heat transfer coefficient behavior, non-dimensional correlations, different flow conditions, varied inlet conditions, and varied heat flux for a subscale test article applicable to a regenerative cooled rocket engine cooling channel. The data found will also improve the knowledge base for liquid methane and non-toxic propulsion. Planned test parameters are from 1.03 to 2.07 MPa (150 to 300 psi) supply tank pressure, and 3.9 to 19 MW/m2 (2.39 to 11.6 Btu/in2-s). Presented are transient and steady state heat transfer response results depicting transient and steady state heat transfer effects tested at turbulent Reynolds numbers (15000 to 360000).

  13. Effects of aqueous humor hydrodynamics on human eye heat transfer under external heat sources.

    PubMed

    Tiang, Kor L; Ooi, Ean H

    2016-08-01

    The majority of the eye models developed in the late 90s and early 00s considers only heat conduction inside the eye. This assumption is not entirely correct, since the anterior and posterior chambers are filled aqueous humor (AH) that is constantly in motion due to thermally-induced buoyancy. In this paper, a three-dimensional model of the human eye is developed to investigate the effects AH hydrodynamics have on the human eye temperature under exposure to external heat sources. If the effects of AH flow are negligible, then future models can be developed without taking them into account, thus simplifying the modeling process. Two types of external thermal loads are considered; volumetric and surface irradiation. Results showed that heat convection due to AH flow contributes to nearly 95% of the total heat flow inside the anterior chamber. Moreover, the circulation inside the anterior chamber can cause an upward shift of the location of hotspot. This can have significant consequences to our understanding of heat-induced cataractogenesis.

  14. Effects of aqueous humor hydrodynamics on human eye heat transfer under external heat sources.

    PubMed

    Tiang, Kor L; Ooi, Ean H

    2016-08-01

    The majority of the eye models developed in the late 90s and early 00s considers only heat conduction inside the eye. This assumption is not entirely correct, since the anterior and posterior chambers are filled aqueous humor (AH) that is constantly in motion due to thermally-induced buoyancy. In this paper, a three-dimensional model of the human eye is developed to investigate the effects AH hydrodynamics have on the human eye temperature under exposure to external heat sources. If the effects of AH flow are negligible, then future models can be developed without taking them into account, thus simplifying the modeling process. Two types of external thermal loads are considered; volumetric and surface irradiation. Results showed that heat convection due to AH flow contributes to nearly 95% of the total heat flow inside the anterior chamber. Moreover, the circulation inside the anterior chamber can cause an upward shift of the location of hotspot. This can have significant consequences to our understanding of heat-induced cataractogenesis. PMID:27340100

  15. The Effects of Heating Methods on Infrared Thermography

    NASA Astrophysics Data System (ADS)

    Mercer, A. Scott; Klinkhachorn, P.; Halabe, Udaya B.; GangaRao, Hota V. S.

    2007-03-01

    Infrared (IR) Thermography is a good way of detecting air filled defects in FRP decks. When heat is applied to the deck surface, the material over the air void heats up faster and becomes hotter than the surrounding area and an IR camera can distinguish this defective area from a sound area in the deck based on surface temperature measurements. Since this technique requires application of heat in order to produce results, it seems only logical that one should research the effects of different heating types on the defect analysis. For this study, various heat sources; such as the sun, a 5000 BTU quartz electric heater, a 9000 BTU propane convection heater, and a 35000 BTU forced air propane heater, were used to heat up an FRP deck specimen with built-in defects for IR analysis. Different heating times were used to determine the effects on the accuracy and the total elapsed time involved in seeing a defect in the resultant IR images. A few methods, such as CO2 cooling, for decreasing the time it takes to see the defect in the image were also explored.

  16. Heat capacity of water: A signature of nuclear quantum effects

    NASA Astrophysics Data System (ADS)

    Vega, C.; Conde, M. M.; McBride, C.; Abascal, J. L. F.; Noya, E. G.; Ramirez, R.; Sesé, L. M.

    2010-01-01

    In this note we present results for the heat capacity at constant pressure for the TIP4PQ/2005 model, as obtained from path-integral simulations. The model does a rather good job of describing both the heat capacity of ice Ih and of liquid water. Classical simulations using the TIP4P/2005, TIP3P, TIP4P, TIP4P-Ew, simple point charge/extended, and TIP5P models are unable to reproduce the heat capacity of water. Given that classical simulations do not satisfy the third law of thermodynamics, one would expect such a failure at low temperatures. However, it seems that for water, nuclear quantum effects influence the heat capacities all the way up to room temperature. The failure of classical simulations to reproduce Cp points to the necessity of incorporating nuclear quantum effects to describe this property accurately.

  17. Effect of heat treatment on viability of Taenia hydatigena eggs.

    PubMed

    Buttar, Birpal S; Nelson, Mark L; Busboom, Jan R; Hancock, Dale D; Walsh, Douglas B; Jasmer, Douglas P

    2013-04-01

    Effects of heat treatments on activation and infectivity of Taenia hydatigena eggs were assessed. Eggs containing oncospheres were used for in vitro and in vivo studies to determine the response to 5min of heat treatment, ranging from room temperature (22°C) to 60°C. The study demonstrated 99.47% and 100% reduction in oncosphere activation or infectivity after 5min of heat treatment at 60°C and 57.38°C under in vitro and in vivo conditions, respectively. Similar results between the two approaches indicted the appropriateness of the in vitro methods to identify oncosphericidal treatments of practical significance. Similar heat treatments may also be effective against Taenia saginata and help to reduce occurrence of beef cysticercosis.

  18. The effects of water on heat-styling damage.

    PubMed

    Christian, Paul; Winsey, Nigel; Whatmough, Marie; Cornwell, Paul A

    2011-01-01

    Heated styling appliances, such as straightening irons, have grown in popularity in recent years, as have hair products such as heat-protection sprays. In this study we investigate whether the water in a heat-protection spray can affect the level of damage caused by heat styling. Tryptophan damage from heat styling was measured using fluorescence spectroscopy, and structural damage was investigated using light microscopy and single-fiber tensile testing. Hair samples were heat treated with straightening irons, following treatment with either a water-based, "wet," heat-protection spray or an ethanol-based, "dry," spray. Results showed that, as expected, tryptophan damage was reduced by repeated applications of both the "wet" and "dry" heat-protection sprays. However, no differences were seen between the "wet" versus the "dry" product. Light microscopy studies showed greater structural damage to hair treated with water and the "wet" spray. Tensile tests confirmed that there was greater damage to hair treated with the "wet" spray. Decreases in Young's modulus were greater in the presence of the "wet" spray. The results of this study suggest that the type of damage caused by heat treatments is different in wet versus dry hair. In dry hair, thermal treatments cause chemical damage and some structural damage. However, in wet hair, thermal treatments cause the same chemical damage, but considerably more structural damage, which causes significant changes in the physical properties of the hair. It is likely that the rapid evaporation of water from the hair is the main causal factor. Our experiments suggest that the effectiveness of commercial heat-protection sprays can be improved by the removal of water and by the use of volatile ingredients, such as ethanol, as base solvents. PMID:21443842

  19. The effects of water on heat-styling damage.

    PubMed

    Christian, Paul; Winsey, Nigel; Whatmough, Marie; Cornwell, Paul A

    2011-01-01

    Heated styling appliances, such as straightening irons, have grown in popularity in recent years, as have hair products such as heat-protection sprays. In this study we investigate whether the water in a heat-protection spray can affect the level of damage caused by heat styling. Tryptophan damage from heat styling was measured using fluorescence spectroscopy, and structural damage was investigated using light microscopy and single-fiber tensile testing. Hair samples were heat treated with straightening irons, following treatment with either a water-based, "wet," heat-protection spray or an ethanol-based, "dry," spray. Results showed that, as expected, tryptophan damage was reduced by repeated applications of both the "wet" and "dry" heat-protection sprays. However, no differences were seen between the "wet" versus the "dry" product. Light microscopy studies showed greater structural damage to hair treated with water and the "wet" spray. Tensile tests confirmed that there was greater damage to hair treated with the "wet" spray. Decreases in Young's modulus were greater in the presence of the "wet" spray. The results of this study suggest that the type of damage caused by heat treatments is different in wet versus dry hair. In dry hair, thermal treatments cause chemical damage and some structural damage. However, in wet hair, thermal treatments cause the same chemical damage, but considerably more structural damage, which causes significant changes in the physical properties of the hair. It is likely that the rapid evaporation of water from the hair is the main causal factor. Our experiments suggest that the effectiveness of commercial heat-protection sprays can be improved by the removal of water and by the use of volatile ingredients, such as ethanol, as base solvents.

  20. [A cold/heat property classification strategy based on bio-effects of herbal medicines].

    PubMed

    Jiang, Miao; Lv, Ai-Ping

    2014-06-01

    The property theory of Chinese herbal medicine (CHM) is regarded as the core and basic of Chinese medical theory, however, the underlying mechanism of the properties in CHMs remains unclear, which impedes a barrier for the modernization of Chinese herbal medicine. The properties of CHM are often categorized into cold and heat according to the theory of Chinese medicine, which are essential to guide the clinical application of CHMs. There is an urgent demand to build a cold/heat property classification model to facilitate the property theory of Chinese herbal medicine, as well as to clarify the controversial properties of some herbs. Based on previous studies on the cold/heat properties of CHM, in this paper, we described a novel strategy on building a cold/heat property classification model based on herbal bio-effect. The interdisciplinary cooperation of systems biology, pharmacological network, and pattern recognition technique might lighten the study on cold/heat property theory, provide a scientific model for determination the cold/heat property of herbal medicines, and a new strategy for expanding the Chinese herbal medicine resources as well. PMID:25272861

  1. Shock Heating: Effects on Chondritic Material

    NASA Technical Reports Server (NTRS)

    Desch, S. J.; Ciesla, F. J.; Hood, L. L.; Nakamoto, T.

    2004-01-01

    At the 1994 Conference on Chondrules and the Protoplanetary Disk, shock waves were discussed as mechanisms that may have been responsible for forming chondrules, millimeter-sized igneous spheres which are significant components of chondritic meteorites, and references therein]. At the time, shock waves were appealing because they were thought to be brief, repetitive events that were quantitatively shown to be able to rapidly heat silicates to the appropriate temperatures for chondrule formation. Since that meeting, more detailed models for the thermal processing of material in shock waves have been developed. These models have tracked the thermal evolution of the silicates for longer periods of time and found that their cooling rates are also consistent with what has been inferred for chondrules. In addition to the thermal histories of these particles, shock waves may be able to explain a number of other features observed in primitive meteorites. Here, we review the recent work that has been done in studying the interaction of solids with shock waves in the solar nebula.

  2. Current heating induced spin Seebeck effect

    SciTech Connect

    Schreier, Michael Roschewsky, Niklas; Dobler, Erich; Meyer, Sibylle; Huebl, Hans; Goennenwein, Sebastian T. B.; Gross, Rudolf

    2013-12-09

    A measurement technique for the spin Seebeck effect is presented, wherein the normal metal layer used for its detection is exploited simultaneously as a resistive heater and thermometer. We show how the various contributions to the measured total signal can be disentangled, allowing to extract the voltage signal solely caused by the spin Seebeck effect. To this end, we performed measurements as a function of the external magnetic field strength and its orientation. We find that the effect scales linearly with the induced rise in temperature, as expected for the spin Seebeck effect.

  3. Current heating induced spin Seebeck effect

    NASA Astrophysics Data System (ADS)

    Schreier, Michael; Roschewsky, Niklas; Dobler, Erich; Meyer, Sibylle; Huebl, Hans; Gross, Rudolf; Goennenwein, Sebastian T. B.

    2013-12-01

    A measurement technique for the spin Seebeck effect is presented, wherein the normal metal layer used for its detection is exploited simultaneously as a resistive heater and thermometer. We show how the various contributions to the measured total signal can be disentangled, allowing to extract the voltage signal solely caused by the spin Seebeck effect. To this end, we performed measurements as a function of the external magnetic field strength and its orientation. We find that the effect scales linearly with the induced rise in temperature, as expected for the spin Seebeck effect.

  4. Effects of deception in social networks

    PubMed Central

    Iñiguez, Gerardo; Govezensky, Tzipe; Dunbar, Robin; Kaski, Kimmo; Barrio, Rafael A.

    2014-01-01

    Honesty plays a crucial role in any situation where organisms exchange information or resources. Dishonesty can thus be expected to have damaging effects on social coherence if agents cannot trust the information or goods they receive. However, a distinction is often drawn between prosocial lies (‘white’ lies) and antisocial lying (i.e. deception for personal gain), with the former being considered much less destructive than the latter. We use an agent-based model to show that antisocial lying causes social networks to become increasingly fragmented. Antisocial dishonesty thus places strong constraints on the size and cohesion of social communities, providing a major hurdle that organisms have to overcome (e.g. by evolving counter-deception strategies) in order to evolve large, socially cohesive communities. In contrast, white lies can prove to be beneficial in smoothing the flow of interactions and facilitating a larger, more integrated network. Our results demonstrate that these group-level effects can arise as emergent properties of interactions at the dyadic level. The balance between prosocial and antisocial lies may set constraints on the structure of social networks, and hence the shape of society as a whole. PMID:25056625

  5. The effect of asymmetric heating on flow stability and heat transfer for flow in a vertical tube

    SciTech Connect

    Tappan, C.H.

    1987-11-01

    This study presents experimental results of combined free and forced convection heat transfer in a vertical tube with a circumferentially nonuniform constant wall heat flux. The effect of an asymmetric wall heat flux on flow stability and on the rate of heat transfer for water flowing downward in a vertical tube was investigated. Experimental results were used to develop two stability maps which identify various flow regimes, corresponding to different thermal and hydraulic conditions. Heat transfer coefficients were also determined. Experimental results in the present investigation were compared to those with uniform heating in horizontal and vertical tube flow situations discussed in the literature. 23 refs., 12 figs., 1 tab.

  6. Effects of polarization-charge shielding in microwave heating

    SciTech Connect

    Lin, M. S.; Lin, S. M.; Chiang, W. Y.; Barnett, L. R.; Chu, K. R.

    2015-08-15

    Heating of dielectric objects by radio frequency (RF) and microwaves has long been a method widely employed in scientific research and industrial applications. However, RF and microwave heating are often susceptible to an excessive temperature spread due to uneven energy deposition. The current study elucidates an important physical reason for this difficulty and proposes an effective remedy. Non-spherical samples are placed in an anechoic chamber, where it is irradiated by a traveling microwave wave with 99% intensity uniformity. Polarization charges induced on the samples tend to partially cancel the incident electric field and hence reduce the heating rate. The polarization-charge shielded heating rate is shown to be highly dependent on the sample's shape and its orientation relative to the wave electric field. For samples with a relatively high permittivity, the resultant uneven heating can become a major cause for the excessive temperature spread. It is also demonstrated that a circularly polarized wave, with its rapidly rotating electric field, can effectively even out the heating rate and hence the temperature spread.

  7. Effect of combined heat and radiation on microbial destruction.

    PubMed Central

    Fisher, D A; Pflug, I J

    1977-01-01

    A series of experiments at several levels of relative humidity and radiation dose rates was carried out using spores of Bacillus subtilis var. niger to evaluate the effect of heat alone, radiation alone, and a combination of heat and radiation. Combined heat and radiation treatment of microorganisms yields a destruction rate greater than the additive rates of the independence agents. The synergistic mechanism shows a proportional dependency on radiation dose rate an Arrhenius dependency on temperature, and a dependency on relative humidity. Maximum synergism occurs under conditions where heat and radiation individually destroy microorganisms at approximately equal rates. Larger synergistic advantage is possible at low relative humidities rather than at high relative humidities. PMID:406843

  8. Respiratory effects of wood heat: clinical observations and epidemiologic assessment.

    PubMed

    Honicky, R E; Osborne, J S

    1991-11-01

    An increasing number of families in the United States are converting to woodburning stoves in an effort to reduce winter heating bills. Woodburning stoves operate as a contained combuster of wood and produce a variety of pollutants as byproducts of combustion. Although technological advances have reduced emissions to some degree, even the most efficient woodburning stoves emit hazardous pollutants directly into the home when the stove is operating and the door is opened to add wood. The question arises as to whether pollutants are accumulating in homes where woodburning stoves are used as a source of heat. This issue is especially important considering the trend to increase home insulation and overall airtightness in an effort to conserve energy and reduce heat loss. This paper reviews the clinical case report that first postulated an association of recurrent chest illness with woodburning stove exposure and summarizes the findings to date on respiratory effects of wood heat for young children.

  9. Effects of network node consolidation in optical access and aggregation networks on costs and power consumption

    NASA Astrophysics Data System (ADS)

    Lange, Christoph; Hülsermann, Ralf; Kosiankowski, Dirk; Geilhardt, Frank; Gladisch, Andreas

    2010-01-01

    The increasing demand for higher bit rates in access networks requires fiber deployment closer to the subscriber resulting in fiber-to-the-home (FTTH) access networks. Besides higher access bit rates optical access network infrastructure and related technologies enable the network operator to establish larger service areas resulting in a simplified network structure with a lower number of network nodes. By changing the network structure network operators want to benefit from a changed network cost structure by decreasing in short and mid term the upfront investments for network equipment due to concentration effects as well as by reducing the energy costs due to a higher energy efficiency of large network sites housing a high amount of network equipment. In long term also savings in operational expenditures (OpEx) due to the closing of central office (CO) sites are expected. In this paper different architectures for optical access networks basing on state-of-the-art technology are analyzed with respect to network installation costs and power consumption in the context of access node consolidation. Network planning and dimensioning results are calculated for a realistic network scenario of Germany. All node consolidation scenarios are compared against a gigabit capable passive optical network (GPON) based FTTH access network operated from the conventional CO sites. The results show that a moderate reduction of the number of access nodes may be beneficial since in that case the capital expenditures (CapEx) do not rise extraordinarily and savings in OpEx related to the access nodes are expected. The total power consumption does not change significantly with decreasing number of access nodes but clustering effects enable a more energyefficient network operation and optimized power purchase order quantities leading to benefits in energy costs.

  10. Network effects of deep brain stimulation

    PubMed Central

    Alhourani, Ahmad; McDowell, Michael M.; Randazzo, Michael J.; Wozny, Thomas A.; Kondylis, Efstathios D.; Lipski, Witold J.; Beck, Sarah; Karp, Jordan F.; Ghuman, Avniel S.

    2015-01-01

    The ability to differentially alter specific brain functions via deep brain stimulation (DBS) represents a monumental advance in clinical neuroscience, as well as within medicine as a whole. Despite the efficacy of DBS in the treatment of movement disorders, for which it is often the gold-standard therapy when medical management becomes inadequate, the mechanisms through which DBS in various brain targets produces therapeutic effects is still not well understood. This limited knowledge is a barrier to improving efficacy and reducing side effects in clinical brain stimulation. A field of study related to assessing the network effects of DBS is gradually emerging that promises to reveal aspects of the underlying pathophysiology of various brain disorders and their response to DBS that will be critical to advancing the field. This review summarizes the nascent literature related to network effects of DBS measured by cerebral blood flow and metabolic imaging, functional imaging, and electrophysiology (scalp and intracranial electroencephalography and magnetoencephalography) in order to establish a framework for future studies. PMID:26269552

  11. Network effects of deep brain stimulation.

    PubMed

    Alhourani, Ahmad; McDowell, Michael M; Randazzo, Michael J; Wozny, Thomas A; Kondylis, Efstathios D; Lipski, Witold J; Beck, Sarah; Karp, Jordan F; Ghuman, Avniel S; Richardson, R Mark

    2015-10-01

    The ability to differentially alter specific brain functions via deep brain stimulation (DBS) represents a monumental advance in clinical neuroscience, as well as within medicine as a whole. Despite the efficacy of DBS in the treatment of movement disorders, for which it is often the gold-standard therapy when medical management becomes inadequate, the mechanisms through which DBS in various brain targets produces therapeutic effects is still not well understood. This limited knowledge is a barrier to improving efficacy and reducing side effects in clinical brain stimulation. A field of study related to assessing the network effects of DBS is gradually emerging that promises to reveal aspects of the underlying pathophysiology of various brain disorders and their response to DBS that will be critical to advancing the field. This review summarizes the nascent literature related to network effects of DBS measured by cerebral blood flow and metabolic imaging, functional imaging, and electrophysiology (scalp and intracranial electroencephalography and magnetoencephalography) in order to establish a framework for future studies.

  12. Equilibrium & Nonequilibrium Fluctuation Effects in Biopolymer Networks

    NASA Astrophysics Data System (ADS)

    Kachan, Devin Michael

    speculate that cells take advantage of this equilibrium effect by tuning near the transition point, where small changes in free cross-linker density will affect large structural rearrangements between free filament networks and networks of bundles. Cells are naturally found far from equilibrium, where the active influx of energy from ATP consumption controls the dynamics. Motor proteins actively generate forces within biopolymer networks, and one may ask how these differ from the random stresses characteristic of equilibrium fluctuations. Besides the trivial observation that the magnitude is independent of temperature, I find that the processive nature of the motors creates a temporally correlated, or colored, noise spectrum. I model the network with a nonlinear scalar elastic theory in the presence of active driving, and study the long distance and large scale properties of the system with renormalization group techniques. I find that there is a new critical point associated with diverging correlation time, and that the colored noise produces novel frequency dependence in the renormalized transport coefficients. Finally, I study marginally elastic solids which have vanishing shear modulus due to the presence of soft modes, modes with zero deformation cost. Although network coordination is a useful metric for determining the mechanical response of random spring networks in mechanical equilibrium, it is insufficient for describing networks under external stress. In particular, under-constrained networks which are fluid-like at zero load will dynamically stiffen at a critical strain, as observed in numerical simulations and experimentally in many biopolymer networks. Drawing upon analogies to the stress induced unjamming of emulsions, I develop a kinetic theory to explain the rigidity transition in spring and filament networks. Describing the dynamic evolution of non-affine deformation via a simple mechanistic picture, I recover the emergent nonlinear strain

  13. A neural network combined with a three-dimensional finite element method applied to optimize eddy current and temperature distributions of traveling wave induction heating system

    NASA Astrophysics Data System (ADS)

    Wang, Youhua; Wang, Junhua; Ho, S. L.; Pang, Lingling; Fu, W. N.

    2011-04-01

    In this paper, neural networks with a finite element method (FEM) were introduced to predict eddy current distributions on the continuously moving thin conducting strips in traveling wave induction heating (TWIH) equipments. A method that combines a neural network with a finite element method (FEM) is proposed to optimize eddy current distributions of TWIH heater. The trained network used for tested examples shows quite good accuracy of the prediction. The results have then been used with reference to a double-side TWIH in order to analyze the distributions of the magnetic field and eddy current intensity, which accelerates the iterative solution process for the nonlinear coupled electromagnetic matters. The FEM computation of temperature converged conspicuously faster using the prediction results as initial values than using the zero values, and the number of iterations is reduced dramatically. Simulation results demonstrate the effectiveness and characteristics of the proposed method.

  14. Study on Fuel Cell Network System Considering Reduction in Fuel Cell Capacity Using Load Leveling and Heat Release Loss

    NASA Astrophysics Data System (ADS)

    Obara, Shin'ya; Kudo, Kazuhiko

    Reduction in fuel cell capacity linked to a fuel cell network system is considered. When the power demand of the whole network is small, some of the electric power generated by the fuel cell is supplied to a water electrolysis device, and hydrogen and oxygen gases are generated. Both gases are compressed with each compressor and they are stored in cylinders. When the electric demand of the whole network is large, both gases are supplied to the network, and fuel cells are operated by these hydrogen and oxygen gases. Furthermore, an optimization plan is made to minimize the quantity of heat release of the hot water piping that connects each building. Such an energy network is analyzed assuming connection of individual houses, a hospital, a hotel, a convenience store, an office building, and a factory. Consequently, compared with the conventional system, a reduction of 46% of fuel cell capacity is expected.

  15. Comparative physiology and transcriptional networks underlying the heat shock response in Populus trichocarpa, Arabidopsis thaliana and Glycine max

    SciTech Connect

    Weston, David; Wullschleger, Stan D; Yang, Xiaohan; Karve, Abhijit A; Gunter, Lee E; Jawdy, Sara; Allen, Sara M

    2011-01-01

    The heat shock response continues to be layered with additional complexity as interactions and crosstalk among heat shock proteins (HSPs), the reactive oxygen network and hormonal signalling are discovered. However, comparative analyses exploring variation in each of these processes among species remain relatively unexplored. In controlled environment experiments, photosynthetic response curves were conducted from 22 to 42 C and indicated that temperature optimum of light-saturated photosynthesis was greater for Glycine max relative to Arabidopsis thaliana or Populus trichocarpa. Transcript profiles were taken at defined states along the temperature response curves, and inferred pathway analysis revealed species-specific variation in the abiotic stress and the minor carbohydrate raffinose/galactinol pathways. A weighted gene co-expression network approach was used to group individual genes into network modules linking biochemical measures of the antioxidant system to leaf-level photosynthesis among P. trichocarpa, G. max and A. thaliana. Network-enabled results revealed an expansion in the G. max HSP17 protein family and divergence in the regulation of the antioxidant and heat shock modules relative to P. trichocarpa and A. thaliana. These results indicate that although the heat shock response is highly conserved, there is considerable species-specific variation in its regulation.

  16. Release behavior of non-network proteins and its relationship to the structure of heat-induced soy protein gels.

    PubMed

    Wu, Chao; Hua, Yufei; Chen, Yeming; Kong, Xiangzhen; Zhang, Caimeng

    2015-04-29

    Heat-induced soy protein gels were prepared by heating protein solutions at 12%, 15% ,or 18% for 0.5, 1.0, or 2.0 h. The release of non-network proteins from gel slices was conducted in 10 mM pH 7.0 sodium phosphate buffer. SDS-PAGE and diagonal electrophoresis demonstrated that the released proteins consisted of undenatured AB subunits and denatured proteins including monomers of A polypeptides, disulfide bond linked dimers, trimers, and polymers of A polypeptides, and an unidentified 15 kDa protein. SEC-HPLC analysis of non-network proteins revealed three major protein peaks, with molecular weights of approximately 253.9, 44.8, and 9.7 kDa. The experimental data showed that the time-dependent release of the three fractions from soy protein gels fit Fick's second law. An increasing protein concentration or heating time resulted in a decrease in diffusion coefficients of non-network proteins. A power law expression was used to describe the relationship between non-network protein diffusion coefficient and molecular weight, for which the exponent (α) shifted to higher value with an increase in protein concentration or heating time, indicating that a more compact gel structure was formed.

  17. Effects of Solar Photovoltaic Panels on Roof Heat Transfer

    NASA Technical Reports Server (NTRS)

    Dominguez, A.; Klessl, J.; Samady, M.; Luvall, J. C.

    2010-01-01

    Building Heating, Ventilation and Air Conditioning (HVAC) is a major contributor to urban energy use. In single story buildings with large surface area such as warehouses most of the heat enters through the roof. A rooftop modification that has not been examined experimentally is solar photovoltaic (PV) arrays. In California alone, several GW in residential and commercial rooftop PV are approved or in the planning stages. With the PV solar conversion efficiency ranging from 5-20% and a typical installed PV solar reflectance of 16-27%, 53-79% of the solar energy heats the panel. Most of this heat is then either transferred to the atmosphere or the building underneath. Consequently solar PV has indirect effects on roof heat transfer. The effect of rooftop PV systems on the building roof and indoor energy balance as well as their economic impacts on building HVAC costs have not been investigated. Roof calculator models currently do not account for rooftop modifications such as PV arrays. In this study, we report extensive measurements of a building containing a flush mount and a tilted solar PV array as well as exposed reference roof. Exterior air and surface temperature, wind speed, and solar radiation were measured and thermal infrared (TIR) images of the interior ceiling were taken. We found that in daytime the ceiling surface temperature under the PV arrays was significantly cooler than under the exposed roof. The maximum difference of 2.5 C was observed at around 1800h, close to typical time of peak energy demand. Conversely at night, the ceiling temperature under the PV arrays was warmer, especially for the array mounted flat onto the roof. A one dimensional conductive heat flux model was used to calculate the temperature profile through the roof. The heat flux into the bottom layer was used as an estimate of the heat flux into the building. The mean daytime heat flux (1200-2000 PST) under the exposed roof in the model was 14.0 Watts per square meter larger than

  18. Topological effects of network structure on long-term social network dynamics in a wild mammal.

    PubMed

    Ilany, Amiyaal; Booms, Andrew S; Holekamp, Kay E

    2015-07-01

    Social structure influences ecological processes such as dispersal and invasion, and affects survival and reproductive success. Recent studies have used static snapshots of social networks, thus neglecting their temporal dynamics, and focused primarily on a limited number of variables that might be affecting social structure. Here, instead we modelled effects of multiple predictors of social network dynamics in the spotted hyena, using observational data collected during 20 years of continuous field research in Kenya. We tested the hypothesis that the current state of the social network affects its long-term dynamics. We employed stochastic agent-based models that allowed us to estimate the contribution of multiple factors to network changes. After controlling for environmental and individual effects, we found that network density and individual centrality affected network dynamics, but that social bond transitivity consistently had the strongest effects. Our results emphasise the significance of structural properties of networks in shaping social dynamics. PMID:25975663

  19. Topological effects of network structure on long-term social network dynamics in a wild mammal.

    PubMed

    Ilany, Amiyaal; Booms, Andrew S; Holekamp, Kay E

    2015-07-01

    Social structure influences ecological processes such as dispersal and invasion, and affects survival and reproductive success. Recent studies have used static snapshots of social networks, thus neglecting their temporal dynamics, and focused primarily on a limited number of variables that might be affecting social structure. Here, instead we modelled effects of multiple predictors of social network dynamics in the spotted hyena, using observational data collected during 20 years of continuous field research in Kenya. We tested the hypothesis that the current state of the social network affects its long-term dynamics. We employed stochastic agent-based models that allowed us to estimate the contribution of multiple factors to network changes. After controlling for environmental and individual effects, we found that network density and individual centrality affected network dynamics, but that social bond transitivity consistently had the strongest effects. Our results emphasise the significance of structural properties of networks in shaping social dynamics.

  20. Topological effects of network structure on long-term social network dynamics in a wild mammal

    PubMed Central

    Ilany, Amiyaal; Booms, Andrew S.; Holekamp, Kay E.

    2015-01-01

    Social structure influences ecological processes such as dispersal and invasion, and affects survival and reproductive success. Recent studies have used static snapshots of social networks, thus neglecting their temporal dynamics, and focused primarily on a limited number of variables that might be affecting social structure. Here, instead we modelled effects of multiple predictors of social network dynamics in the spotted hyena, using observational data collected during 20 years of continuous field research in Kenya. We tested the hypothesis that the current state of the social network affects its long-term dynamics. We employed stochastic agent-based models that allowed us to estimate the contribution of multiple factors to network changes. After controlling for environmental and individual effects, we found that network density and individual centrality affected network dynamics, but that social bond transitivity consistently had the strongest effects. Our results emphasise the significance of structural properties of networks in shaping social dynamics. PMID:25975663

  1. Effects of Freestream Turbulence on Turbine Blade Heat Transfer

    NASA Technical Reports Server (NTRS)

    Boyle, Robert J.; Giel, Paul W.; Ames, Forrest E.

    2004-01-01

    Experiments have shown that moderate turbulence levels can nearly double turbine blade stagnation region heat transfer. Data have also shown that heat transfer is strongly affected by the scale of turbulence as well as its level. In addition to the stagnation region, turbulence is often seen to increase pressure surface heat transfer. This is especially evident at low to moderate Reynolds numbers. Vane and rotor stagnation region, and vane pressure surface heat transfer augmentation is often seen in a pre-transition environment. Accurate predictions of transition and relaminarization are critical to accurately predicting blade surface heat transfer. An approach is described which incorporates the effects of both turbulence level and scale into a CFD analysis. The model is derived from experimental data for cylindrical and elliptical leadng edges. Results using this model are compared to experimental data for both vane and rotor geometries. The comparisons are made to illustrate that using a model which includes the effects of turbulence length scale improves agreement with data, and to illustrate where improvements in the modeling are needed.

  2. Causes, effects and molecular mechanisms of testicular heat stress.

    PubMed

    Durairajanayagam, Damayanthi; Agarwal, Ashok; Ong, Chloe

    2015-01-01

    The process of spermatogenesis is temperature-dependent and occurs optimally at temperatures slightly lower than that of the body. Adequate thermoregulation is imperative to maintain testicular temperatures at levels lower than that of the body core. Raised testicular temperature has a detrimental effect on mammalian spermatogenesis and the resultant spermatozoa. Therefore, thermoregulatory failure leading to heat stress can compromise sperm quality and increase the risk of infertility. In this paper, several different types of external and internal factors that may contribute towards testicular heat stress are reviewed. The effects of heat stress on the process of spermatogenesis, the resultant epididymal spermatozoa and on germ cells, and the consequent changes in the testis are elaborated upon. We also discuss the molecular response of germ cells to heat exposure and the possible mechanisms involved in heat-induced germ cell damage, including apoptosis, DNA damage and autophagy. Further, the intrinsic and extrinsic pathways that are involved in the intricate mechanism of germ cell apoptosis are explained. Ultimately, these complex mechanisms of apoptosis lead to germ cell death.

  3. Effect of Heat and Heat Acclimatization on Cycling Time Trial Performance and Pacing

    PubMed Central

    RACINAIS, SEBASTIEN; PÉRIARD, JULIEN D.; KARLSEN, ANDERS; NYBO, LARS

    2015-01-01

    ABSTRACT Purpose This study aimed to determine the effects of heat acclimatization on performance and pacing during outdoor cycling time trials (TT, 43.4 km) in the heat. Methods Nine cyclists performed three TT in hot ambient conditions (TTH, approximately 37°C) on the first (TTH-1), sixth (TTH-2), and 14th (TTH-3) days of training in the heat. Data were compared with the average of two TT in cool condition (approximately 8°C) performed before and after heat acclimatization (TTC). Results TTH-1 (77 ± 6 min) was slower (P = 0.001) than TTH-2 (69 ± 5 min), and both were slower (P < 0.01) than TTC and TTH-3 (66 ± 3 and 66 ± 4 min, respectively), without differences between TTC and TTH-3 (P > 0.05). The cyclists initiated the first 20% of all TT at a similar power output, irrespective of climate and acclimatization status; however, during TTH-1, they subsequently had a marked decrease in power output, which was partly attenuated after 6 d of acclimatization and was further reduced after 14 d. HR was higher during the first 20% of TTH-1 than that in the other TT (P < 0.05), but there were no differences between conditions from 30% onward. Final rectal temperature was similar in all TTH (40.2°C ± 0.4°C, P = 1.000) and higher than that in TTC (38.5°C ± 0.6°C, P < 0.001). Conclusions After 2 wk of acclimatization, trained cyclists are capable of completing a prolonged TT in a similar time in the heat compared with cool conditions, whereas in the unacclimatized state, they experienced a marked decrease in power output during the TTH. PMID:24977692

  4. Effective disinfection of rough rice using infrared radiation heating

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The objective of this study was to investigate the effect of infrared (IR) heating and tempering treatments on disinfection of Aspergillus flavus in freshly harvested rough rice and storage rice. Rice samples with initial moisture contents (IMCs) of 14.1 to 27.0% (wet basis) were infected with A. fl...

  5. Reparable, high-density microelectronic module provides effective heat sink

    NASA Technical Reports Server (NTRS)

    Carlson, K. J.; Maytone, F. F.

    1967-01-01

    Reparable modular system is used for packaging microelectronic flat packs and miniature discrete components. This three-dimensional compartmented structure incorporates etched phosphor bronze sheets and frames with etched wire conductors. It provides an effective heat sink for electric power dissipation in the absence of convective cooling means.

  6. Enhancing Extreme Heat Health-Related Intervention and Preparedness Activities Using Remote Sensing Analysis of Daily Surface Temperature, Surface Observation Networks and Ecmwf Reanalysis

    NASA Astrophysics Data System (ADS)

    Garcia, R. L.; Booth, J.; Hondula, D.; Ross, K. W.; Stuyvesant, A.; Alm, G.; Baghel, E.

    2015-12-01

    Extreme heat causes more human fatalities in the United States than any other natural disaster, elevating the concern of heat-related mortality. Maricopa County Arizona is known for its high heat index and its sprawling metropolitan complex which makes this region a perfect candidate for human health research. Individuals at higher risk are unequally spatially distributed, leaving the poor, homeless, non-native English speakers, elderly, and the socially isolated vulnerable to heat events. The Arizona Department of Health Services, Arizona State University and NASA DEVELOP LaRC are working to establish a more effective method of placing hydration and cooling centers in addition to enhancing the heat warning system to aid those with the highest exposure. Using NASA's Earth Observation Systems from Aqua and Terra satellites, the daily spatial variability within the UHI was quantified over the summer heat seasons from 2005 - 2014, effectively establishing a remotely sensed surface temperature climatology for the county. A series of One-way Analysis of Variance revealed significant differences between daily surface temperature averages of the top 30% of census tracts within the study period. Furthermore, synoptic upper tropospheric circulation patterns were classified to relate surface weather types and heat index. The surface weather observation networks were also reviewed for analyzing the veracity of the other methods. The results provide detailed information regarding nuances within the UHI effect and will allow pertinent recommendations regarding the health department's adaptive capacity. They also hold essential components for future policy decision-making regarding appropriate locations for cooling centers and efficient warning systems.

  7. Effects of heat losses (or gains) from insulated portions of closed-loop thermosyphons with vertical heat transfer sections

    NASA Astrophysics Data System (ADS)

    Bernier, M. A.; Baliga, B. R.

    1993-05-01

    The effect of heat losses or gains in the modeling of thermosyphons is investigated analytically using a closed-loop model where the circulating liquid is heated by a constant and uniform heat flux in the heated section of the loop and is cooled in a cooling section maintained at a constant wall temperature; elsewhere the pipes are insulated from the ambient fluid. The results of the analysis indicate that the performance of a closed-loop thermosyphon can be markedly affected by heat gains or losses in the insulated sections of the loop.

  8. Effects of passive heat stress on human somatosensory processing.

    PubMed

    Nakata, Hiroki; Oshiro, Misaki; Namba, Mari; Shibasaki, Manabu

    2015-12-01

    Herein, we investigated the effects of passive heat stress on human somatosensory processing recorded by somatosensory-evoked potentials (SEPs). Fifteen healthy subjects received a median nerve stimulation at the left wrist under two thermal conditions: Heat Stress and normothermic Time Control. The latencies and amplitudes of P14, N20, P25, N35, P45, and N60 at C4' and P14, N18, P22, and N30 at Fz were evaluated. Under the Heat Stress condition, SEPs were recorded at normothermic baseline (1st), early in heat stress (2nd), when esophageal temperature had increased by ~1.0°C (3rd) and ~2.0°C (4th), and after heat stress (5th). In the Time Control condition, SEPs were measured at the same time intervals as those in the Heat Stress condition. The peak latencies and amplitudes of SEPs did not change early in heat stress. However, the latencies of P14, N20, and N60 at C4' and P14, N18, and P22 at Fz were significantly shorter in the 4th session than in the 1st session. Furthermore, the peak amplitudes of P25 and N60 at C4', and P22 and N30 at Fz decreased with increases in body temperature. On the other hand, under the Time Control condition, no significant differences were observed in the amplitudes or latencies of any component of SEPs. These results suggested that the conduction velocity of the ascending somatosensory input was accelerated by increases in body temperature, and hyperthermia impaired the neural activity of cortical somatosensory processing. PMID:26468258

  9. Effect of heat loss on laminar flamelet species concentration

    NASA Astrophysics Data System (ADS)

    Boccanera, Marco; Lentini, Diego

    2016-10-01

    The effects of heat loss on the structure of laminar flamelets, which are the constitutive elements of turbulent flames under the most common operating conditions, are investigated for typical aeronautical gas-turbine operating conditions at take-off. The magnitude of heat loss is quantified via the "enthalpy defect" measured with respect to an adiabatic flame. A procedure to generate laminar flamelets with an assigned enthalpy defect at the boundaries is devised and applied to nonpremixed propane/air flames, as propane reproduces the essential features of higher hydrocarbon combustion. It is found, contrary to commonly held beliefs, that the enthalpy defect has a significant effect on the concentration not only of minor species, but also of main reaction products. Such effects are found in general to be more pronounced for fuel-rich conditions. An impact is anticipated on the formation rate of nitric oxides. The effects of scalar dissipation rate are also discussed.

  10. Synergistic Effects of Toxic Elements on Heat Shock Proteins

    PubMed Central

    Mahmood, Khalid; Mahmood, Qaisar; Irshad, Muhammad; Hussain, Jamshaid

    2014-01-01

    Heat shock proteins show remarkable variations in their expression levels under a variety of toxic conditions. A research span expanded over five decades has revealed their molecular characterization, gene regulation, expression patterns, vast similarity in diverse groups, and broad range of functional capabilities. Their functions include protection and tolerance against cytotoxic conditions through their molecular chaperoning activity, maintaining cytoskeleton stability, and assisting in cell signaling. However, their role as biomarkers for monitoring the environmental risk assessment is controversial due to a number of conflicting, validating, and nonvalidating reports. The current knowledge regarding the interpretation of HSPs expression levels has been discussed in the present review. The candidature of heat shock proteins as biomarkers of toxicity is thus far unreliable due to synergistic effects of toxicants and other environmental factors. The adoption of heat shock proteins as “suit of biomarkers in a set of organisms” requires further investigation. PMID:25136596

  11. Effect of re-heating on the hot electron temperature

    SciTech Connect

    Estabrook, K.; Rosen, M.

    1980-06-17

    Resonant absorption is the direct conversion of the transverse laser light to longitudinal electron plasma waves (epw) at the critical density (10/sup 21/ (1.06 ..mu..m/lambda/sub 0/)/sup 2/ cm/sup -3/). The oscillating longitudinal electric field of the epw heats the electrons by accelerating them down the density gradient to a temperature of approximately 21T/sub e//sup 0/ /sup 25/ ((I(W/cm/sup 2/)/10/sup 16/)(lambda/sub 0//1.06 ..mu..m)/sup 2/)/sup 0/ /sup 4/. This section extends the previous work by studying the effects of magnetic fields and collisions (albedo) which return the heated electrons for further heating. A magnetic field increases their temperature and collisions do not.

  12. Scale effects in the latent heat of melting in nanopores.

    PubMed

    Shin, J-H; Parlange, J-Y; Deinert, M R

    2013-07-28

    The curvature of a liquid vapor interface has long been known to change the equilibrium vapor pressure. It has also been shown that a capillary structure will affect the temperature at which both freezing and vaporization of a substance will occur. However, describing interfacial effects on the latent heat of a phase change has proven more difficult. Here, we present a classical thermodynamic model for how the latent heat of melting changes as the size of the particles undergoing the transition decreases. The scale dependence for the surface tension is taken into consideration using a Tolman length correction. The resulting model is tested by fitting to published experimental data for the latent heat of melting for benzene, heptane, naphthalene, and water contained in nano-porous glass. In all cases the model fits the data with a R(2) ≥ 0.94. PMID:23901997

  13. Effects of wake passing on stagnation region heat transfer

    NASA Technical Reports Server (NTRS)

    O'Brien, J. E.

    1988-01-01

    In the present experimental study, an annular-flow wind tunnel fitted with a spoked-wheel wake generator was used to ascertain both time-averaged and time-resolved effects of wake passing in a cylinder stagnation region; the cylindrical spokes generated wakes simulating those of a turbine inlet guide vanes. The time-averaged heat transfer results obtained indicate an asymmetric heat-transfer coefficient distribution about the stagnation line, with higher heat-transfer coefficients on the side corresponding to the suction side of the turbine blade. Spectra of the hot-film records indicate that vortex-shedding is a major contributor to the unsteady buffeting of the test-cylinder boundary layer at circumferential stations located at both + and -60 deg from the stagnation line, despite making only a minor contribution to the stagnation line itself.

  14. Effective Heat therapy Controlling Heat Deposition of Microbubbles in the Ultrasound Field

    NASA Astrophysics Data System (ADS)

    Kaneko, Yukio; Iida, Naoyuki; Matsumoto, Yoichiro

    2007-05-01

    It is required that the tumor site is coagulated less invasively and more efficiently, and HIFU treatment combined with microbubbles is investigated here. Microbubbles have a potential to enhance the heating effect in the ultrasound field. In this study, the relationship between the thermal effect and the behavior of microbubbles is analyzed. The temperature rise at the focal region was measured by a thermocouple, and the bubble behavior was simultaneously observed with a high-speed camera. The ultrasound frequency was 2.2 MHz and the intensity was 1000 - 5000 W/cm2. This time Levovist®, one of the contrast agents, was used as microbubbles, and the initial void fraction (the ratio of total gas volume to liquid) around the focal region was 0, 10-5, 10-4, 10-3 and 10-2%. The temperature rise became larger as the intensity of ultrasound and the void fraction increased. Comparing the data of the thermocouple with the photographs taken by the camera, the temperature rise became large as the bubbles were violently generated. When the ratio of heat energy to input acoustic energy for first 1 second irradiation is considered, the ratio mainly depends on the initial void fraction, and it becomes larger as the void fraction increases. On the other hand, when the ratio for 30 seconds is considered, it becomes smaller as the intensity of ultrasound increases. It is indicated that this is because resonance size of bubbles decrease during HIFU irradiation, for example, the microbubbles may break up or dissolve in water, or the bubbles grow too larger by the effect of rectified diffusion or coalescence. It is very important to consider the relationship between the thermal effect and the behavior of bubbles in the ultrasound field in order to control the heating effect of microbubbles and realize microbubble-enhanced HIFU treatment.

  15. Effect of heat treatment on stainless steel orthodontic wires.

    PubMed

    Cuoghi, Osmar Aparecido; Kasbergen, Geraldo Francisco; Santos, Paulo Henrique dos; Mendonça, Marcos Rogério de; Tondelli, Pedro Marcelo

    2011-01-01

    This study evaluated the effect of heat treatment on CrNi stainless steel orthodontic archwires. Half of forty archwires of each thickness - 0.014" (0.35 mm), 0.016" (0.40 mm), 0.018" (0.45 mm) and 0.020" (0.50 mm) (totalling 160 archwires) - were subjected to heat treatment while the remainder were not. All of the archwires had their individual thickness measured in the anterior and posterior regions using AutoCad 2000 software before and after compressive and tensile strength testing. The data was statistically analysed utilising multivariance ANOVA at a 5% significance level. All archwires without heat treatment that were subjected to tensile strength testing presented with anterior opening, which was more accentuated in the 0.020" archwires. In the posterior region, the opening produced by the tensile force was more accentuated in the archwires without heat treatment. There was greater stability in the thermally treated archwires, especially those subjected to tensile strength testing, which indicates that the heat treatment of orthodontic archwires establishes a favourable and indispensable condition to preserve the intercanine width. PMID:21359492

  16. Physiological effects of solar heat load in a fighter cockpit.

    PubMed

    Nunneley, S A; Myhre, L G

    1976-09-01

    The use of bubble canopies to improve vision in fighter aircraft exposes the cockpit to a high radiant heat load. Incoming sunlight increases the heat stress on crewmembers, both by raising air temperature and by directly heating exposed skin and clothing. An F-15 aircraft at Edwards AFB was modified to permit cockpit ventilation by external ground carts. Eight volunteers from the Test Pilot School were studied during 1-h periods in the closed cockpit, in sun and in shade. Mean cockpit air temperatures were 35.2 degrees C in shade and 51.9 degrees C in sun with PH2O less than 10 torr. The corresponding WBGT's were 22.6 and 36.4 degrees C. Sunlight added significantly to overall heat stress, as indicated by a rising heart rate and evaporative weight loss of 284 g/m2 - h (shade value was 109 g/m2 - hr). Mean skin temperatures were 34.3 degrees C in shade and 35.8 degrees C in sun. Particularly high skin temperatures were observed on the chest, the forehead and the top of the head under the helmet. The legs remained cool due to the flow of conditioned air, and this may explain why rectal temperature showed no meaningful change. Heat stress, which alone poses no physiological hazard, may cause crew performance decrements as well as diminishing acceleration tolerance. Possible means of eliminating or ameliorating these effects are discussed.

  17. Pressure Gradient Effects on Hypersonic Cavity Flow Heating

    NASA Technical Reports Server (NTRS)

    Everhart, Joel L.; Alter, Stephen J.; Merski, N. Ronald; Wood, William A.; Prabhu, Ramdas K.

    2007-01-01

    The effect of a pressure gradient on the local heating disturbance of rectangular cavities tested at hypersonic freestream conditions has been globally assessed using the two-color phosphor thermography method. These experiments were conducted in the Langley 31-Inch Mach 10 Tunnel and were initiated in support of the Space Shuttle Return-To-Flight Program. Two blunted-nose test surface geometries were developed, including an expansion plate test surface with nearly constant negative pressure gradient and a flat plate surface with nearly zero pressure gradient. The test surface designs and flow characterizations were performed using two-dimensional laminar computational methods, while the experimental boundary layer state conditions were inferred using the measured heating distributions. Three-dimensional computational predictions of the entire model geometry were used as a check on the design process. Both open-flow and closed-flow cavities were tested on each test surface. The cavity design parameters and the test condition matrix were established using the computational predictions. Preliminary conclusions based on an analysis of only the cavity centerline data indicate that the presence of the pressure gradient did not alter the open cavity heating for laminar-entry/laminar-exit flows, but did raise the average floor heating for closed cavities. The results of these risk-reduction studies will be used to formulate a heating assessment of potential damage scenarios occurring during future Space Shuttle flights.

  18. Pressure Gradient Effects on Hypersonic Cavity Flow Heating

    NASA Technical Reports Server (NTRS)

    Everhart, Joel L.; Alter, Stephen J.; Merski, N. Ronald; Wood, William A.; Prabhu, Ramadas K.

    2006-01-01

    The effect of a pressure gradient on the local heating disturbance of rectangular cavities tested at hypersonic freestream conditions has been globally assessed using the two-color phosphor thermography method. These experiments were conducted in the Langley 31-Inch Mach 10 Tunnel and were initiated in support of the Space Shuttle Return-To-Flight Program. Two blunted-nose test surface geometries were developed, including an expansion plate test surface with nearly constant negative pressure gradient and a flat plate surface with nearly zero pressure gradient. The test surface designs and flow characterizations were performed using two-dimensional laminar computational methods, while the experimental boundary layer state conditions were inferred using the measured heating distributions. Three-dimensional computational predictions of the entire model geometry were used as a check on the design process. Both open-flow and closed-flow cavities were tested on each test surface. The cavity design parameters and the test condition matrix were established using the computational predictions. Preliminary conclusions based on an analysis of only the cavity centerline data indicate that the presence of the pressure gradient did not alter the open cavity heating for laminar-entry/laminar-exit flows, but did raise the average floor heating for closed cavities. The results of these risk-reduction studies will be used to formulate a heating assessment of potential damage scenarios occurring during future Space Shuttle flights.

  19. Spectral effects on fast wave core heating and current drive

    NASA Astrophysics Data System (ADS)

    Phillips, C. K.; Bell, R. E.; Berry, L. A.; Bonoli, P. T.; Harvey, R. W.; Hosea, J. C.; Jaeger, E. F.; LeBlanc, B. P.; Ryan, P. M.; Taylor, G.; Valeo, E. J.; Wilgen, J. B.; Wilson, J. R.; Wright, J. C.; Yuh, H.; NSTX Team

    2009-07-01

    Recent results obtained with high harmonic fast wave (HHFW) heating and current drive (CD) on NSTX strongly support the hypothesis that the onset of perpendicular fast wave propagation right at or very near the launcher is a primary cause for a reduction in core heating efficiency at long wavelengths that is also observed in ICRF heating experiments in numerous tokamaks. A dramatic increase in core heating efficiency was first achieved in NSTX L-mode helium majority plasmas when the onset for perpendicular wave propagation was moved away from the antenna and nearby vessel structures. Efficient core heating in deuterium majority L-mode and H-mode discharges, in which the edge density is typically higher than in comparable helium majority plasmas, was then accomplished by reducing the edge density in front of the launcher with lithium conditioning and avoiding operational points prone to instabilities. These results indicate that careful tailoring of the edge density profiles in ITER should be considered to limit radio frequency (rf) power losses to the antenna and plasma facing materials. Finally, in plasmas with reduced rf power losses in the edge regions, the first direct measurements of HHFW CD were obtained with the motional Stark effect (MSE) diagnostic. The location and radial dependence of HHFW CD measured by MSE are in reasonable agreement with predictions from both full wave and ray tracing simulations.

  20. Spectral Effects on Fast Wave Core Heating and Current Drive

    SciTech Connect

    C.K. Phillips, R.E. Bell, L.A. Berry, P.T. Bonoli, R.W. Harvey, J.C. Hosea, E.F. Jaeger, B.P. LeBlanc, P.M. Ryan, G. Taylor, E.J. Valeo, J.R. Wilson, J.C. Wright, H. Yuh, and the NSTX Team

    2009-05-11

    Recent results obtained with high harmonic fast wave (HHFW) heating and current drive (CD) on NSTX strongly support the hypothesis that the onset of perpendicular fast wave propagation right at or very near the launcher is a primary cause for a reduction in core heating efficiency at long wavelengths that is also observed in ICRF heating experiments in numerous tokamaks. A dramatic increase in core heating efficiency was first achieved in NSTX L-mode helium majority plasmas when the onset for perpendicular wave propagation was moved away from the antenna and nearby vessel structures. Efficient core heating in deuterium majority L mode and H mode discharges, in which the edge density is typically higher than in comparable helium majority plasmas, was then accomplished by reducing the edge density in front of the launcher with lithium conditioning and avoiding operational points prone to instabilities. These results indicate that careful tailoring of the edge density profiles in ITER should be considered to limit rf power losses to the antenna and plasma facing materials. Finally, in plasmas with reduced rf power losses in the edge regions, the first direct measurements of high harmonic fast wave current drive were obtained with the motional Stark effect (MSE) diagnostic. The location and radial dependence of HHFW CD measured by MSE are in reasonable agreement with predictions from both full wave and ray tracing simulations.

  1. Electromagnetic heating effect of aggregated gold nanoparticle colloids

    NASA Astrophysics Data System (ADS)

    Liu, Xiaoming; Chen, Hui-jiuan; Chen, Xiaodong; Alfadhl, Yasir; Yu, Junsheng; Wen, Dongsheng

    2014-03-01

    Gold nanoparticles (GNPs) have been recently investigated intensively for potential hyperthermia treatment of malignant cancer cells in combination with radiofrequency (RF) electromagnetic (EM) fields/waves. However, many controversial results have been reported on whether GNPs can be heated by EM fields. It has been suggested that aggregated GNPs may be heated significantly by a RF field, which however has not been examined experimentally. This work proposes a novel electric treatment of mono-dispersed particles to create aggregated GNPs, and conducts an investigation of their bulk heating behavior under a 655 nm laser and a 13.56 MHz RF electric field. It is revealed that the heating rates of aggregated colloids are significantly higher than those of mono-dispersed GNPs for the 655 nm laser, whereas at 13.56 MHz, the heating effects are barely noticeable for both aggregated and mono-dispersed colloids. Various possible reasons are discussed and the negligible electric field enhancement is believed to be responsible at 13.56 MHz.

  2. Effective disinfection of rough rice using infrared radiation heating.

    PubMed

    Wang, Bei; Khir, Ragab; Pan, Zhongli; El-Mashad, Hamed; Atungulu, Griffiths G; Ma, Haile; McHugh, Tara H; Qu, Wenjuan; Wu, Bengang

    2014-09-01

    The objective of this study was to investigate the effect of infrared (IR) heating and tempering treatments on disinfection of Aspergillus flavus in freshly harvested rough rice and storage rice. Rice samples with initial moisture contents (IMCs) of 14.1 to 27.0% (wet basis) were infected with A. flavus spores before the tests. The infected samples were heated by IR radiation to 60°C in less than 1 min, and then samples were tempered at 60°C for 5, 10, 20, 30, 60, or 120 min. High heating rates and corresponding high levels of moisture removal were achieved using IR heating. The highest total moisture removal was 5.3% for the fresh rice with an IMC of 27.0% after IR heating and then 120 min of tempering. IR heating followed by tempering for 120 min resulted in 2.5- and 8.3-log reductions of A. flavus spores in rough rice with the lowest and highest IMCs, respectively. To study the effect on disinfection of rewetting dried storage rice, the surface of the dry rice was rewetted to achieve IMCs of 14.7 to 19.4% (wet basis). The rewetting process for the dry rice had a significant effect on disinfection. IR heating followed by tempering for 60 min resulted in 7.2-log reductions in A. flavus on rewetted rough rice. The log-linear plus tail model was applied to estimate the tempering time needed to achieve a 5-log reduction of A. flavus in rice of different IMCs. At least 30 and 20 min of tempering were needed for fresh rice and rewetted rice, respectively, with the highest IMCs. The recommended conditions of simultaneous disinfection and drying for fresh rice was IR heating to 60°C followed by tempering for 120 min and natural cooling, resulting in a final MC of 16.5 to 22.0%, depending on the IMC. For the rewetted dry rice with an IMC of 19.4%, the recommended condition for disinfection and drying involved only 20 min of tempering. The final MC of the sample was 13.8%, which is a safe MC for storage rice.

  3. Geothermal heating

    SciTech Connect

    Aureille, M.

    1982-01-01

    The aim of the study is to demonstrate the viability of geothermal heating projects in energy and economic terms and to provide nomograms from which an initial estimate may be made without having to use data-processing facilities. The effect of flow rate and temperature of the geothermal water on drilling and on the network, and the effect of climate on the type of housing are considered.

  4. Extraordinary induction heating effect near the first order Curie transition

    NASA Astrophysics Data System (ADS)

    Barati, M. R.; Selomulya, C.; Sandeman, K. G.; Suzuki, K.

    2014-10-01

    While materials with a 1st order Curie transition (TC) are known for the magnetic cooling effect due to the reversibility of their large entropy change, they also have a great potential as a candidate material for induction heating where a large loss power is required under a limited alternating magnetic field. We have carried out a proof-of-concept study on the induction heating effect in 1st order ferromagnetic materials where the temperature is self-regulated at TC. LaFe11.57Si1.43H1.75, a well-known magnetocaloric material, was employed in this study because TC of this compound (319 K) resides in the ideal temperature range for hyperthermia treatment of cancerous cells. It is found that the hysteresis loss of LaFe11.57Si1.43H1.75 increases dramatically near TC due to the magnetic phase coexistence associated with the 1st order magnetic transition. The spontaneous magnetization (Ms) shows a very abrupt decrease from 110 Am2kg-1 at 316 K to zero at 319 K. This large Ms immediately below TC along with the enhanced irreversibility of the hysteresis curve result in a specific absorption rate as large as 0.5 kWg-1 under a field of 8.8 kAm-1 at 279 kHz. This value is nearly an order of magnitude larger than that observed under the same condition for conventional iron oxide-based materials. Moreover, the large heating effect is self-regulated at the 1st order TC (319 K). This proof-of-concept study shows that the extraordinary heating effect near the 1st order Curie point opens up a novel alloy design strategy for large, self-regulated induction heating.

  5. Neural Network approach to assess the thermal affected zone around the injection well in a groundwater heat pump system

    NASA Astrophysics Data System (ADS)

    Lo Russo, Stefano; Taddia, Glenda; Verda, Vittorio

    2014-05-01

    The common use of well doublets for groundwater-sourced heating or cooling results in a thermal plume of colder or warmer re-injected groundwater known as the Thermal Affected Zone(TAZ). The plumes may be regarded either as a potential anthropogenic geothermal resource or as pollution, depending on downstream aquifer usage. A fundamental aspect in groundwater heat pump (GWHP) plant design is the correct evaluation of the thermally affected zone that develops around the injection well. Temperature anomalies are detected through numerical methods. Crucial elements in the process of thermal impact assessment are the sizes of installations, their position, the heating/cooling load of the building, and the temperature drop/increase imposed on the re-injected water flow. For multiple-well schemes, heterogeneous aquifers, or variable heating and cooling loads, numerical models that simulate groundwater and heat transport are needed. These tools should consider numerous scenarios obtained considering different heating/cooling loads, positions, and operating modes. Computational fluid dynamic (CFD) models are widely used in this field because they offer the opportunity to calculate the time evolution of the thermal plume produced by a heat pump, depending on the characteristics of the subsurface and the heat pump. Nevertheless, these models require large computational efforts, and therefore their use may be limited to a reasonable number of scenarios. Neural networks could represent an alternative to CFD for assessing the TAZ under different scenarios referring to a specific site. The use of neural networks is proposed to determine the time evolution of the groundwater temperature downstream of an installation as a function of the possible utilization profiles of the heat pump. The main advantage of neural network modeling is the possibility of evaluating a large number of scenarios in a very short time, which is very useful for the preliminary analysis of future multiple

  6. Duplication and Divergence Effect on Network Motifs in Undirected Bio-Molecular Networks.

    PubMed

    Pei Wang; Jinhu Lu; Xinghuo Yu; Zengrong Liu

    2015-06-01

    Duplication and divergence are two basic evolutionary mechanisms of bio-molecular networks. Real-world bio-molecular networks and their statistical characteristics can be well mimicked by artificial algorithms based on the two mechanisms. Bio-molecular networks consist of network motifs, which act as building blocks of large-scale networks. A fundamental question is how network motifs are evolved from long time evolution and natural selection. By considering the effect of various duplication and divergence strategies, we find that the underlying duplication scheme of the real-world undirected bio-molecular networks would rather follow the anti-preference strategy than the random one. The anti-preference duplication mechanism and the dimerization processes can lead to the formation of various motifs, and robustly conserve proper quantities of motifs in the artificial networks as that in the real-world ones. Furthermore, the anti-preference mechanism and edge deletion divergence can robustly preserve the sparsity of the networks. The investigations reveal the possible evolutionary mechanisms of network motifs in real-world bio-molecular networks, and have potential implications in the design, synthesis and reengineering of biological networks for biomedical purpose. PMID:25203993

  7. Upper Colorado River Basin Climate Effects Network

    USGS Publications Warehouse

    Belnap, Jayne; Campbell, Donald; Kershner, Jeff

    2011-01-01

    The Upper Colorado River Basin (UCRB) Climate Effects Network (CEN) is a science team established to provide information to assist land managers in future decision making processes by providing a better understanding of how future climate change, land use, invasive species, altered fire cycles, human systems, and the interactions among these factors will affect ecosystems and the services they provide to human communities. The goals of this group are to (1) identify science needs and provide tools to assist land managers in addressing these needs, (2) provide a Web site where users can access information pertinent to this region, and (3) provide managers technical assistance when needed. Answers to the team's working science questions are intended to address how interactions among climate change, land use, and management practices may affect key aspects of water availability, ecosystem changes, and societal needs within the UCRB.

  8. Effect of regional slope on drainage networks

    NASA Astrophysics Data System (ADS)

    Phillips, Loren F.; Schumm, S. A.

    1987-09-01

    Drainage networks that develop under conditions of no structural control and homogeneous lithology are generally dendritic, depending upon the shape and inclination of the surface on which they form. An experimental study was designed to investigate the effect of an increase of slope on the evolution and development of dendritic drainage patterns. As slope steepens, the pattern changes from dendritic at 1% slope, to subdendritic at 2%, to subparallel at 3%, to parallel at 5% and higher. The change from a dendritic-type pattern to a parallel-type pattern occurs at a low slope, between 2% and 3%, and primary channel junction angles decrease abruptly from about 60° to 43°. *Present address: U.S. Army Environmental Hygiene Agency, Attn: HSHB-ME-WM, Aberdeen Proving Ground, Maryland 21010-5422

  9. Self-Heating Effects In Polysilicon Source Gated Transistors

    PubMed Central

    Sporea, R. A.; Burridge, T.; Silva, S. R. P.

    2015-01-01

    Source-gated transistors (SGTs) are thin-film devices which rely on a potential barrier at the source to achieve high gain, tolerance to fabrication variability, and low series voltage drop, relevant to a multitude of energy-efficient, large-area, cost effective applications. The current through the reverse-biased source barrier has a potentially high positive temperature coefficient, which may lead to undesirable thermal runaway effects and even device failure through self-heating. Using numerical simulations we show that, even in highly thermally-confined scenarios and at high current levels, self-heating is insufficient to compromise device integrity. Performance is minimally affected through a modest increase in output conductance, which may limit the maximum attainable gain. Measurements on polysilicon devices confirm the simulated results, with even smaller penalties in performance, largely due to improved heat dissipation through metal contacts. We conclude that SGTs can be reliably used for high gain, power efficient analog and digital circuits without significant performance impact due to self-heating. This further demonstrates the robustness of SGTs. PMID:26351099

  10. Some effects of heat release in premixed flames

    SciTech Connect

    Shepherd, I.G.

    1994-03-01

    Numerical and experimental results are presented to illustrate some hydrodynamic effects of heat release in premixed flames. The heat release is represented by a simple model which treats the flame front as a two dimensional line source of volume. The velocity and strain rate induced in the flow field are determined and the numerical solution for the case of a laminar double kernel ignition is obtained. Of primary interest is the strain induced in the reactants between the expanding flame kernels and, for heat release rates typical of hydrocarbon flames, the strain rate at the plane of symmetry midway between the kernels up to 150 s{sup {minus}1}. The effects of kernel size, density ratio across the flame front and laminar burning velocity are studied. For the case of turbulent combustion the velocity induced in the reactant stream is measured in a plane parallel to the flame holder of an open premixed turbulent V-shaped flame. A divergent flow field, with a strain rate of 50 s{sup {minus}1}, is induced by the heat release in the flame zone and the consequences of this for determining the turbulent burning velocity in this and similar systems is reviewed.

  11. Effects of heat treatment parameters on liquid whole egg proteins.

    PubMed

    Uysal, Reyhan Selin; Boyacı, İsmail Hakkı; Soykut, Esra Acar; Ertaş, Nusret

    2017-02-01

    The aim of this study was to analyse the effect of heat treatment parameters on liquid whole egg (LWE) proteins by using ultraviolet-visible (UV-VIS) spectroscopy and capillary electrophoresis (CE). Heat treatment (at 60-68°C for 1-5min) was applied to LWE. Treated LWE was centrifuged and supernatant was taken for measurement of UV-VIS spectroscopy and CE. The change in UV absorbance showed loss of protein solubility depending on heat treatments parameters. Electropherograms of samples demonstrated the effect of treatment parameters on composition of LWE proteins. It was found that conalbumin and lysozyme were influenced by the treatment, while ovalbumin and ovomucoid were not affected. CE combined with principal component analysis (PCA) was used for classification of samples untreated or treated and treated at different treatment parameters. The results of the study revealed that the extent of heat treatment in LWE samples could be determined with PCA of the CE measurements. PMID:27596410

  12. Prediction of Relaminarization Effects on Turbine Blade Heat Transfer

    NASA Technical Reports Server (NTRS)

    Boyle, R. J.; Giel, P. W.

    2001-01-01

    An approach to predicting turbine blade heat transfer when turbulent flow relaminarizes due to strong favorable pressure gradients is described. Relaminarization is more likely to occur on the pressure side of a rotor blade. While stators also have strong favorable pressure gradients, the pressure surface is less likely to become turbulent at low to moderate Reynolds numbers. Accounting for the effects of relaminarization for blade heat transfer can substantially reduce the predicted rotor surface heat transfer. This in turn can lead to reduced rotor cooling requirements. Two-dimensional midspan Navier-Stokes analyses were done for each of eighteen test cases using eleven different turbulence models. Results showed that including relaminarization effects generally improved the agreement with experimental data. The results of this work indicate that relatively small changes in rotor shape can be utilized to extend the likelihood of relaminarization to high Reynolds numbers. Predictions showing how rotor blade heat transfer at a high Reynolds number can be reduced through relaminarization are given.

  13. Self-Heating Effects In Polysilicon Source Gated Transistors.

    PubMed

    Sporea, R A; Burridge, T; Silva, S R P

    2015-09-09

    Source-gated transistors (SGTs) are thin-film devices which rely on a potential barrier at the source to achieve high gain, tolerance to fabrication variability, and low series voltage drop, relevant to a multitude of energy-efficient, large-area, cost effective applications. The current through the reverse-biased source barrier has a potentially high positive temperature coefficient, which may lead to undesirable thermal runaway effects and even device failure through self-heating. Using numerical simulations we show that, even in highly thermally-confined scenarios and at high current levels, self-heating is insufficient to compromise device integrity. Performance is minimally affected through a modest increase in output conductance, which may limit the maximum attainable gain. Measurements on polysilicon devices confirm the simulated results, with even smaller penalties in performance, largely due to improved heat dissipation through metal contacts. We conclude that SGTs can be reliably used for high gain, power efficient analog and digital circuits without significant performance impact due to self-heating. This further demonstrates the robustness of SGTs.

  14. Heating rate effects in simulated liquid Al2O_3

    NASA Astrophysics Data System (ADS)

    van Hoang, Vo

    2006-01-01

    The heating rate effects in simulated liquid Al{2}O{3} have been investigated by Molecular Dynamics (MD) method. Simulations were done in the basic cube under periodic boundary conditions containing 3000 ions with Born-Mayer type pair potentials. The temperature of the system was increasing linearly in time from the zero temperature as T(t)=T0 +γ t, where γ is the heating rate. The heating rate dependence of density and enthalpy of the system was found. Calculations show that static properties of the system such as the coordination number distributions and bond-angle distributions slightly depend on γ . Structure of simulated amorphous Al{2}O{3} model with the real density at the ambient pressure is in good agreement with Lamparter's experimental data. The heating rate dependence of dynamics of the system has been studied through the diffusion constant, mean-squared atomic displacement and comparison of partial radial distribution functions (PRDFs) for 10% most mobile and immobile particles with the corresponding mean ones. Finally, the evolution of diffusion constant of Al and O particles and structure of the system upon heating for the smallest heating rate was studied and presented. And we find that the temperature dependence of self-diffusion constant in the high temperature region shows a crossover to one which can be described well by a power law, D∝ (T-Tc )^γ . The critical temperature Tc is about 3500 K and the exponent γ is close to 0.941 for Al and to 0.925 for O particles. The glass phase transition temperature Tg for the Al{2}O{3} system is at anywhere around 2000 K.

  15. Gene Networks in the Wild: Identifying Transcriptional Modules that Mediate Coral Resistance to Experimental Heat Stress.

    PubMed

    Rose, Noah H; Seneca, Francois O; Palumbi, Stephen R

    2015-12-28

    Organisms respond to environmental variation partly through changes in gene expression, which underlie both homeostatic and acclimatory responses to environmental stress. In some cases, so many genes change in expression in response to different influences that understanding expression patterns for all these individual genes becomes difficult. To reduce this problem, we use a systems genetics approach to show that variation in the expression of thousands of genes of reef-building corals can be explained as variation in the expression of a small number of coexpressed "modules." Modules were often enriched for specific cellular functions and varied predictably among individuals, experimental treatments, and physiological state. We describe two transcriptional modules for which expression levels immediately after heat stress predict bleaching a day later. One of these early "bleaching modules" is enriched for sequence-specific DNA-binding proteins, particularly E26 transformation-specific (ETS)-family transcription factors. The other module is enriched for extracellular matrix proteins. These classes of bleaching response genes are clear in the modular gene expression analysis we conduct but are much more difficult to discern in single gene analyses. Furthermore, the ETS-family module shows repeated differences in expression among coral colonies grown in the same common garden environment, suggesting a heritable genetic or epigenetic basis for these expression polymorphisms. This finding suggests that these corals harbor high levels of gene-network variation, which could facilitate rapid evolution in the face of environmental change.

  16. Gene Networks in the Wild: Identifying Transcriptional Modules that Mediate Coral Resistance to Experimental Heat Stress

    PubMed Central

    Rose, Noah H.; Seneca, Francois O.; Palumbi, Stephen R.

    2016-01-01

    Organisms respond to environmental variation partly through changes in gene expression, which underlie both homeostatic and acclimatory responses to environmental stress. In some cases, so many genes change in expression in response to different influences that understanding expression patterns for all these individual genes becomes difficult. To reduce this problem, we use a systems genetics approach to show that variation in the expression of thousands of genes of reef-building corals can be explained as variation in the expression of a small number of coexpressed “modules.” Modules were often enriched for specific cellular functions and varied predictably among individuals, experimental treatments, and physiological state. We describe two transcriptional modules for which expression levels immediately after heat stress predict bleaching a day later. One of these early “bleaching modules” is enriched for sequence-specific DNA-binding proteins, particularly E26 transformation-specific (ETS)-family transcription factors. The other module is enriched for extracellular matrix proteins. These classes of bleaching response genes are clear in the modular gene expression analysis we conduct but are much more difficult to discern in single gene analyses. Furthermore, the ETS-family module shows repeated differences in expression among coral colonies grown in the same common garden environment, suggesting a heritable genetic or epigenetic basis for these expression polymorphisms. This finding suggests that these corals harbor high levels of gene-network variation, which could facilitate rapid evolution in the face of environmental change. PMID:26710855

  17. Gene Networks in the Wild: Identifying Transcriptional Modules that Mediate Coral Resistance to Experimental Heat Stress.

    PubMed

    Rose, Noah H; Seneca, Francois O; Palumbi, Stephen R

    2016-01-01

    Organisms respond to environmental variation partly through changes in gene expression, which underlie both homeostatic and acclimatory responses to environmental stress. In some cases, so many genes change in expression in response to different influences that understanding expression patterns for all these individual genes becomes difficult. To reduce this problem, we use a systems genetics approach to show that variation in the expression of thousands of genes of reef-building corals can be explained as variation in the expression of a small number of coexpressed "modules." Modules were often enriched for specific cellular functions and varied predictably among individuals, experimental treatments, and physiological state. We describe two transcriptional modules for which expression levels immediately after heat stress predict bleaching a day later. One of these early "bleaching modules" is enriched for sequence-specific DNA-binding proteins, particularly E26 transformation-specific (ETS)-family transcription factors. The other module is enriched for extracellular matrix proteins. These classes of bleaching response genes are clear in the modular gene expression analysis we conduct but are much more difficult to discern in single gene analyses. Furthermore, the ETS-family module shows repeated differences in expression among coral colonies grown in the same common garden environment, suggesting a heritable genetic or epigenetic basis for these expression polymorphisms. This finding suggests that these corals harbor high levels of gene-network variation, which could facilitate rapid evolution in the face of environmental change. PMID:26710855

  18. Dynamical effects of vegetation on the 2003 summer heat waves

    NASA Astrophysics Data System (ADS)

    Stéfanon, M.

    2012-04-01

    Dynamical effects of vegetation on the 2003 summer heat waves Marc Stéfanon(1), Philippe Drobinski(1), Fabio D'Andrea(1), Nathalie de Noblet(2) (1) IPSL/LMD, France; (2) IPSL/LSCE, France The land surface model (LSM) in regional climate models (RCMs) plays a key role in energy and water exchanges between land and atmosphere. The vegetation can affect these exchanges through physical, biophysical and bio-geophysical mechanisms. It participates to evapo-transpiration process which determines the partitioning of net radiation between sensible and latent heat flux, through water evaporation from soil throughout the entire root system. For seasonal timescale leaf cover change induced leaf-area index (LAI) and albedo changes, impacting the Earth's radiative balance. In addition, atmospheric chemistry and carbon concentration has a direct effect on plant stomatal structure, the main exchange interface with the atmosphere. Therefore the surface energy balance is intimately linked to the carbon cycle and vegetation conditions and an accurate representation of the Earth's surface is required to improve the performance of RCMs. It is even more crucial for extreme events as heat waves and droughts which display highly nonlinear behaviour. If triggering of heat waves is determined by the large scale, local coupled processes over land can amplify or inhibit heat trough several feedback mechanism. One set of two simulation has been conducted with WRF, using different LSMs. They aim to study drought and vegetation effect on the dynamical and hydrological processes controlling the occurrence and life cycle of heat waves In the MORCE plateform, the dynamical global vegetation model (DGVM) ORCHIDEE is implemented in the atmospheric module WRF. ORCHIDEE is based on three different modules. The first module, called SECHIBA, describes the fast processes such as exchanges of energy and water between the atmosphere and the biosphere, and the soil water budget. The phenology and carbon

  19. Effects of topology on network evolution

    NASA Astrophysics Data System (ADS)

    Oikonomou, Panos; Cluzel, Philippe

    2006-08-01

    The ubiquity of scale-free topology in nature raises the question of whether this particular network design confers an evolutionary advantage. A series of studies has identified key principles controlling the growth and the dynamics of scale-free networks. Here, we use neuron-based networks of boolean components as a framework for modelling a large class of dynamical behaviours in both natural and artificial systems. Applying a training algorithm, we characterize how networks with distinct topologies evolve towards a pre-established target function through a process of random mutations and selection. We find that homogeneous random networks and scale-free networks exhibit drastically different evolutionary paths. Whereas homogeneous random networks accumulate neutral mutations and evolve by sparse punctuated steps, scale-free networks evolve rapidly and continuously. Remarkably, this latter property is robust to variations of the degree exponent. In contrast, homogeneous random networks require a specific tuning of their connectivity to optimize their ability to evolve. These results highlight an organizing principle that governs the evolution of complex networks and that can improve the design of engineered systems.

  20. Effects of slitted fins on the heat transfer and pressure drop characteristics of a compact heat exchanger

    SciTech Connect

    Kim, C.H.; Yun, J.Y.

    1996-12-31

    A compact heat exchanger which consists of air-cooled aluminum fins and copper tubes circulating refrigerant has been used in a cooling system for a long time. There are two key parameters to be seriously considered for a design of the heat exchanger and its performance improvement. These are the heat transfer rate and pressure drop coefficient which varies with the change of the tube size, its arrangement and the fin configuration. In here, a numerical study was carried to understand the effect of the fin configuration on the heat transfer and pressure drop of the heat exchanger. The diameter and the arrangement of tubes were fixed but three different types of the fin configuration were used to see its effect on the heat transfer capacity and the static pressure drop. The calculation results were compared with that of a flat plate fin. From the comparison, it was found that the slitted fins have higher pressure drop; however, they have higher heat transfer rate. It means that the simpler of the fin configuration, the lower pressure drop and heat transfer coefficients are obtained. It is mainly due to the discretisation of the thermal boundary layer on the fin surface to maximize the heat transfer to air. The slitted sides of fins act like obstacles in the airflow path. From the experimental result, it was found that the same trend in the variation of the heat transfer rate and the pressure drop with the change of the fin configuration was obtained.

  1. Pathway-Dependent Effectiveness of Network Algorithms for Gene Prioritization

    PubMed Central

    Shim, Jung Eun; Hwang, Sohyun; Lee, Insuk

    2015-01-01

    A network-based approach has proven useful for the identification of novel genes associated with complex phenotypes, including human diseases. Because network-based gene prioritization algorithms are based on propagating information of known phenotype-associated genes through networks, the pathway structure of each phenotype might significantly affect the effectiveness of algorithms. We systematically compared two popular network algorithms with distinct mechanisms – direct neighborhood which propagates information to only direct network neighbors, and network diffusion which diffuses information throughout the entire network – in prioritization of genes for worm and human phenotypes. Previous studies reported that network diffusion generally outperforms direct neighborhood for human diseases. Although prioritization power is generally measured for all ranked genes, only the top candidates are significant for subsequent functional analysis. We found that high prioritizing power of a network algorithm for all genes cannot guarantee successful prioritization of top ranked candidates for a given phenotype. Indeed, the majority of the phenotypes that were more efficiently prioritized by network diffusion showed higher prioritizing power for top candidates by direct neighborhood. We also found that connectivity among pathway genes for each phenotype largely determines which network algorithm is more effective, suggesting that the network algorithm used for each phenotype should be chosen with consideration of pathway gene connectivity. PMID:26091506

  2. The combined effects of wall longitudinal heat conduction and inlet fluid flow maldistribution in crossflow plate-fin heat exchangers

    NASA Astrophysics Data System (ADS)

    Ranganayakulu, Ch.; Seetharamu, K. N.

    An analysis of a crossflow plate-fin compact heat exchanger, accounting for the combined effect of two-dimensional longitudinal heat conduction through the exchanger wall and nonuniform inlet fluid flow distribution on both hot and cold fluid sides is carried out using a finite element method. Using the fluid flow maldistribution models, the exchanger effectiveness and its deterioration due to the combined effects of longitudinal heat conduction and flow nonuniformity are calculated for various design and operating conditions of the exchanger. It was found that the performance deteriorations are quite significant in some typical applications due to the combined effects of wall longitudinal heat conduction and inlet fluid flow nonuniformity on crossflow plate-fin heat exchanger.

  3. Impact of Heat Wave Definitions on the Added Effect of Heat Waves on Cardiovascular Mortality in Beijing, China

    PubMed Central

    Dong, Wentan; Zeng, Qiang; Ma, Yue; Li, Guoxing; Pan, Xiaochuan

    2016-01-01

    Heat waves are associated with increased mortality, however, few studies have examined the added effect of heat waves. Moreover, there is limited evidence for the influence of different heat wave definitions (HWs) on cardiovascular mortality in Beijing, the capital of China. The aim of this study was to find the best HW definitions for cardiovascular mortality, and we examined the effect modification by an individual characteristic on cardiovascular mortality in Beijing, a typical northern city in China. We applied a Poisson generalized additive approach to estimate the differences in cardiovascular mortality during heat waves (using 12 HWs) compared with non-heat-wave days in Beijing from 2006 to 2009. We also validated the model fit by checking the residuals to ensure that the autocorrelation was successfully removed. In addition, the effect modifications by individual characteristics were explored in different HWs. Our results showed that the associations between heat waves and cardiovascular mortality differed from different HWs. HWs using the 93th percentile of the daily average temperature (27.7 °C) and a duration ≥5 days had the greatest risk, with an increase of 18% (95% confidence interval (CI): 6%, 31%) in the overall population, 24% (95% CI: 10%, 39%) in an older group (ages ≥65 years), and 22% (95% CI: 3%, 44%) in a female group. The added effect of heat waves was apparent after 5 consecutive heat wave days for the overall population and the older group. Females and the elderly were at higher risk than males and younger subjects (ages <65 years). Our findings suggest that heat wave definitions play a significant role in the relationship between heat wave and cardiovascular mortality. Using a suitable definition may have implications for designing local heat early warning systems and protecting the susceptible populations during heat waves. PMID:27657103

  4. Effect of heat processing on selected grain amaranth physicochemical properties.

    PubMed

    Muyonga, John H; Andabati, Brian; Ssepuuya, Geoffrey

    2014-01-01

    Grain amaranth is a pseudocereal with unique agricultural, nutritional, and functional properties. This study was undertaken to determine the effect of different heat-processing methods on physicochemical and nutraceutical properties in two main grain amaranth species, of Amaranthus hypochondriacus L. and Amaranthus cruentus L. Grains were prepared by roasting and popping, milled and analyzed for changes in in vitro protein digestibility, gruel viscosity, pasting characteristics, antioxidant activity, flavonoids, and total phenolics. In vitro protein digestibility was determined using the pepsin-pancreatin enzyme system. Viscosity and pasting characteristics of samples were determined using a Brookfield Viscometer and a Rapid Visco Analyzer, respectively. The grain methanol extracts were analysed for phenolics using spectrophotometry while antioxidant activity was determined using the DPPH (2,2-diphenyl-1-picrylhydrazyl) method. Heat treatment led to a reduction in protein digestibility, the effect being higher in popped than in roasted samples. Viscosities for roasted grain amaranth gruels were significantly higher than those obtained from raw and popped grain amaranth gruels. The results for pasting properties were consistent with the results for viscosity. In both A. hypochondriacus L. and A. cruentus L., the order of the viscosity values was roasted>raw>popped. The viscosities were also generally lower for A. cruentus L. compared to A. hypochondriacus L. Raw samples for both A. hypochondriacus L. and A. cruentus L. did not significantly differ in total phenolic content (TPC), total flavonoid content (TFC), and total antioxidant activity values. Thermal processing led to an increase in TFC and antioxidant activity. However, TPC of heat-processed samples remained unchanged. From the results, it can be concluded that heat treatment enhances antioxidant activity of grain amaranth and causes rheological changes dependent on the nature of heat treatment.

  5. Effect of heat processing on selected grain amaranth physicochemical properties

    PubMed Central

    Muyonga, John H; Andabati, Brian; Ssepuuya, Geoffrey

    2014-01-01

    Grain amaranth is a pseudocereal with unique agricultural, nutritional, and functional properties. This study was undertaken to determine the effect of different heat-processing methods on physicochemical and nutraceutical properties in two main grain amaranth species, of Amaranthus hypochondriacus L. and Amaranthus cruentus L. Grains were prepared by roasting and popping, milled and analyzed for changes in in vitro protein digestibility, gruel viscosity, pasting characteristics, antioxidant activity, flavonoids, and total phenolics. In vitro protein digestibility was determined using the pepsin-pancreatin enzyme system. Viscosity and pasting characteristics of samples were determined using a Brookfield Viscometer and a Rapid Visco Analyzer, respectively. The grain methanol extracts were analysed for phenolics using spectrophotometry while antioxidant activity was determined using the DPPH (2,2-diphenyl-1-picrylhydrazyl) method. Heat treatment led to a reduction in protein digestibility, the effect being higher in popped than in roasted samples. Viscosities for roasted grain amaranth gruels were significantly higher than those obtained from raw and popped grain amaranth gruels. The results for pasting properties were consistent with the results for viscosity. In both A. hypochondriacus L. and A. cruentus L., the order of the viscosity values was roasted>raw>popped. The viscosities were also generally lower for A. cruentus L. compared to A. hypochondriacus L. Raw samples for both A. hypochondriacus L. and A. cruentus L. did not significantly differ in total phenolic content (TPC), total flavonoid content (TFC), and total antioxidant activity values. Thermal processing led to an increase in TFC and antioxidant activity. However, TPC of heat-processed samples remained unchanged. From the results, it can be concluded that heat treatment enhances antioxidant activity of grain amaranth and causes rheological changes dependent on the nature of heat treatment. PMID

  6. Assembly effect of groups in online social networks

    NASA Astrophysics Data System (ADS)

    Fan, W.; Yeung, K. H.; Wong, K. Y.

    2013-03-01

    Due to the popularity and growth of online social networks, security in these networks becomes a critical problem. Previous works have proved that a virus can spread effectively in social networks. In this paper, groups in social networks are studied. We notice that groups on social network services sites can assemble people with similar characteristics, which may promote virus propagation in these networks. After our analysis, it is found that the use of groups can shorten the distance among users, and hence it would cause faster virus spread. We propose a virus propagation model and simulate it in a group network to show the assembly effect of groups. Our result shows that even with only one random attack, a virus can still spread rapidly, and the direct contact among group members is the reason for fast spreading.

  7. Network-scale effect on synchronizability of fully coupled network with connection delay.

    PubMed

    Zheng, Y G; Wang, Z H

    2016-04-01

    Network-scale effect on synchronizability of fully coupled network with connection delay is investigated in this paper. The master stability function, which governs the stability of synchronization manifold, is first obtained by separating the synchronization manifold direction from other transverse directions. Then, by introducing a new time variable in the master stability function, it is shown the effect of connection delay can be weakened with the increase of network scale, and thus, in contrast to the situation without connection delay, large network scale is more positive to the synchronizability of fully coupled network with connection delay. Those findings are confirmed by the studies on two specific networks with nodes of typical nonlinear dynamical systems. PMID:27131482

  8. Effect of mechanical surface and heat treatments on erosion resistance

    NASA Technical Reports Server (NTRS)

    Salik, J.; Buckley, D. H.

    1981-01-01

    The effect of erosion by glass beads and crushed glass and by heat treatments on the erosional resistance of 6061 aluminum alloy and 1045 steel were studied. The aluminum alloy's erosion resistance was found to be insensitive to mechanical surface treatment applied before testing, and was determined to depend on the properties of the work-hardened surface layer; this was also demonstrated for aluminum alloy single crystals. The aluminum alloy heat treatments included annealing, solution, and precipitation. Solution was found to increase erosion resistance but precipitation had the opposite effect. Hardness showed no correlation with erosion resistance for either aluminum alloy steel. The steel tests showed that crushed glass provides an order of magnitude more erosion than glass beads.

  9. Effects of nonlocal heat transport on laser implosion

    SciTech Connect

    Mima, K.; Honda, M.; Miyamoto, S.; Kato, S.

    1996-05-01

    A numerical simulation code describing the spherically symmetric implosion hydrodynamics has been developed to investigate the nonlocal heat transport effects on stable high velocity implosion and fast ignition. In the implosion simulation code HIMICO, the Fokker Planck equation for electron transport is solved to describe the nonlocal effects. For high ablation pressure implosion with a pressure higher than 200 Mbar, the isentrope is found higher by a factor 2 in the nonlocal transport model than in the Spitzer Harm model. As for the fast ignition simulation, the neutron yield for the high density compression with 10 KJ laser increases to be 20 times by injecting an additional heating pulse of 10 KJ with 1 psec. {copyright} {ital 1996 American Institute of Physics.}

  10. 75 FR 26180 - Effects on Broadband Communications Networks of Damage To or Failure of Network Equipment or...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-05-11

    ... COMMISSION 47 CFR Chapter I Effects on Broadband Communications Networks of Damage To or Failure of Network... broadband communications networks and to explore potential measures to reduce network vulnerability to failures in network equipment or severe overload conditions, such as would occur in natural...

  11. Effect of Surface Roughness on Optical Heating of Metals

    NASA Astrophysics Data System (ADS)

    Auinger, M.; Ebbinghaus, P.; Blümich, A.; Erbe, A.

    2014-01-01

    Heating by absorption of light is a commonly used technique to ensure a fast temperature increase of metallic samples. The rate of heating when using optical heating depends critically on the absorption of light by a sample. Here, the reflection and scattering of light from UV to IR by surfaces with different roughness of iron-based alloy samples (Fe, 1 wt-% Cr) is investigated. A combination of ellipsometric and optical scattering measurements is used to derive a simplified parametrisation which can be used to obtain the absorption of light from random rough metal surfaces, as prepared through conventional grinding and polishing techniques. By modelling the ellipsometric data of the flattest sample, the pseudodielectric function of the base material is derived. Describing an increased roughness by a Maxwell-Garnett model does not yield a reflectivity which follows the experimentally observed sum of scattered and reflected intensities. Therefore, a simple approach is introduced, based on multiple reflections, where the number of reflections depends on the surface roughness. This approach describes the data well, and is subsequently used to estimate the fraction of absorbed energy. Using numerical modelling, the effect on the heating rate is investigated. A numerical example is analysed, which shows that slight changes in roughness may result in big differences of the energy input into a metallic sample, with consequences on the achieved temperatures. Though the model oversimplifies reality, it provides a physically intuitive approach to estimate trends.

  12. Size effects in long-term quasistatic heat transport.

    PubMed

    Panasyuk, George Y; Yerkes, Kirk L

    2013-06-01

    We consider finite-size effects on heat transfer between thermal reservoirs mediated by a quantum system, where the number of modes in each reservoir is finite. Our approach is based on the generalized quantum Langevin equation and the thermal reservoirs are described as ensembles of oscillators within the Drude-Ullersma model. A general expression for the heat current between the thermal reservoirs in the long-time quasistatic regime, when an observation time is of the order of Δ(-1) and Δ is the mode spacing constant of a thermal reservoir, is obtained. The resulting equations that govern the long-time relaxation for the mode temperatures and the average temperatures of the reservoirs are derived and approximate analytical solutions are found. The obtained time dependencies of the temperatures and the resulting heat current reveal peculiarities at t=2πm/Δ with non-negative integers m and the heat current vanishes nonmonotonically when t→∞. The validity of Fourier's law for a chain of finite-size macroscopic subsystems is considered. As is shown, for characteristic times of the order of Δ(-1) the temperatures of subsystems' modes deviate from each other and the validity of Fourier's law cannot be established. In a case when deviations of initial temperatures of the subsystems from their average value are small, t→∞ asymptotic values for the mode temperatures do not depend on a mode's number and are the same as if Fourier's law were valid for all times.

  13. Effect of heat processing on DNA quantification of meat species.

    PubMed

    Şakalar, Ergün; Abasiyanik, M Fatih; Bektik, Emre; Tayyrov, Annageldi

    2012-09-01

    In this study, real-time polymerase chain reaction (PCR) was used for identifying the effects of different temperatures and times of heat treatment on the DNA of meat products. For this purpose, beef, pork, and chicken were baked at 200 °C for 10, 20, 30, 40, 50 min, and for 30 min at 30, 60, 90, 120, 150, 180, 210 °C and also cooked by boiling at 99 °C for 10, 30, 60, 90, 120, 150, 180, 210, and 240 min. The DNA was then extracted from all samples after the heat treatment. Further, a region of 374, 290, and 183-bp of mitochondrial DNA of beef, pork, and chicken, respectively, was amplified by real-time PCR. It was found that baking and boiling of the beef, pork, and chicken resulted in decreases in the detectable copy numbers of specific genes, which varied with the heating time and degree. The results indicated that species determination and quantification using real-time PCR are affected by the temperature, duration of the heat treatment, and size of the DNA fragment to be amplified.

  14. Effects of a Ground Source Heat Pump in Discontinuous Permafrost

    NASA Astrophysics Data System (ADS)

    Peterson, R.; Garber-Slaght, R.; Daanen, R. P.

    2015-12-01

    A ground source heat pump (GSHP) was installed in a discontinuous permafrost region of Fairbanks Alaska in 2013 with the primary aim of determining the effect of different ground cover options on the long-term subterranean temperature regime. Three different surface treatments were applied to separate loops of the GSHP; grass, sand, and gravel, and temperature monitoring was established at several depths above and below the heat sink loops. The GSHP has been actively utilized to supplement the heat in a hydronic heating system of a neighboring 5000 ft2 research facility. The ground immediately surrounding the GSHP was not permafrost when initially installed. Numerical modeling simulations were used to predict the long-term ground temperature regime surrounding the GSHP loops, and results indicate that permafrost would begin to form after the first year. A pseudo-steady state temperature regime would establish in approximately 8 years with a yearly fluctuation of -14°C to -2°C. Simulations also indicate that permafrost could be prevented with a 15 W/m recharge during the summer, such as from a solar thermal system. The ground surface treatments have negligible effect on the ground temperature below 1 meter and therefore have no long-term effect on the active region the GSHP. Data collected from thermistors in the two years since installation indicate that permafrost has not yet been established, although the ground is now becoming seasonally frozen due to the GSHP energy removal. Yearly average temperatures are declining, and extrapolation indicates that permafrost will establish in future years. The GSHP coefficient of performance (COP) was initially 3.6 and is declining with the decreasing ground temperatures. Economic modeling indicates that the system may become uneconomical in future years, although volatile energy costs have a substantial effect of the prediction.

  15. Effect of heat flux on differential rotation in turbulent convection.

    PubMed

    Kleeorin, Nathan; Rogachevskii, Igor

    2006-04-01

    We studied the effect of the turbulent heat flux on the Reynolds stresses in a rotating turbulent convection. To this end we solved a coupled system of dynamical equations which includes the equations for the Reynolds stresses, the entropy fluctuations, and the turbulent heat flux. We used a spectral tau approximation in order to close the system of dynamical equations. We found that the ratio of the contributions to the Reynolds stresses caused by the turbulent heat flux and the anisotropic eddy viscosity is of the order of approximately 10(L rho/l0)2, where l0 is the maximum scale of turbulent motions and L rho is the fluid density variation scale. This effect is crucial for the formation of the differential rotation and should be taken into account in the theories of the differential rotation of the Sun, stars, and planets. In particular, we demonstrated that this effect may cause the differential rotation which is comparable with the typical solar differential rotation.

  16. The contribution of geology and groundwater studies to city-scale ground heat network strategies: A case study from Cardiff, UK

    NASA Astrophysics Data System (ADS)

    Boon, David; Farr, Gareth; Patton, Ashley; Kendall, Rhian; James, Laura; Abesser, Corinna; Busby, Jonathan; Schofield, David; White, Debbie; Gooddy, Daren; James, David; Williams, Bernie; Tucker, David; Knowles, Steve; Harcombe, Gareth

    2016-04-01

    The development of integrated heat network strategies involving exploitation of the shallow subsurface requires knowledge of ground conditions at the feasibility stage, and throughout the life of the system. We describe an approach to the assessment of ground constraints and energy opportunities in data-rich urban areas. Geological and hydrogeological investigations have formed a core component of the strategy development for sustainable thermal use of the subsurface in Cardiff, UK. We present findings from a 12 month project titled 'Ground Heat Network at a City Scale', which was co-funded by NERC/BGS and the UK Government through the InnovateUK Energy Catalyst grant in 2015-16. The project examined the technical feasibility of extracting low grade waste heat from a shallow gravel aquifer using a cluster of open loop ground source heat pumps. Heat demand mapping was carried out separately. The ground condition assessment approach involved the following steps: (1) city-wide baseline groundwater temperature mapping in 2014 with seasonal monitoring for at least 12 months prior to heat pump installation (Patton et al 2015); (2) desk top and field-based investigation of the aquifer system to determine groundwater levels, likely flow directions, sustainable pumping yields, water chemistry, and boundary conditions; (3) creation of a 3D geological framework model with physical property testing and model attribution; (4) use steps 1-3 to develop conceptual ground models and production of maps and GIS data layers to support scenario planning, and initial heat network concept designs; (5) heat flow modelling in FEFLOW software to analyse sustainability and predict potential thermal breakthrough in higher risk areas; (6) installation of a shallow open loop GSHP research observatory with real-time monitoring of groundwater bodies to provide data for heat flow model validation and feedback for system control. In conclusion, early ground condition modelling and subsurface

  17. Network cloning unfolds the effect of clustering on dynamical processes

    NASA Astrophysics Data System (ADS)

    Faqeeh, Ali; Melnik, Sergey; Gleeson, James P.

    2015-05-01

    We introduce network L -cloning, a technique for creating ensembles of random networks from any given real-world or artificial network. Each member of the ensemble is an L -cloned network constructed from L copies of the original network. The degree distribution of an L -cloned network and, more importantly, the degree-degree correlation between and beyond nearest neighbors are identical to those of the original network. The density of triangles in an L -cloned network, and hence its clustering coefficient, is reduced by a factor of L compared to those of the original network. Furthermore, the density of loops of any fixed length approaches zero for sufficiently large values of L . Other variants of L -cloning allow us to keep intact the short loops of certain lengths. As an application, we employ these network cloning methods to investigate the effect of short loops on dynamical processes running on networks and to inspect the accuracy of corresponding tree-based theories. We demonstrate that dynamics on L -cloned networks (with sufficiently large L ) are accurately described by the so-called adjacency tree-based theories, examples of which include the message passing technique, some pair approximation methods, and the belief propagation algorithm used respectively to study bond percolation, SI epidemics, and the Ising model.

  18. EFFECTS OF HEAT AND BROMOCHLOROACETIC ACID ON MALE REPRODUCTION IN HEAT SHOCK FACTOR-1 GENE KNOCKOUT MICE

    EPA Science Inventory

    Effects of heat and bromochloroacetic acid on male reproduction in heat shock factor-1 gene knockout mice.
    Luft JC1, IJ Benjamin2, JB Garges1 and DJ Dix1. 1Reproductive Toxicology Division, USEPA, RTP, NC, 27711 and 2Dept of Internal Medicine, Univ.of Texas Southwestern Med C...

  19. Protective effects of ectoine on heat-stressed Daphnia magna.

    PubMed

    Adam, Bownik; Zofia, Stępniewska; Tadeusz, Skowroński

    2014-12-01

    Ectoine (ECT) is an amino acid produced and accumulated by halophilic bacteria in stressful conditions in order to prevent the loss of water from the cell. There is a lack of knowledge on the effects of ECT in heat-stressed aquatic animals. The purpose of our study was to determine the influence of ECT on Daphnia magna subjected to heat stress with two temperature gradients: 1 and 0.1 °C/min in the range of 23-42 °C. Time to immobilisation, survival during recovery, swimming performance, heart rate, thoracic limb movement and the levels of heat shock protein 70 kDa 1A (HSP70 1A), catalase (CAT) and nitric oxide species (NOx) were determined in ECT-exposed and unexposed daphnids; we showed protective effects of ECT on Daphnia magna subjected to heat stress. Time to immobilisation of daphnids exposed to ECT was longer when compared to the unexposed animals. Also, survival rate during the recovery of daphnids previously treated with ECT was higher. ECT significantly attenuated a rapid increase of mean swimming velocity which was elevated in the unexposed daphnids. Moreover, we observed elevation of thoracic limb movement and modulation of heart rate in ECT-exposed animals. HSP70 1A and CAT levels were reduced in the presence of ECT. On the other hand, NOx level was slightly elevated in both ECT-treated and unexposed daphnids, however slightly higher NOx level was found in ECT-treated animals. We conclude that the exposure to ectoine has thermoprotective effects on Daphnia magna, however their mechanisms are not associated with the induction of HSP70 1A.

  20. Protective effects of ectoine on heat-stressed Daphnia magna.

    PubMed

    Adam, Bownik; Zofia, Stępniewska; Tadeusz, Skowroński

    2014-12-01

    Ectoine (ECT) is an amino acid produced and accumulated by halophilic bacteria in stressful conditions in order to prevent the loss of water from the cell. There is a lack of knowledge on the effects of ECT in heat-stressed aquatic animals. The purpose of our study was to determine the influence of ECT on Daphnia magna subjected to heat stress with two temperature gradients: 1 and 0.1 °C/min in the range of 23-42 °C. Time to immobilisation, survival during recovery, swimming performance, heart rate, thoracic limb movement and the levels of heat shock protein 70 kDa 1A (HSP70 1A), catalase (CAT) and nitric oxide species (NOx) were determined in ECT-exposed and unexposed daphnids; we showed protective effects of ECT on Daphnia magna subjected to heat stress. Time to immobilisation of daphnids exposed to ECT was longer when compared to the unexposed animals. Also, survival rate during the recovery of daphnids previously treated with ECT was higher. ECT significantly attenuated a rapid increase of mean swimming velocity which was elevated in the unexposed daphnids. Moreover, we observed elevation of thoracic limb movement and modulation of heart rate in ECT-exposed animals. HSP70 1A and CAT levels were reduced in the presence of ECT. On the other hand, NOx level was slightly elevated in both ECT-treated and unexposed daphnids, however slightly higher NOx level was found in ECT-treated animals. We conclude that the exposure to ectoine has thermoprotective effects on Daphnia magna, however their mechanisms are not associated with the induction of HSP70 1A. PMID:25223383

  1. Adverse effects of prohibiting narrow provider networks.

    PubMed

    Howard, David H

    2014-08-14

    Many insurers participating in the new insurance exchanges are controlling costs by offering plans with narrow provider networks. Proposed regulations would promote network adequacy, but a pro-provider stance may not be inherently pro-consumer or even pro-patient. PMID:25119604

  2. Enhancing Classroom Effectiveness through Social Networking Tools

    ERIC Educational Resources Information Center

    Kurthakoti, Raghu; Boostrom, Robert E., Jr.; Summey, John H.; Campbell, David A.

    2013-01-01

    To determine the usefulness of social networking Web sites such as Ning.com as a communication tool in marketing courses, a study was designed with special concern for social network use in comparison to Blackboard. Students from multiple marketing courses were surveyed. Assessments of Ning.com and Blackboard were performed both to understand how…

  3. Revealing effective classifiers through network comparison

    NASA Astrophysics Data System (ADS)

    Gallos, Lazaros K.; Fefferman, Nina H.

    2014-11-01

    The ability to compare complex systems can provide new insight into the fundamental nature of the processes captured, in ways that are otherwise inaccessible to observation. Here, we introduce the n-tangle method to directly compare two networks for structural similarity, based on the distribution of edge density in network subgraphs. We demonstrate that this method can efficiently introduce comparative analysis into network science and opens the road for many new applications. For example, we show how the construction of a “phylogenetic tree” across animal taxa according to their social structure can reveal commonalities in the behavioral ecology of the populations, or how students create similar networks according to the University size. Our method can be expanded to study many additional properties, such as network classification, changes during time evolution, convergence of growth models, and detection of structural changes during damage.

  4. The Effect of Social Network Diagrams on a Virtual Network of Practice: A Korean Case

    ERIC Educational Resources Information Center

    Jo, Il-Hyun

    2009-01-01

    This study investigates the effect of the presentation of social network diagrams on virtual team members' interaction behavior via e-mail. E-mail transaction data from 22 software developers in a Korean IT company was analyzed and depicted as diagrams by social network analysis (SNA), and presented to the members as an intervention. Results…

  5. Effect of plants on sunspace passive solar heating

    SciTech Connect

    Best, E.D.; McFarland, R.D.

    1985-01-01

    The effect of plants on sunspace thermal performance is investigated, based on experiments done in Los Alamos using two test rooms with attached sunspaces, which were essentially identical except for the presence of plants in one. Performance is related to plant transpiration, evaporation from the soil, condensation on the glazing and the absorbtance of solar energy by the lightweight leaves. Performance effects have been quantified by measurements of auxiliary heat consumption in the test rooms and analyzed by means of energy balance calculations. A method for estimating the transpiration rate is presented.

  6. Responding to the Effects of Extreme Heat: Baltimore City's Code Red Program.

    PubMed

    Martin, Jennifer L

    2016-01-01

    Heat response plans are becoming increasingly more common as US cities prepare for heat waves and other effects of climate change. Standard elements of heat response plans exist, but plans vary depending on geographic location and distribution of vulnerable populations. Because heat events vary over time and affect populations differently based on vulnerability, it is difficult to compare heat response plans and evaluate responses to heat events. This article provides an overview of the Baltimore City heat response plan, the Code Red program, and discusses the city's response to the 2012 Ohio Valley/Mid Atlantic Derecho, a complex heat event. Challenges with and strategies for evaluating the program are reviewed and shared.

  7. Joule Heating Effects on Electrokinetic Flow Instabilities in Ferrofluids

    NASA Astrophysics Data System (ADS)

    Brumme, Christian; Shaw, Ryan; Zhou, Yilong; Prabhakaran, Rama; Xuan, Xiangchun

    We have demonstrated in our earlier work that the application of a tangential electric field can draw fluid instabilities at the interface of a ferrofluid/water co-flow. These electrokinetic flow instabilities are produced primarily by the mismatch of electric conductivities of the two fluids. We demonstrate in this talk that the Joule heating induced fluid temperature rises and gradients can significantly suppress the electrokinetic flow instabilities. We also develop a two-dimensional depth-averaged numerical model to predict the fluid temperature, flow and concentration fields in the two-fluid system with the goal to understand the Joule heating effects on electric field-driven ferrofluid flow instabilities. This work was supported by the Honors and Creative Inquiry programs at Clemson University.

  8. A heating window effect imaging experiment and its analysis

    NASA Astrophysics Data System (ADS)

    Peng, Zhiyong; Wang, Xiangjun; Lu, Jin

    2013-09-01

    In high speed flight, the aero-optical effect greatly affects infrared imaging system. An experiment investigating heating window radiance was conducted based the fluid computational simulation results. The paper gave the facilities needed and the procedures for experiment performance. The experiment data was analyzed by means of target signature evaluation principle, target contrast, SNR, gray level correlation index and gradient correlation index was computed from 4-bars infrared image. The results showed that the image region of interest was greatly affected by the heating window radiation. And some pre-processing skills should be introduced before implementing the target recognition and tracking algorithms. It is meaningful for validating performance of infrared imaging system with non-cooling window and to development methods of suppressing the hot dome radiation to reduce the image degradation.

  9. The effects of air leaks on solar air heating systems

    NASA Technical Reports Server (NTRS)

    Elkin, R.; Cash, M.

    1979-01-01

    This paper presents the results of an investigation to determine the effects of leakages in collector and duct work on the system performance of a typical single-family residence solar air heating system. Positive (leakage out) and negative (leakage in) pressure systems were examined. Collector and duct leakage rates were varied from 10 to 30 percent of the system flow rate. Within the range of leakage rates investigated, solar contribution to heated space and domestic hot water loads was found to be reduced up to 30 percent from the no-leak system contribution with duct leakage equally divided between supply and return duct; with supply duct leakage greater than return leakage a reduction of up to 35 percent was noted. The negative pressure system exhibited a reduction in solar contribution somewhat larger than the positive pressure system for the same leakage rates.

  10. Effective contaminant detection networks in uncertain groundwater flow fields.

    PubMed

    Hudak, P F

    2001-01-01

    A mass transport simulation model tested seven contaminant detection-monitoring networks under a 40 degrees range of groundwater flow directions. Each monitoring network contained five wells located 40 m from a rectangular landfill. The 40-m distance (lag) was measured in different directions, depending upon the strategy used to design a particular monitoring network. Lagging the wells parallel to the central flow path was more effective than alternative design strategies. Other strategies allowed higher percentages of leaks to migrate between monitoring wells. Results of this study suggest that centrally lagged groundwater monitoring networks perform most effectively in uncertain groundwater-flow fields.

  11. Length Scale and Gravity Effects on Microgravity Boiling Heat Transfer

    NASA Technical Reports Server (NTRS)

    Kim, Jungho; McQuillen, John; Balombin, Joe

    2002-01-01

    Boiling is a complex phenomenon where hydrodynamics, heat transfer, mass transfer, and interfacial phenomena are tightly interwoven. An understanding of boiling and critical heat flux in microgravity environments is of importance to space based hardware and processes such as heat exchange, cryogenic fuel storage and transportation, electronic cooling, and material processing due to the large amounts of heat that can be removed with relatively little increase in temperature. Although research in this area has been performed in the past four decades, the mechanisms by which heat is removed from surfaces in microgravity are still unclear. In earth gravity, buoyancy is an important parameter that affects boiling heat transfer through the rate at which bubbles are removed from the surface. A simple model describing the bubble departure size based on a quasistatic force balance between buoyancy and surface tension is given by the Fritz [I] relation: Bo(exp 1/2) = 0.0208 theta where Bo is the ratio between buoyancy and surface tension forces. For small, rapidly growing bubbles, inertia associated with the induced liquid motion can also cause bubble departure. In microgravity, the magnitude of effects related to natural convection and buoyancy are small and physical mechanisms normally masked by natural convection in earth gravity such as Marangoni convection can substantially influence the boiling and vapor bubble dynamics. CHF (critical heat transfer) is also substantially affected by microgravity. In 1 g environments, Bo has been used as a correlating parameter for CHF. Zuber's CHF model for an infinite horizontal surface assumes that vapor columns formed by the merger of bubbles become unstable due to a Helmholtz instability blocking the supply of liquid to the surface. The jets are spaced lambda(sub D) apart, where lambda(sub D) = 2pi square root of 3[(sigma)/(g(rho(sub l) - rho(sub v)](exp 1/2) = 2pi square root of 3 L Bo(exp -1/2) = square root of 3 lambda(sub c

  12. The effect of external boundary conditions on condensation heat transfer in rotating heat pipes

    NASA Technical Reports Server (NTRS)

    Daniels, T. C.; Williams, R. J.

    1979-01-01

    Experimental evidence shows the importance of external boundary conditions on the overall performance of a rotating heat pipe condenser. Data are presented for the boundary conditions of constant heat flux and constant wall temperature for rotating heat pipes containing either pure vapor or a mixture of vapor and noncondensable gas as working fluid.

  13. Leading edge film cooling effects on turbine blade heat transfer

    NASA Technical Reports Server (NTRS)

    Garg, Vijay K.; Gaugler, Raymond E.

    1995-01-01

    An existing three dimensional Navier-Stokes code, modified to include film cooling considerations, has been used to study the effect of spanwise pitch of shower-head holes and coolant to mainstream mass flow ratio on the adiabatic effectiveness and heat transfer coefficient on a film-cooled turbine vane. The mainstream is akin to that under real engine conditions with stagnation temperature = 1900 K and stagnation pressure = 3 MPa. It is found that with the coolant to mainstream mass flow ratio fixed, reducing P, the spanwise pitch for shower-head holes, from 7.5 d to 3.0 d, where d is the hole diameter, increases the average effectiveness considerably over the blade surface. However, when P/d= 7.5, increasing the coolant mass flow increases the effectiveness on the pressure surface but reduces it on the suction surface due to coolant jet lift-off. For P/d = 4.5 or 3.0, such an anomaly does not occur within the range of coolant to mainstream mass flow ratios analyzed. In all cases, adiabatic effectiveness and heat transfer coefficient are highly three-dimensional.

  14. Milk protein-gum tragacanth mixed gels: effect of heat-treatment sequence.

    PubMed

    Hatami, Masoud; Nejatian, Mohammad; Mohammadifar, Mohammad Amin; Pourmand, Hanieh

    2014-01-30

    The aim of this study was to investigate the role of the heat-treatment sequence of biopolymer mixtures as a formulation parameter on the acid-induced gelation of tri-polymeric systems composed of sodium caseinate (Na-caseinate), whey protein concentrate (WPC), and gum tragacanth (GT). This was studied by applying four sequences of heat treatment: (A) co-heating all three biopolymers; (B) heating the milk-protein dispersion and the GT dispersion separately; (C) heating the dispersion containing Na-caseinate and GT together and heating whey protein alone; and (D) co-heating whey protein with GT and heating Na-caseinate alone. According to small-deformation rheological measurements, the strength of the mixed-gel network decreased in the order: C>B>D>A samples. SEM micrographs show that the network of sample C is much more homogenous, coarse and dense than sample A, while the networks of samples B and D are of intermediate density. The heat-treatment sequence of the biopolymer mixtures as a formulation parameter thus offers an opportunity to control the microstructure and rheological properties of mixed gels.

  15. Effective centrality and explosive synchronization in complex networks

    NASA Astrophysics Data System (ADS)

    Navas, A.; Villacorta-Atienza, J. A.; Leyva, I.; Almendral, J. A.; Sendiña-Nadal, I.; Boccaletti, S.

    2015-12-01

    Synchronization of networked oscillators is known to depend fundamentally on the interplay between the dynamics of the graph's units and the microscopic arrangement of the network's structure. We here propose an effective network whose topological properties reflect the interplay between the topology and dynamics of the original network. On that basis, we are able to introduce the effective centrality, a measure that quantifies the role and importance of each network's node in the synchronization process. In particular, in the context of explosive synchronization, we use such a measure to assess the propensity of a graph to sustain an irreversible transition to synchronization. We furthermore discuss a strategy to induce the explosive behavior in a generic network, by acting only upon a fraction of its nodes.

  16. The effect of heat waves on dairy cow mortality.

    PubMed

    Vitali, A; Felici, A; Esposito, S; Bernabucci, U; Bertocchi, L; Maresca, C; Nardone, A; Lacetera, N

    2015-07-01

    This study investigated the mortality of dairy cows during heat waves. Mortality data (46,610 cases) referred to dairy cows older than 24mo that died on a farm from all causes from May 1 to September 30 during a 6-yr period (2002-2007). Weather data were obtained from 12 weather stations located in different areas of Italy. Heat waves were defined for each weather station as a period of at least 3 consecutive days, from May 1 to September 30 (2002-2007), when the daily maximum temperature exceeded the 90th percentile of the reference distribution (1971-2000). Summer days were classified as days in heat wave (HW) or not in heat wave (nHW). Days in HW were numbered to evaluate the relationship between mortality and length of the wave. Finally, the first 3 nHW days after the end of a heat wave were also considered to account for potential prolonged effects. The mortality risk was evaluated using a case-crossover design. A conditional logistic regression model was used to calculate odds ratio and 95% confidence interval for mortality recorded in HW compared with that recorded in nHW days pooled and stratified by duration of exposure, age of cows, and month of occurrence. Dairy cows mortality was greater during HW compared with nHW days. Furthermore, compared with nHW days, the risk of mortality continued to be higher during the 3 d after the end of HW. Mortality increased with the length of the HW. Considering deaths stratified by age, cows up to 28mo were not affected by HW, whereas all the other age categories of older cows (29-60, 61-96, and >96mo) showed a greater mortality when exposed to HW. The risk of death during HW was higher in early summer months. In particular, the highest risk of mortality was observed during June HW. Present results strongly support the implementation of adaptation strategies which may limit heat stress-related impairment of animal welfare and economic losses in dairy cow farm during HW.

  17. Effective Protocols for Mobile Communications and Networking

    SciTech Connect

    Espinoza, J.; Sholander, P.; Van Leeuwen, B,

    1998-12-01

    This report examines methods of mobile communications with an emphasis on mobile computing and wireless communications. Many of the advances in communications involve the use of Internet Protocol (IP), Asynchronous Transfer Mode (ATM), and ad hoc network protocols. However, many of the advances in these protocols have been focused on wired communications. Recently much focus has been directed at advancing communication technology in the area of mobile wireless networks. This report discusses various protocols used in mobile communications and proposes a number of extensions to existing protocols. A detailed discussion is also included on desirable protocol characteristics and evaluation criteria. In addition, the report includes a discussion on several network simulation tools that maybe used to evaluate network protocols.

  18. Effectiveness of exercise-heat acclimation for preventing heat illness in the workplace.

    PubMed

    Yamazaki, Fumio

    2013-09-01

    The incidence of heat-related illness in the workplace is linked to whether or not workers have acclimated to a hot environment. Heat acclimation improves endurance work performance in the heat and thermal comfort at a given work rate. These improvements are achieved by increased sweating and skin blood flow responses, better fluid balance and cardiovascular stability. As a practical means of acclimatizing the body to heat stress, daily aerobic exercise training is recommended since thermoregulatory capacity and blood volume increase with physical fitness. In workers wearing personal protective suits in hot environments, however, little psychophysiological benefit is received from short-term exercise training and/or heat acclimation because of the ineffectiveness of sweating for heat dissipation and the aggravation of thermal discomfort with the accumulation of sweat within the suit. For a manual laborer who works under uncompensable heat stress, better management of the work rate, the work environment and health is required.

  19. Effect of mechanical surface and heat treatments on erosion resistance

    NASA Technical Reports Server (NTRS)

    Salik, J.; Buckley, D. H.

    1980-01-01

    The effects of mechanical surface treatments as well as heat treatments on the erosion resistance of 6061 aluminum alloy and 1045 steel were studied. Mechanical surface treatments were found to have little or no effect on the erosion resistance. This is due to the formation by particle impact of a work hardened surface layer regardless of the initial surface condition. The erosion resistance of Al single crystals is found to be independent of orientation. This is due to destruction of the surface microstructure and formation of a polycrystalline surface layer by the impact of erodant particles as observed by X-ray diffraction. While upon solution treatment of annealed 6061 aluminum the increase in hardness is accompanied by an increase in erosion resistance, precipitation treatment which causes a further increase in hardness results in slightly lower erosion resistance. Using two types of erodant particles, glass beads and crushed glass, the erosion rate is found to be strongly dependent on erodant particle shape, being an order of magnitude higher for erosion with crushed glass as compared to glass beads. While for erosion with glass beads heat treatment of 1045 steel had a profound effect on its erosion resistance, little or no such effect was observed for erosion with crushed glass.

  20. Optimal artificial neural network architecture selection for performance prediction of compact heat exchanger with the EBaLM-OTR technique

    SciTech Connect

    Dumidu Wijayasekara; Milos Manic; Piyush Sabharwall; Vivek Utgikar

    2011-07-01

    Artificial Neural Networks (ANN) have been used in the past to predict the performance of printed circuit heat exchangers (PCHE) with satisfactory accuracy. Typically published literature has focused on optimizing ANN using a training dataset to train the network and a testing dataset to evaluate it. Although this may produce outputs that agree with experimental results, there is a risk of over-training or overlearning the network rather than generalizing it, which should be the ultimate goal. An over-trained network is able to produce good results with the training dataset but fails when new datasets with subtle changes are introduced. In this paper we present EBaLM-OTR (error back propagation and Levenberg-Marquardt algorithms for over training resilience) technique, which is based on a previously discussed method of selecting neural network architecture that uses a separate validation set to evaluate different network architectures based on mean square error (MSE), and standard deviation of MSE. The method uses k-fold cross validation. Therefore in order to select the optimal architecture for the problem, the dataset is divided into three parts which are used to train, validate and test each network architecture. Then each architecture is evaluated according to their generalization capability and capability to conform to original data. The method proved to be a comprehensive tool in identifying the weaknesses and advantages of different network architectures. The method also highlighted the fact that the architecture with the lowest training error is not always the most generalized and therefore not the optimal. Using the method the testing error achieved was in the order of magnitude of within 10{sup -5} - 10{sup -3}. It was also show that the absolute error achieved by EBaLM-OTR was an order of magnitude better than the lowest error achieved by EBaLM-THP.

  1. Microwave heating effect on rheology and microstructure of white sauces.

    PubMed

    Guardeño, Luis M; Sanz, Teresa; Fiszman, Susana M; Quiles, Amparo; Hernando, Isabel

    2011-10-01

    The microstructure and rheological properties of white sauces formulated with different starches were analyzed after being microwave-heated for different times. Significant differences (P < 0.05) in rheological parameters analyzed-storage modulus (G'), loss modulus (G″), and loss tangent (tanδ)-were obtained for sauces made with different starches. Microwave reheating did not affect G' and G″ values until water evaporation became significant. In addition, tanδ values did not change significantly (P < 0.05) even during long reheating times showing that sauce viscoelastic properties did not change after microwave irradiation. However, microstructure assessed by confocal laser scanning microscopy showed changes in fat globule and protein. These microstructural changes did not seem to have a significant effect on rheological measurements since starch and ι-carrageenan are mainly responsible for the viscoelastic behavior of the sauces. Practical Application:  The development of products appropriate to microwave heating is constantly rising in food industry. It is necessary to understand the behavior of the ingredients and the final product to microwave heating in order to choose those ingredients which will develop the best performance. Starches are common ingredients in industrial sauces, and rheological and microstructural techniques have shown their usefulness in characterization of starch-based systems. PMID:21913921

  2. Microwave heating effect on rheology and microstructure of white sauces.

    PubMed

    Guardeño, Luis M; Sanz, Teresa; Fiszman, Susana M; Quiles, Amparo; Hernando, Isabel

    2011-10-01

    The microstructure and rheological properties of white sauces formulated with different starches were analyzed after being microwave-heated for different times. Significant differences (P < 0.05) in rheological parameters analyzed-storage modulus (G'), loss modulus (G″), and loss tangent (tanδ)-were obtained for sauces made with different starches. Microwave reheating did not affect G' and G″ values until water evaporation became significant. In addition, tanδ values did not change significantly (P < 0.05) even during long reheating times showing that sauce viscoelastic properties did not change after microwave irradiation. However, microstructure assessed by confocal laser scanning microscopy showed changes in fat globule and protein. These microstructural changes did not seem to have a significant effect on rheological measurements since starch and ι-carrageenan are mainly responsible for the viscoelastic behavior of the sauces. Practical Application:  The development of products appropriate to microwave heating is constantly rising in food industry. It is necessary to understand the behavior of the ingredients and the final product to microwave heating in order to choose those ingredients which will develop the best performance. Starches are common ingredients in industrial sauces, and rheological and microstructural techniques have shown their usefulness in characterization of starch-based systems.

  3. The footprint of urban heat island effect in China

    PubMed Central

    Zhou, Decheng; Zhao, Shuqing; Zhang, Liangxia; Sun, Ge; Liu, Yongqiang

    2015-01-01

    Urban heat island (UHI) is one major anthropogenic modification to the Earth system that transcends its physical boundary. Using MODIS data from 2003 to 2012, we showed that the UHI effect decayed exponentially toward rural areas for majority of the 32 Chinese cities. We found an obvious urban/rural temperature “cliff”, and estimated that the footprint of UHI effect (FP, including urban area) was 2.3 and 3.9 times of urban size for the day and night, respectively, with large spatiotemporal heterogeneities. We further revealed that ignoring the FP may underestimate the UHI intensity in most cases and even alter the direction of UHI estimates for few cities. Our results provide new insights to the characteristics of UHI effect and emphasize the necessity of considering city- and time-specific FP when assessing the urbanization effects on local climate. PMID:26060039

  4. Effect of Preweld Heat Treatment on the Microstructure of Heat-Affected Zone (HAZ) and Weldability of Inconel 939 Superalloy

    NASA Astrophysics Data System (ADS)

    González Albarrán, M. A.; Martínez, D. I.; Díaz, E.; Díaz, J. C.; Guzman, I.; Saucedo, E.; Guzman, A. Ma.

    2014-04-01

    The effect of two preweld heat treatments on the final microstructure of a heat-affected zone (HAZ) and its effect on the weldability of the superalloy Inconel 939 have been analyzed. The HAZ cracking related to the mechanical driving force criteria during the cooling cycle was directly influenced by the strain state at this zone. Heat treatments result in the formation of (1) irregular γ' precipitates (more negative misfits) which showed higher strain (high density of interfacial dislocations) and (2) spherical precipitates (near-zero misfits) which as a result of their structure improve weldability by reducing weld HAZ cracking considerably.

  5. Urban effects on extreme heat in a mid-sized North American city

    NASA Astrophysics Data System (ADS)

    Schatz, J.; Kucharik, C. J.

    2013-12-01

    As climate change drives global temperatures higher, heat waves are projected to increase in frequency, intensity, and duration, particularly in cities where the urban heat island effect can further raise local temperatures. Cities contain 50% of the global population and 80% of the North American population, and these percentages are projected to reach 70% globally and 87% in North America by 2030. This creates a need to understand the nature of heat events not just globally but also within cities where local climate variation can be substantial. That local variation could prove highly consequential for heat adaptation in cities, making it important to understand the dynamics of extreme heat within urban landscapes. Our study addresses this need by characterizing 400m-resolution variation in air temperature and heat index during a historically hot year in Madison, Wisconsin. Madison is a mid-sized temperate city with a metropolitan area population of 568,593. It is surrounded by several large lakes and a complex rural landscape of agriculture, forests, wetlands, and grasslands. In 2012, Madison experienced its hottest year and third hottest summer on record, with the Madison airport reporting 39 days exceeding 90°F compared to an average of 9 days. In March 2012, we installed 135 Onset HOBO ProV2 T/RH sensors across the Madison area to record air temperature and relative humidity at 15 minute intervals. The data from this network provides a unique opportunity to study small-scale spatial variation in the magnitude and duration of hot conditions that are projected to become more common in the future. Our sensors recorded substantial variation in the magnitude and duration of high temperatures and heat indices during the summer of 2012. For temperature, the densest parts of the city experienced >200 hours ≥90°F compared to <100 hours in many rural areas. Temperatures ≥100°F occurred up to 22 hours in some parts of the city versus 0 hours in much of the rural

  6. Thermal and hydrodynamic behavior in flow networks

    SciTech Connect

    Yang, Wen-jei; Zhang, Nengli; Umeda, S. Fukuyama Univ. )

    1993-12-01

    It has been shown in earlier studies that a ramming of mutually intersecting flows results in a significant increase in convective heat transfer performance. Flow networks can therefore serve as effective heat transfer devices with potential applications in industry. Here, the mechanics of fluid flow and heat transfer in flow networks is explained in detail by combining results from previous investigations. 6 refs.

  7. Electrically heated tube investigation of cooling channel geometry effects

    NASA Technical Reports Server (NTRS)

    Meyer, Michael L.

    1995-01-01

    The results of an experimental investigation on the combined effects of cooling channel aspect ratio and curvature for rocket engines are presented. Symmetrically heated tubes with average heat fluxes up to 1.7 MW/m(exp 2) were used. The coolant was gaseous nitrogen at an inlet temperature of 280 K (500 R) and inlet pressures up to 1.0 x 10(exp 7) N/m(exp 2) (1500 psia). Two different tube geometries were tested: a straight, circular cross-section tube, and an aspect-ratio 10 cross-section tube with a 45 deg bend. The circular tube results are compared to classical models from the literature as validation of the system. The curvature effect data from the curved aspect-ratio 10 tube compare favorably to the empirical equations available in the literature for low aspect ratio tubes. This latter results suggest that thermal stratification of the coolant due to diminished curvature effect mixing may not be an issue for high aspect-ratio cooling channels.

  8. Nonequilibrium ionization effects in asymmetrically heated loops. [in solar corona

    NASA Technical Reports Server (NTRS)

    Spadaro, D.; Antiochos, Spiro K.; Mariska, J. T.

    1991-01-01

    The effects of nonequilibrium ionization on magnetic loop models with a steady siphon flow that is driven by a nonuniform heating rate are investigated. The model developed by Mariska (1988) to explain the observed redshifts of transition region emission lines is examined, and the number densities of the ions of carbon and oxygen along the loop are computed, with and without the approximation of ionization equilibrium. Considerable deviations from equilibrium were found. In order to determine the consequences of these nonequilibrium effects on the characteristics of the EUV emission from the loop plasma, the profiles and wavelength positions of all the important emission lines due to carbon and oxygen were calculated. The calculations are in broad agreement with Mariska's conclusions, although they show a significant diminution of the Doppler shifts, as well as modifications to the line widths. It is concluded that the inclusion of nonequilibrium effects make it more difficult to reproduce the observed characteristics of the solar transition region by means of the asymmetric-heating models.

  9. Monitoring the Surface Heat Island (shi) Effects of Industrial Enterprises

    NASA Astrophysics Data System (ADS)

    Şekertekin, A.; Kutoglu, Ş. H.; Kaya, S.; Marangoz, A. M.

    2016-06-01

    The aim of this study is to present the effects of industrial enterprises on Land Surface Temperature (LST) and to retrieve Surface Heat Island (SHI) maps of these regions. SHI is one of the types of Urban Heat Island (UHI) and as the urban areas grow in a city, UHI effect becomes bigger. The city centre of Zonguldak was chosen as study area and Landsat 5 satellite data were used as materials. Zonguldak has important industrial enterprises like thermal power plants and iron and steel plant. ERDEMIR is the biggest iron and steel plant in Turkey and it is one of the biggest ones in Europe, as well. There are three operating thermal power plants in the region namely CATES, ZETES1 and ZETES2. In order to investigate these industrial regions, Landsat 5 satellite data were processed using mono-window algorithm to retrieve LST and they were acquired on 11.09.1987, 18.09.2007 and 29.09.2011, respectively. The obtained results revealed that from 1987 to 2011, spatial and temporal variability in LST in industrial enterprises became higher than the surroundings. Besides, the sizes of SHIs in 2011 are bigger than the ones in 1987. For the countries and governments, having industrial enterprises is crucial for the development and it is also important to present the community better conditions in life. Thus, decision makers should consider mitigating the effects of these regions on LST.

  10. Effect of thymol in heating and recovery media on the isothermal and non-isothermal heat resistance of Bacillus spores.

    PubMed

    Esteban, Maria-Dolores; Conesa, Raquel; Huertas, Juan-Pablo; Palop, Alfredo

    2015-06-01

    Members of the genus Bacillus include important food-borne pathogen and spoilage microorganisms for food industry. Essential oils are natural products extracted from herbs and spices, which can be used as natural preservatives in many foods because of their antibacterial, antifungal, antioxidant and anti-carcinogenic properties. The aim of this research was to explore the effect of the addition of different concentrations of thymol to the heating and recovery media on the thermal resistance of spores of Bacillus cereus, Bacillus licheniformis and Bacillus subtilis at different temperatures. While the heat resistance was hardly reduced when thymol was present in the heating medium, the effect in the recovery medium was greater, reducing the D100 °C values down to one third for B. subtilis and B. cereus when 0.5 mM thymol was added. This effect was dose dependent and was also observed at other heating temperatures. PMID:25790989

  11. Effect of thymol in heating and recovery media on the isothermal and non-isothermal heat resistance of Bacillus spores.

    PubMed

    Esteban, Maria-Dolores; Conesa, Raquel; Huertas, Juan-Pablo; Palop, Alfredo

    2015-06-01

    Members of the genus Bacillus include important food-borne pathogen and spoilage microorganisms for food industry. Essential oils are natural products extracted from herbs and spices, which can be used as natural preservatives in many foods because of their antibacterial, antifungal, antioxidant and anti-carcinogenic properties. The aim of this research was to explore the effect of the addition of different concentrations of thymol to the heating and recovery media on the thermal resistance of spores of Bacillus cereus, Bacillus licheniformis and Bacillus subtilis at different temperatures. While the heat resistance was hardly reduced when thymol was present in the heating medium, the effect in the recovery medium was greater, reducing the D100 °C values down to one third for B. subtilis and B. cereus when 0.5 mM thymol was added. This effect was dose dependent and was also observed at other heating temperatures.

  12. Power to Detect Intervention Effects on Ensembles of Social Networks

    ERIC Educational Resources Information Center

    Sweet, Tracy M.; Junker, Brian W.

    2016-01-01

    The hierarchical network model (HNM) is a framework introduced by Sweet, Thomas, and Junker for modeling interventions and other covariate effects on ensembles of social networks, such as what would be found in randomized controlled trials in education research. In this article, we develop calculations for the power to detect an intervention…

  13. Effect of methylprednisolone on mammalian neuronal networks in vitro.

    PubMed

    Wittstock, Matthias; Rommer, Paulus S; Schiffmann, Florian; Jügelt, Konstantin; Stüwe, Simone; Benecke, Reiner; Schiffmann, Dietmar; Zettl, Uwe K

    2015-01-01

    Glucocorticosteroids (GCS) are widely used for the treatment of neurological diseases, e.g. multiple sclerosis. High levels of GCS are toxic to the central nervous system and can produce adverse effects. The effect of methylprednisolone (MP) on mammalian neuronal networks was studied in vitro. We demonstrate a dose-dependent excitatory effect of MP on cultured neuronal networks, followed by a shut-down of electrical activity using the microelectrode array technique.

  14. Generation of mirage effect by heated carbon nanotube thin film

    NASA Astrophysics Data System (ADS)

    Tong, L. H.; Lim, C. W.; Li, Y. C.; Zhang, Chuanzeng; Quoc Bui, Tinh

    2014-06-01

    Mirage effect, a common phenomenon in nature, is a naturally occurring optical phenomenon in which lights are bent due to the gradient variation of refraction in the temperature gradient medium. The theoretical analysis of mirage effect generated by heated carbon nanotube thin film is presented both for gas and liquid. Excellent agreement is demonstrated through comparing the theoretical prediction with published experimental results. It is concluded from the theoretical prediction and experimental observation that the mirage effect is more likely to happen in liquid. The phase of deflected optical beam is also discussed and the method for measurement of thermal diffusivity of medium is theoretically verified. Furthermore, a method for measuring the refractive index of gas by detecting optical beam deflection is also presented in this paper.

  15. Generation of mirage effect by heated carbon nanotube thin film

    SciTech Connect

    Tong, L. H.; Lim, C. W.; Li, Y. C.; Zhang, Chuanzeng; Quoc Bui, Tinh

    2014-06-28

    Mirage effect, a common phenomenon in nature, is a naturally occurring optical phenomenon in which lights are bent due to the gradient variation of refraction in the temperature gradient medium. The theoretical analysis of mirage effect generated by heated carbon nanotube thin film is presented both for gas and liquid. Excellent agreement is demonstrated through comparing the theoretical prediction with published experimental results. It is concluded from the theoretical prediction and experimental observation that the mirage effect is more likely to happen in liquid. The phase of deflected optical beam is also discussed and the method for measurement of thermal diffusivity of medium is theoretically verified. Furthermore, a method for measuring the refractive index of gas by detecting optical beam deflection is also presented in this paper.

  16. Heat shock proteins: in vivo heat treatments reveal adipose tissue depot-specific effects.

    PubMed

    Rogers, Robert S; Beaudoin, Marie-Soleil; Wheatley, Joshua L; Wright, David C; Geiger, Paige C

    2015-01-01

    Heat treatments (HT) and the induction of heat shock proteins (HSPs) improve whole body and skeletal muscle insulin sensitivity while decreasing white adipose tissue (WAT) mass. However, HSPs in WAT have been understudied. The purpose of the present study was to examine patterns of HSP expression in WAT depots, and to examine the effects of a single in vivo HT on WAT metabolism. Male Wistar rats received HT (41°C, 20 min) or sham treatment (37°C), and 24 h later subcutaneous, epididymal, and retroperitoneal WAT depots (SCAT, eWAT, and rpWAT, respectively) were removed for ex vivo experiments and Western blotting. SCAT, eWAT, and rpWAT from a subset of rats were also cultured separately and received a single in vitro HT or sham treatment. HSP72 and HSP25 expression was greatest in more metabolically active WAT depots (i.e., eWAT and rpWAT) compared with the SCAT. Following HT, HSP72 increased in all depots with the greatest induction occurring in the SCAT. In addition, HSP25 increased in the rpWAT and eWAT, while HSP60 increased in the rpWAT only in vivo. Free fatty acid (FFA) release from WAT explants was increased following HT in the rpWAT only, and fatty acid reesterification was decreased in the rpWAT but increased in the SCAT following HT. HT increased insulin responsiveness in eWAT, but not in SCAT or rpWAT. Differences in HSP expression and induction patterns following HT further support the growing body of literature differentiating distinct WAT depots in health and disease.

  17. Heat transfer to deep tissue: the effect of body fat and heating modality.

    PubMed

    Petrofsky, J S; Laymon, M

    2009-01-01

    The purpose of this study was to quantify the thermal transfer characteristics of the skin in relation to body composition as assessed by the ability of water immersion and hot and cold packs with different thicknesses of towels layers to heat or cool deep tissue. Two sets of experiments were conducted to determine the interrelationships between body fat content and muscle temperature after immersion of the limb in water or the application of hot and cold packs. In the first series of experiments, subjects immersed their lower body in water at 42, 37, 34, 27, 24 and 0 degrees C for 20 minutes. Muscle temperature was measured in the skin above and in the belly of the quadriceps and medial gastrocnemius muscles by a thermistor on the skin and one implanted with a 20-gauge needle 25 mm below and perpendicular to the skin. To see the effect of circulation, a series was conducted with the circulation occluded. In the second series, hot or cold packs were used with different thicknesses of towel layers. The muscle temperature after immersion in water approached that of the packs within approximately 20 minutes. In contrast, when hot and cold packs were used with various thickness of towels ranging from 2 to 10 mm in thickness, the change in muscle temperature was much less and it was still changing at the end of a 20 minute period. Subjects with high body fat changed their deep tissue temperatures much more slowly with a time constant nearly double that of the thin subjects with all modalities. Even after water immersion, if the body fat exceeded 25% of the subject's weight, 20 min of immersion was not enough to either warm the muscle or cool it down substantially. Cold packs and hot packs were very ineffective in changing muscle temperature under these same conditions. Body fat plays a major role, as did limb blood flow in controlling the movement of heat across the limb.

  18. Effects of respirators under heat/work conditions

    SciTech Connect

    James, R.; Dukes-Dobos, F.; Smith, R.

    1984-06-01

    Physiological responses and perceived strain of five unacclimatized male subjects were studied. The subjects were exposed to heat during an exercise task and were evaluated while wearing half and full facepiece, cartridge-type, air-purifying respirators, and without a respirator. The exercise consisted of walking on a treadmill for a period of 1 hour in a controlled environmental chamber at each of two different energy expenditure levels (200 and 400 kcal/hr)(approx. = 58 and 116 Watts) and two different heat exposures (air temperatures of 25/sup 0/C and 43.3./sup 0/C). The results indicated that wearing a full facepiece respirator imposed significant physiological strain added to that caused by the heat and workloads used in the study. Five of the six physiological measures show this increased physiological strain: (1) heart rate; (2) minute ventilation; (3) oxygen consumption; (4) energy expenditure; and (5) oral temperature. There was no detectable effect on sweat rate. Although subjective ratings indicated more discomfort with increasing physiological strain, the observed correlations between such measures were low (T/sub b/ < .60). The net consequence of the significant effects indicates that workers' tolerance to moderate or high levels of work under hot conditions while wearing a respirator is reduced. The reduction is more pronounced when wearing a full mask than when wearing a half mask. Changes in respirator design which minimize respiratory dead space are suggested to alleviate this problem. Otherwise, prevention of excessive physiological strain from respirator use when working at moderate or higher levels at hot job sites could necessitate more rest breaks or limiting work time under such conditions.

  19. Effect of ultrahigh-temperature continuous ohmic heating treatment on fresh orange juice.

    PubMed

    Leizerson, Shirly; Shimoni, Eyal

    2005-05-01

    The scope of this study is the effect of ohmic heating thermal treatment on liquid fruit juice made of oranges. Effects of ohmic heating on the quality of orange juice were examined and compared to those of heat pasteurization at 90 degrees C for 50 s. Orange juice was treated at temperatures of 90, 120, and 150 degrees C for 1.13, 0.85, and 0.68 s in an ohmic heating system. Microbial counts showed complete inactivation of bacteria, yeast, and mold during ohmic and conventional treatments. The ohmic heating treatment reduced pectin esterase activity by 98%. The reduction in vitamin C was 15%. Ohmic-heated orange juice maintained higher amounts of the five representative flavor compounds than did heat-pasteurized juice. Sensory evaluation tests showed no difference between fresh and ohmic-heated orange juice. Thus, high-temperature ohmic-heating treatment can be effectively used to pasteurize fresh orange juice with minimal sensory deterioration.

  20. Heat acclimation improves intermittent sprinting in the heat but additional pre-cooling offers no further ergogenic effect.

    PubMed

    Castle, Paul; Mackenzie, Richard W; Maxwell, Neil; Webborn, Anthony D J; Watt, Peter W

    2011-08-01

    The aim of this study was to determine the effect of 10 days of heat acclimation with and without pre-cooling on intermittent sprint exercise performance in the heat. Eight males completed three intermittent cycling sprint protocols before and after 10 days of heat acclimation. Before acclimation, one sprint protocol was conducted in control conditions (21.8 ± 2.2°C, 42.8 ± 6.7% relative humidity) and two sprint protocols in hot, humid conditions (33.3 ± 0.6°C, 52.2 ± 6.8% relative humidity) in a randomized order. One hot, humid condition was preceded by 20 min of thigh pre-cooling with ice packs (-16.2 ± 4.5°C). After heat acclimation, the two hot, humid sprint protocols were repeated. Before heat acclimation, peak power output declined in the heat (P < 0.05) but pre-cooling prevented this. Ten days of heat acclimation reduced resting rectal temperature from 37.8 ± 0.3°C to 37.4 ± 0.3°C (P < 0.01). When acclimated, peak power output increased by ∼2% (P < 0.05, main effect) and no reductions in individual sprint peak power output were observed. Additional pre-cooling offered no further ergogenic effect. Unacclimated athletes competing in the heat should pre-cool to prevent reductions in peak power output, but heat acclimate for an increased peak power output. PMID:21777052

  1. Fast plasma heating by anomalous and inertial resistivity effects

    NASA Technical Reports Server (NTRS)

    Duijveman, A.; Hoyng, P.; Ionson, J. A.

    1981-01-01

    Fast plasma heating by anomalous and inertial resistivity effects is described. A small fraction of the plasma contains strong currents that run parallel to the magnetic field and are driven by an exponentiating electric field. The anomalous character of the current dissipation is caused by the excitation of electrostatic ion cyclotron and/or ion acoustic waves. The role of resistivity due to geometrical effects is considered. Through the use of a marginal stability analysis, equations for the average electron and ion temperatures are derived and numerically solved. The evolution of the plasma is described as a path in the drift velocity diagram, in which the drift velocity is plotted as a function of the electron to ion temperature ratio.

  2. Positive effects of vegetation: urban heat island and green roofs.

    PubMed

    Susca, T; Gaffin, S R; Dell'osso, G R

    2011-01-01

    This paper attempts to evaluate the positive effects of vegetation with a multi-scale approach: an urban and a building scale. Monitoring the urban heat island in four areas of New York City, we have found an average of 2 °C difference of temperatures between the most and the least vegetated areas, ascribable to the substitution of vegetation with man-made building materials. At micro-scale, we have assessed the effect of surface albedo on climate through the use of a climatological model. Then, using the CO(2) equivalents as indicators of the impact on climate, we have compared the surface albedo, and the construction, replacement and use phase of a black, a white and a green roof. By our analyses, we found that both the white and the green roofs are less impactive than the black one; with the thermal resistance, the biological activity of plants and the surface albedo playing a crucial role.

  3. Casimir effect and radiative heat transfer between Chern Insulators

    NASA Astrophysics Data System (ADS)

    Rodriguez Lopez, Pablo; Grushin, Adolfo; Tse, Wang-Kong; Dalvit, Diego

    2015-03-01

    Chern Insulators are a class of two-dimensional topological materials. Their electronic properties are different from conventional materials, and lead to interesting new physics as quantum Hall effect in absence of an external magnetic field. Here we will review some of their special properties and, in particular, we will discuss the radiative heat transfer and the Casimir effect between two planar Chern Insulators sheets. Finally, we will see how to control the intensity and sign of this Casimir force and the requirements to observe a repulsive Casimir force in the lab with those materials. The research leading to these results has received funding from the People Programme (Marie Curie Actions) of the European Union's Seventh Framework Programme (FP7/2007-2013) under REA Grant Agreement No. 302005.

  4. Effect of heating rate on evaporative heat loss in the microwave-exposed mouse

    SciTech Connect

    Gordon, C.J.

    1982-08-01

    Mice were exposed to microwave radiation at 2.450 MHz at varying intensities and heat loads to determine if the animals thermoregulate or temperature regulate in conditions of varying heat load. The mice were exposed to whole-body doses of microwave radiation and power not reflected back was regarded as absorbed by the mouse. Incident powers of three to six watts were used, resulting in specific absorption rates of 47.4-93.4 W/kg. Deep body temperatures and the evaporated heat loss were monitored, and results demonstrated that mice thermoregulate, i.e., dissipate heat loads through evaporative heat loss at a rate which is modeled numerically. It is concluded that a significant portion of the microwave energy is deposited internally.

  5. Does the Heat Island Effect Affect Lake Chabot

    NASA Astrophysics Data System (ADS)

    Singh, K. A.; Mock, Y.; Pun, C.

    2014-12-01

    Lake Chabot is a backup water supply source and it is important to know if the water is healthy because California is experiencing a drought. To check the quality of the water we used a submersible, waterproof thermometer to measure the temperature of the water at different depths. We hypothesized that the heat-island effect would cause the runoff from the surrounding developed areas to be warmer. This is because paving roads causes areas to become impermeable and absorb heat. Water runs off these impermeable surfaces, absorbing heat from the ground and enters larger bodies of water via stream. To locate streams we used a topography map. We located close lines followed by lines that were farther apart and then once again followed by close lines. This indicates that there is a concave area between two high points, allowing water to possibly flow through. We found that areas where the water came from highly populated areas were warmer. The increase in temperature was shown throughout all depths of the water at each site that was measured. The temperature throughout the lake was in between 19°C and 25°C. This warm temperature makes it hard for gases to mix. The lower the dissolved oxygen level, the less desirable it is for a variety of organisms to survive. Higher temperatures also increase bacterial growth and can causes water to be unhealthy. This indicates that the water at Lake Chabot is not suitable for human consumption and should not be considered a suitable backup water source for our area.

  6. Effect of CMC Molecular Weight on Acid-Induced Gelation of Heated WPI-CMC Soluble Complex.

    PubMed

    Huan, Yan; Zhang, Sha; Vardhanabhuti, Bongkosh

    2016-02-01

    Acid-induced gelation properties of heated whey protein isolate (WPI) and carboxymethylcellulose (CMC) soluble complex were investigated as a function of CMC molecular weight (270, 680, and 750 kDa) and concentrations (0% to 0.125%). Heated WPI-CMC soluble complex with 6% protein was made by heating biopolymers together at pH 7.0 and 85 °C for 30 min and diluted to 5% protein before acid-induced gelation. Acid-induced gel formed from heated WPI-CMC complexes exhibited increased hardness and decreased water holding capacity with increasing CMC concentrations but gel strength decreased at higher CMC content. The highest gel strength was observed with CMC 750 k at 0.05%. Gels with low CMC concentration showed homogenous microstructure which was independent of CMC molecular weight, while increasing CMC concentration led to microphase separation with higher CMC molecular weight showing more extensive phase separation. When heated WPI-CMC complexes were prepared at 9% protein the acid gels showed improved gel hardness and water holding capacity, which was supported by the more interconnected protein network with less porosity when compared to complexes heated at 6% protein. It is concluded that protein concentration and biopolymer ratio during complex formation are the major factors affecting gel properties while the effect of CMC molecular weight was less significant.

  7. The effects of orbital and climatic variations on Martian surface heat flow

    NASA Technical Reports Server (NTRS)

    Mellon, Michael T.; Jakosky, Bruce M.

    1992-01-01

    We have examined the effects of climate changes, induced by orbital oscillations, on Martian surface heat flow. It was found that the climatological component of the surface heat flow can be larger than the expected internal geothermal heat flow. We suggest that measurements of surface heat flow be targeted for equatorial and south polar regions to avoid climatic effects and that care be taken in interpreting measurements in mid-latitude and north polar regions.

  8. Effect of reactor heat transfer limitations on CO preferential oxidation

    NASA Astrophysics Data System (ADS)

    Ouyang, X.; Besser, R. S.

    Our recent studies of CO preferential oxidation (PrOx) identified systematic differences between the characteristic curves of CO conversion for a microchannel reactor with thin-film wall catalyst and conventional mini packed-bed lab reactors (m-PBR's). Strong evidence has suggested that the reverse water-gas-shift (r-WGS) side reaction activated by temperature gradients in m-PBR's is the source of these differences. In the present work, a quasi-3D tubular non-isothermal reactor model based on the finite difference method was constructed to quantitatively study the effect of heat transport resistance on PrOx reaction behavior. First, the kinetic expressions for the three principal reactions involved were formed based on the combination of experimental data and literature reports and their parameters were evaluated with a non-linear regression method. Based on the resulting kinetic model and an energy balance derived for PrOx, the finite difference method was then adopted for the quasi-3D model. This model was then used to simulate both the microreactor and m-PBR's and to gain insights into their different conversion behavior. Simulation showed that the temperature gradients in m-PBR's favor the reverse water-gas-shift (r-WGS) reaction, thus causing a much narrower range of permissible operating temperature compared to the microreactor. Accordingly, the extremely efficient heat removal of the microchannel/thin-film catalyst system eliminates temperature gradients and efficiently prevents the onset of the r-WGS reaction.

  9. Polymorphism, microstructure and rheology of butter. Effects of cream heat treatment.

    PubMed

    Rønholt, Stine; Kirkensgaard, Jacob Judas Kain; Pedersen, Thomas Bæk; Mortensen, Kell; Knudsen, Jes Christian

    2012-12-01

    The effect of cream heat treatment prior to butter manufacturing, fluctuating temperatures during storage and presence of fat globules vs. no fat globules was examined in laboratory scale produced butter. X-ray diffraction and differential scanning calorimetry was used to study crystallization behaviour and nuclear magnetic resonance to measure solid fat content and water droplet size distribution. Furthermore, the crystal structure was linked to the rheological properties and microstructure of the butter using confocal laser scanning microscopy. Butter produced from non-matured cream mainly formed α- and β'-crystals with minor traces of β-crystals. Maturing of the cream caused a transition from α- to β'- and β-form. The rheological behaviour of slow cooled butter deviated from the matured ones by having a lower elastic modulus, caused by a weaker crystal network. Presence of fat globules did not affect the rheological properties significantly.

  10. Mechanical effects of heat-moisture exchangers in ventilated patients.

    PubMed

    Iotti, G A; Olivei, M C; Braschi, A

    1999-01-01

    Although they represent a valuable alternative to heated humidifiers, artificial noses have unfavourable mechanical effects. Most important of these is the increase in dead space, with consequent increase in the ventilation requirement. Also, artificial noses increase the inspiratory and expiratory resistance of the apparatus, and may mildly increase intrinsic positive end-expiratory pressure. The significance of these effects depends on the design and function of the artificial nose. The pure humidifying function results in just a moderate increase in dead space and resistance of the apparatus, whereas the combination of a filtering function with the humidifying function may critically increase the volume and the resistance of the artificial nose, especially when a mechanical filter is used. The increase in the inspiratory load of ventilation that is imposed by artificial noses, which is particularly significant for the combined heat-moisture exchanger filters, should be compensated for by an increase either in ventilator output or in patient's work of breathing. Although both approaches can be tolerated by most patients, some exceptions should be considered. The increased pressure and volume that are required to compensate for the artificial nose application increase the risk of barotrauma and volutrauma in those patients who have the most severe alterations in respiratory mechanics. Moreover, those patients who have very limited respiratory reserve may not be able to compensate for the inspiratory work imposed by an artificial nose. When we choose an artificial nose, we should take into account the volume and resistance of the available devices. We should also consider the mechanical effects of the artificial noses when setting mechanical ventilation and when assessing a patient's ability to breathe spontaneously.

  11. Determining the effects of microwave heating on the ordered structures of rice starch by NMR.

    PubMed

    Fan, Daming; Ma, Wenrui; Wang, Liyun; Huang, Jianlian; Zhang, Fengmin; Zhao, Jianxin; Zhang, Hao; Chen, Wei

    2013-02-15

    The effects of microwave heating on the double helices, single helix and amorphous structures and the relative crystallinity of rice starch were studied by (13)C CP/MAS NMR method, with rapid heating in an oil bath and conventional slow heating as controls. The results indicated that compared with rapid heating, microwave heating did not significantly change the ordered and disordered structures. All of the heating methods exhibited similar content changes to the double helices, V-type single helix and amorphous structures with rising temperature. The rapid heating effects caused by microwave and oil bath accelerated the destruction of the V-type single helix in the starch granules. The electromagnetic effect of microwave heating did not affect the decrease of the double helices or the amorphous content of the starch.

  12. Effect on the flow and heat transfer characteristics for sinusoidal pulsating laminar flow in a heated square cylinder

    NASA Astrophysics Data System (ADS)

    Yu, Jiu-Yang; Lin, Wei; Zheng, Xiao-Tao

    2014-06-01

    Two-dimensional numerical simulation is performed to understand the effect of flow pulsation on the flow and heat transfer from a heated square cylinder at Re = 100. Numerical calculations are carried out by using a finite volume method based on the pressure-implicit with splitting of operators algorithm in a collocated grid. The effects of flow pulsation amplitude (0.2 ≤ A ≤ 0.8) and frequency (0 ≤ f p ≤ 20 Hz) on the detailed kinematics of flow (streamlines, vorticity patterns), the macroscopic parameters (drag coefficient, vortex shedding frequency) and heat transfer enhancement are presented in detail. The Strouhal number of vortices shedding, drag coefficient for non-pulsating flow are compared with the previously published data, and good agreement is found. The lock-on phenomenon is observed for a square cylinder in the present flow pulsation. When the pulsating frequency is within the lock-on regime, time averaged drag coefficient and heat transfer from the square cylinder is substantially augmented, and when the pulsating frequency in about the natural vortex shedding frequency, the heat transfer is also substantially enhanced. In addition, the influence of the pulsating amplitude on the time averaged drag coefficient, heat transfer enhancement and lock-on occurrence is discussed in detail.

  13. HEAT INPUT AND POST WELD HEAT TREATMENT EFFECTS ON REDUCED-ACTIVATION FERRITIC/MARTENSITIC STEEL FRICTION STIR WELDS

    SciTech Connect

    Tang, Wei; Chen, Gaoqiang; Chen, Jian; Yu, Xinghua; Frederick, David Alan; Feng, Zhili

    2015-01-01

    Reduced-activation ferritic/martensitic (RAFM) steels are an important class of structural materials for fusion reactor internals developed in recent years because of their improved irradiation resistance. However, they can suffer from welding induced property degradations. In this paper, a solid phase joining technology friction stir welding (FSW) was adopted to join a RAFM steel Eurofer 97 and different FSW parameters/heat input were chosen to produce welds. FSW response parameters, joint microstructures and microhardness were investigated to reveal relationships among welding heat input, weld structure characterization and mechanical properties. In general, FSW heat input results in high hardness inside the stir zone mostly due to a martensitic transformation. It is possible to produce friction stir welds similar to but not with exactly the same base metal hardness when using low power input because of other hardening mechanisms. Further, post weld heat treatment (PWHT) is a very effective way to reduce FSW stir zone hardness values.

  14. Film cooling effectiveness and heat transfer with injection through holes

    NASA Technical Reports Server (NTRS)

    Eriksen, V. L.

    1971-01-01

    An experimental investigation of the local film cooling effectiveness and heat transfer downstream of injection of air through discrete holes into a turbulent boundary layer of air on a flat plate is reported. Secondary air is injected through a single hole normal to the main flow and through both a single hole and a row of holes spaced at three diameter intervals with an injection angle of 35 deg to the main flow. Two values of the mainstream Reynolds number are used; the blowing rate is varied from 0.1 to 2.0. Photographs of a carbon dioxide-water fog injected into the main flow at an angle of 90 deg are also presented to show interaction between the jet and mainstream.

  15. Social networks and trade of services: modelling interregional flows with spatial and network autocorrelation effects

    NASA Astrophysics Data System (ADS)

    de la Mata, Tamara; Llano, Carlos

    2013-07-01

    Recent literature on border effect has fostered research on informal barriers to trade and the role played by network dependencies. In relation to social networks, it has been shown that intensity of trade in goods is positively correlated with migration flows between pairs of countries/regions. In this article, we investigate whether such a relation also holds for interregional trade of services. We also consider whether interregional trade flows in services linked with tourism exhibit spatial and/or social network dependence. Conventional empirical gravity models assume the magnitude of bilateral flows between regions is independent of flows to/from regions located nearby in space, or flows to/from regions related through social/cultural/ethic network connections. With this aim, we provide estimates from a set of gravity models showing evidence of statistically significant spatial and network (demographic) dependence in the bilateral flows of the trade of services considered. The analysis has been applied to the Spanish intra- and interregional monetary flows of services from the accommodation, restaurants and travel agencies for the period 2000-2009, using alternative datasets for the migration stocks and definitions of network effects.

  16. Effect of dry heating with ionic gums on physicochemical properties of starch.

    PubMed

    Sun, Qingjie; Si, Fumei; Xiong, Liu; Chu, Lijun

    2013-02-15

    Corn starch, potato starch, pea starch were impregnated with ionic gums (sodium alginate, CMC, and xanthan, 1% based on starch solids) and heat-treated in a dry state for 0, 2, or 4 h at 130°C. Effects of the dry heating on paste viscosity (RVA), microstructure and thermal properties were examined. Dry heat treatment with ionic gums reduced the pasting temperature of the three starches. Heating with xanthan increased the paste viscosity of corn and potato starch. With heat treatment, the paste viscosity of all the starch-sodium alginate mixtures decreased. Heating with CMC increased the paste viscosity of potato starch, but decreased that of corn and pea starch. After dry-heating, To, Tp and Tc of potato starch with ionic gums decreased significantly. SEM of potato starch with CMC showed that the gel structure got compacter after drying-heating. Heat treatment obviously improved the functional properties of the three starches. PMID:23194543

  17. Spatial effects in real networks: Measures, null models, and applications

    NASA Astrophysics Data System (ADS)

    Ruzzenenti, Franco; Picciolo, Francesco; Basosi, Riccardo; Garlaschelli, Diego

    2012-12-01

    Spatially embedded networks are shaped by a combination of purely topological (space-independent) and space-dependent formation rules. While it is quite easy to artificially generate networks where the relative importance of these two factors can be varied arbitrarily, it is much more difficult to disentangle these two architectural effects in real networks. Here we propose a solution to this problem, by introducing global and local measures of spatial effects that, through a comparison with adequate null models, effectively filter out the spurious contribution of nonspatial constraints. Our filtering allows us to consistently compare different embedded networks or different historical snapshots of the same network. As a challenging application we analyze the World Trade Web, whose topology is known to depend on geographic distances but is also strongly determined by nonspatial constraints (degree sequence or gross domestic product). Remarkably, we are able to detect weak but significant spatial effects both locally and globally in the network, showing that our method succeeds in retrieving spatial information even when nonspatial factors dominate. We finally relate our results to the economic literature on gravity models and trade globalization.

  18. Network-level fallout radiation effects assessment. Final report

    SciTech Connect

    Not Available

    1991-05-01

    National Security calls for the ability to maintain communication capabilities in times of national disaster, which could include a nuclear attack. Nuclear detonation has two basic by-products for which telecommunication equipments are susceptible to damage. These are electromagnetic pulse (EMP) and fallout radiation. The purposes of the EMP Mitigation Program are to analyze and to lessen the effects of EMP and fallout radiation on national telecommunications resources. Fallout radiation occurs after the initial intense high-frequency EMP, and is the subject of this analysis. Fallout radiation is the residual radiation that remains in the atmosphere after a nuclear blast, and which can be carried by weather conditions to locations far from the detonation point. This analysis focuses on the effects of fallout radiation on the telecommunications network of the American Telephone and Telegraph Co. (AT and T). This assessment of AT and T-network's communications-capabilities uses a network-level approach to assess fallout-radiation effects on the network's performance. The approach used was developed for assessing network-level EMP effects on Public Switched Network communication capabilities. Details are given on how EMP assessments utilize this method. Equipment-level fallout-radiation survivability data is also required.

  19. Gravity effects on information filtering and network evolving.

    PubMed

    Liu, Jin-Hu; Zhang, Zi-Ke; Chen, Lingjiao; Liu, Chuang; Yang, Chengcheng; Wang, Xueqi

    2014-01-01

    In this paper, based on the gravity principle of classical physics, we propose a tunable gravity-based model, which considers tag usage pattern to weigh both the mass and distance of network nodes. We then apply this model in solving the problems of information filtering and network evolving. Experimental results on two real-world data sets, Del.icio.us and MovieLens, show that it can not only enhance the algorithmic performance, but can also better characterize the properties of real networks. This work may shed some light on the in-depth understanding of the effect of gravity model.

  20. Wireless sensor network for remote monitoring of parameters in distribution points of district utilities for heat and water

    NASA Astrophysics Data System (ADS)

    Drumea, Andrei; Ilie, Ioana; Vasile, Alexandru; Svasta, Paul; Tapu, Adina

    2009-01-01

    Rigorous monitoring of technological parameters optimizes the activities and reduces energy losses in distribution points of heat and water from utility companies. Extra efficiency can be achieved by remote monitoring via Internet or GSM communications and using networks of wireless sensors for collecting data. Presented paper focuses on hardware and software design aspects of wireless sensors for measuring parameters required by water and heat distribution, with focus on flow and temperature measurement. The sensors consist of two modules - one control and communication unit and sensing unit. Sensing unit is specific to measured parameter (flow, temperature, humidity etc.) but control and communication unit is the same for all sensors. Software for sensing unit was developed and tested on a universal electronic module for industrial control. Sensors group together in a plug-and-play wireless mesh network and one of them is connected to an Internet/GSM communication module for remote access. Wireless sensors are battery based devices so energy management issues (hardware and software) play a big role in sensor design. Current consumption of different configurations and in different operation states is analyzed.

  1. Cost-effective network design for groundwater flow monitoring

    NASA Astrophysics Data System (ADS)

    Andricevic, R.

    1990-03-01

    The extensive use of groundwater resources has increased the need for developing cost-effective monitoring networks to provide an indication of the degree to which the subsurface environment has been affected by human activities. This study presents a cost-effective approach to the design of groundwater flow monitoring networks. The groundwater network design is formulated with two problem formats: maximizing the statistical monitoring power for specified budget constraint and minimizing monitoring cost for statistical power requirement. The statistical monitoring power constraint is introduced with an information reliability threshold value. A branch and bound technique is employed to select the optimal solution from a discrete set of possible network alternatives. The method is tested to the design of groundwater flow monitoring problem in the Pomona County, California.

  2. Effects of forced convection of heated air on insensible water loss and heat loss in preterm infants in incubators.

    PubMed

    Okken, A; Blijham, C; Franz, W; Bohn, E

    1982-07-01

    To assess the effect of forced convection of heated air exchange in preterm infants in conventional incubators, we measured insensible water loss and total heat loss in preterm infants in a conventional forced convection incubator (air velocity 15 to 25 cm/second) and in a specially constructed still-air incubator (air velocity 0 to 2 cm/second) at equal operative temperature and humidity. Under the forced conditions, insensible water loss in the preterm infants increased by a mean 52% from 1.04 +/- 0.24 (mean +/- SD) to 1.58 +/- 0.51 ml/kg/hour (P less than 0.001). The ensuing increase in evaporative heat loss was partly reflected in the small but significant increase in total heat loss from 1.65 +/- 0.47 to 1.80 +/- 0.44 kcal/kg/hour (P less than 0.02). In the forced convection incubator, the increased evaporative heat loss in preterm infants was apparently partly compensated by a decreased nonevaporative heat loss. If reduction of insensible water loss is required, preterm infants should not be subjected to forced convection in incubators.

  3. Effects of heat shock protein 90 expression on pectoralis major oxidation in broilers exposed to acute heat stress.

    PubMed

    Hao, Y; Gu, X H

    2014-11-01

    This study was conducted to determine the effects of heat shock protein 90 (HSP90) expression on pH, lipid peroxidation, heat shock protein 70 (HSP70), and glucocorticoid receptor (GR) expression of pectoralis major in broilers exposed to acute heat stress. In total, 90 male broilers were randomly allocated to 3 groups: control (CON), heat stress (HS), or geldanamycin treatment (GA). On d 41, the broilers in the GA group were injected intraperitoneally with GA (5 μg/kg of BW), and the broilers in the CON and HS groups were injected intraperitoneally with saline. Twenty-four hours later, the broilers in the CON group were moved to environmental chambers controlled at 22°C for 2 h, and the broilers in the HS and GA groups were moved to environmental chambers controlled at 40°C for 2 h. The pH values of the pectoralis major after 30 min and 24 h of chilling after slaughter of HS and GA broilers were significantly lower (P < 0.01) than those of the CON broilers. Heat stress caused significant increases in sera corticosterone and lactic dehydrogenase, the activity of malondialdehyde and superoxide dismutase, the expression of HSP90 and HSP70, and nuclear expression of GR protein in the pectoralis major (P < 0.05). Heat stress induced a significant decrease in GR protein expression in the cytoplasm and GR mRNA expression. Furthermore, the low expression of HSP90 significantly increased levels of lactic dehydrogenase and malondialdehyde and GR protein expression in the cytoplasm under heat stress (P < 0.01), and significantly decreased nuclear GR protein expression (P < 0.01). Heat shock protein 90 was positively correlated with corticosterone and superoxide dismutase activities (P < 0.01), and HSP90 mRNA was negatively correlated with pH after chilling for 24 h. The results demonstrated that HSP90 plays a pivotal role in protecting cells from oxidation.

  4. Towards understanding of heat effects in metallic glasses on the basis of macroscopic shear elasticity.

    PubMed

    Mitrofanov, Y P; Wang, D P; Makarov, A S; Wang, W H; Khonik, V A

    2016-03-15

    It is shown that all heat effects taking place upon annealing of a metallic glass within the glassy and supercooled liquid states, i.e. heat release below the glass transition temperature and heat absorption above it, as well as crystallization-induced heat release, are related to the macroscopic shear elasticity. The underlying physical reason can be understood as relaxation in the system of interstitialcy-type "defects" (elastic dipoles) frozen-in from the melt upon glass production.

  5. Towards understanding of heat effects in metallic glasses on the basis of macroscopic shear elasticity

    NASA Astrophysics Data System (ADS)

    Mitrofanov, Y. P.; Wang, D. P.; Makarov, A. S.; Wang, W. H.; Khonik, V. A.

    2016-03-01

    It is shown that all heat effects taking place upon annealing of a metallic glass within the glassy and supercooled liquid states, i.e. heat release below the glass transition temperature and heat absorption above it, as well as crystallization-induced heat release, are related to the macroscopic shear elasticity. The underlying physical reason can be understood as relaxation in the system of interstitialcy-type ”defects” (elastic dipoles) frozen-in from the melt upon glass production.

  6. The Effects of Heat Treatment and Microstructure Variations on Disk Superalloy Properties at High Temperature

    NASA Technical Reports Server (NTRS)

    Gabb, Timothy P.; Gayda, John; Telesman, Jack; Garg, Anita

    2008-01-01

    The effects of heat treatment and resulting microstructure variations on high temperature mechanical properties were assessed for a powder metallurgy disk superalloy LSHR. Blanks were consistently supersolvus solution heat treated and quenched at two cooling rates, than aged at varying temperatures and times. Tensile, creep, and dwell fatigue crack growth tests were then performed at 704 C. Gamma' precipitate microstructures were quantified. Relationships between heat treatment-microstructure, heat treatment-mechanical properties, and microstructure-mechanical properties were assessed.

  7. Resistor-network anomalies in the heat transport of random harmonic chains

    NASA Astrophysics Data System (ADS)

    Weinberg, Isaac; de Leeuw, Yaron; Kottos, Tsampikos; Cohen, Doron

    2016-06-01

    We consider thermal transport in low-dimensional disordered harmonic networks of coupled masses. Utilizing known results regarding Anderson localization, we derive the actual dependence of the thermal conductance G on the length L of the sample. This is required by nanotechnology implementations because for such networks Fourier's law G ∝1 /Lα with α =1 is violated. In particular we consider "glassy" disorder in the coupling constants and find an anomaly which is related by duality to the Lifshitz-tail regime in the standard Anderson model.

  8. Resistor-network anomalies in the heat transport of random harmonic chains.

    PubMed

    Weinberg, Isaac; de Leeuw, Yaron; Kottos, Tsampikos; Cohen, Doron

    2016-06-01

    We consider thermal transport in low-dimensional disordered harmonic networks of coupled masses. Utilizing known results regarding Anderson localization, we derive the actual dependence of the thermal conductance G on the length L of the sample. This is required by nanotechnology implementations because for such networks Fourier's law G∝1/L^{α} with α=1 is violated. In particular we consider "glassy" disorder in the coupling constants and find an anomaly which is related by duality to the Lifshitz-tail regime in the standard Anderson model. PMID:27415239

  9. Effect of planning for connectivity on linear reserve networks.

    PubMed

    Lentini, Pia E; Gibbons, Philip; Carwardine, Josie; Fischer, Joern; Drielsma, Michael; Martin, Tara G

    2013-08-01

    Although the concept of connectivity is decades old, it remains poorly understood and defined, and some argue that habitat quality and area should take precedence in conservation planning instead. However, fragmented landscapes are often characterized by linear features that are inherently connected, such as streams and hedgerows. For these, both representation and connectivity targets may be met with little effect on the cost, area, or quality of the reserve network. We assessed how connectivity approaches affect planning outcomes for linear habitat networks by using the stock-route network of Australia as a case study. With the objective of representing vegetation communities across the network at a minimal cost, we ran scenarios with a range of representation targets (10%, 30%, 50%, and 70%) and used 3 approaches to account for connectivity (boundary length modifier, Euclidean distance, and landscape-value [LV]). We found that decisions regarding the target and connectivity approach used affected the spatial allocation of reserve systems. At targets ≥50%, networks designed with the Euclidean distance and LV approaches consisted of a greater number of small reserves. Hence, by maximizing both representation and connectivity, these networks compromised on larger contiguous areas. However, targets this high are rarely used in real-world conservation planning. Approaches for incorporating connectivity into the planning of linear reserve networks that account for both the spatial arrangement of reserves and the characteristics of the intervening matrix highlight important sections that link the landscape and that may otherwise be overlooked.

  10. Community Size Effects on Epidemic Spreading in Multiplex Social Networks

    PubMed Central

    Liu, Ting; Li, Ping; Chen, Yan; Zhang, Jie

    2016-01-01

    The dynamical process of epidemic spreading has drawn much attention of the complex network community. In the network paradigm, diseases spread from one person to another through the social ties amongst the population. There are a variety of factors that govern the processes of disease spreading on the networks. A common but not negligible factor is people’s reaction to the outbreak of epidemics. Such reaction can be related information dissemination or self-protection. In this work, we explore the interactions between disease spreading and population response in terms of information diffusion and individuals’ alertness. We model the system by mapping multiplex networks into two-layer networks and incorporating individuals’ risk awareness, on the assumption that their response to the disease spreading depends on the size of the community they belong to. By comparing the final incidence of diseases in multiplex networks, we find that there is considerable mitigation of diseases spreading for full phase of spreading speed when individuals’ protection responses are introduced. Interestingly, the degree of community overlap between the two layers is found to be critical factor that affects the final incidence. We also analyze the consequences of the epidemic incidence in communities with different sizes and the impacts of community overlap between two layers. Specifically, as the diseases information makes individuals alert and take measures to prevent the diseases, the effective protection is more striking in small community. These phenomena can be explained by the multiplexity of the networked system and the competition between two spreading processes. PMID:27007112

  11. Effectiveness of sanitizers, dry heat, hot water, and gas catalytic infrared heat treatments to inactivate Salmonella on almonds.

    PubMed

    Bari, Md Latiful; Nei, Daisuke; Sotome, Itaru; Nishina, Ikuo; Isobe, Seiichi; Kawamoto, Shinnichi

    2009-10-01

    The majority of almond-related foodborne outbreaks have been associated with Salmonella. Therefore, it is necessary to find an effective method to inactivate these organisms on raw almond prior to market distribution. This study was conducted to assess the effectiveness of sanitizers (strong or mild electrolyzed water, ozonated water, and distilled water), dry heat treatment, and hot water treatments followed by catalytic infrared (IR) heat treatment to inactivate Salmonella populations on raw almond. Raw almonds inoculated with four-strain cocktails of Salmonella were treated either by soaking in different chemical sanitizers or with dry heat and/or hot water for various periods of time followed by catalytic IR heat treatment for 70 seconds. The treated seeds were then assessed for the efficacy of the treatment in reducing populations of the pathogens. After inoculation and air-drying, 5.73 +/- 0.12 log colony-forming units (CFU)/g Salmonella were detected in nonselective medium. Sanitizer treatment alone did not show significant reduction in the Salmonella population, but in combination with IR drying it reduced the population to 3.0 log CFU/g. Dry heating at 60 degrees C for 4 days followed by IR drying for 70 seconds reduced the Salmonella population an additional 1.0 log CFU/g. Hot water treatments at 85 degrees C for 40 seconds followed by IR drying for 70 seconds reduced pathogens to an undetectable level by direct plating, but not by enrichment. PMID:19622034

  12. Scalable 3D bicontinuous fluid networks: polymer heat exchangers toward artificial organs.

    PubMed

    Roper, Christopher S; Schubert, Randall C; Maloney, Kevin J; Page, David; Ro, Christopher J; Yang, Sophia S; Jacobsen, Alan J

    2015-04-17

    A scalable method for fabricating architected materials well-suited for heat and mass exchange is presented. These materials exhibit unprecedented combinations of small hydraulic diameters (13.0-0.09 mm) and large hydraulic-diameter-to-thickness ratios (5.0-30,100). This process expands the range of material architectures achievable starting from photopolymer waveguide lattices or additive manufacturing.

  13. Heating surface material’s effect on subcooled flow boiling heat transfer of R134a

    SciTech Connect

    Ling Zou; Barclay G. Jones

    2012-11-01

    In this study, subcooled flow boiling of R134a on copper (Cu) and stainless steel (SS) heating surfaces was experimentally investigated from both macroscopic and microscopic points of view. By utilizing a high-speed digital camera, bubble growth rate, bubble departure size, and nucleation site density, were able to be observed and analyzed from the microscopic point of view. Macroscopic characteristics of the subcooled flow boiling, such as heat transfer coefficient, were able to be measured as well. Experimental results showed that there are no obvious difference between the copper and the stainless surface with respect to bubble dynamics, such as contact angle, growth rate and departure size. On the contrary, the results clearly showed a trend that the copper surface had a better performance than the stainless steel surface in terms of heat transfer coefficient. It was also observed that wall heat fluxes on both surfaces were found highly correlated with nucleation site density, as bubble hydrodynamics are similar on these two surfaces. The difference between these two surfaces was concluded as results of different surface thermal conductivities.

  14. Effects of Temperature Gradients and Heat Fluxes on High-Temperature Oxidation

    SciTech Connect

    Holcomb, G.R.

    2008-04-01

    The effects of a temperature gradient and heat flux on point defect diffusion in protective oxide scales were examined. Irreversible thermodynamics were used to expand Fick’s first law of diffusion to include a heat-flux term—a Soret effect. Oxidation kinetics were developed for the oxidation of cobalt and of nickel doped with chromium. Research is described to verify the effects of a heat flux by oxidizing pure cobalt in a temperature gradient at 900 °C, and comparing the kinetics to isothermal oxidation. No evidence of a heat flux effect was found.

  15. Magnetoresistance effect of heat generation in a single-molecular spin-valve

    NASA Astrophysics Data System (ADS)

    Jiang, Feng; Yan, Yonghong; Wang, Shikuan; Yan, Yijing

    2016-02-01

    Based on non-equilibrium Green's functions' theory and small polaron transformation's technology, we study the heat generation by current through a single-molecular spin-valve. Numerical results indicate that the variation of spin polarization degree can change heat generation effectively, the spin-valve effect happens not only in electrical current but also in heat generation when Coulomb repulsion in quantum dot is smaller than phonon frequency and interestingly, when Coulomb repulsion is larger than phonon frequency, the inverse spin-valve effect appears by sweeping gate voltage and is enlarged with bias increasing. The inverse spin-valve effect will induce the unique heat magnetoresistance effect, which can be modulated from heat-resistance to heat-gain by gate voltage easily.

  16. Effects of Route Guidance Systems on Small-World Networks

    NASA Astrophysics Data System (ADS)

    Wu, Jian-Jun; Sun, Hui-Jun; Gao, Zi-You; Li, Shu-Bin

    The route guidance systems (RGS) are efficient in alleviating traffic congestion and reducing transit time of transportation networks. This paper studies the effects of RGS on performance of variably weighted small-world networks. The properties of the average shortest path length, the maximum degree, and the largest betweenness, as important indices for characterizing the network structure in complex networks, are simulated. Results show that there is an optimal guided rate of RGS to minimize the total system cost and the average shortest path length, and proper RGS can reduce the load of the node with maximum degree or largest betweenness. In addition, we found that the load distribution of nodes guided by RGS decay as the power laws which is very important for us to understand and control traffic congestion feasible.

  17. Structural Effects on the Friction of Tethered PDMS Networks

    NASA Astrophysics Data System (ADS)

    Cohen, Claude; Landherr, Lucas; Archer, Lynden

    2011-03-01

    The interfacial properties of dry, surface-tethered end-linked polydimethylsiloxane (PDMS) films on silicon are examined. Thin network films (approximately 10 microns thick) were synthesized over a self-assembled monolayer supported on a silicon wafer. By systematically increasing the concentration of mono-functional PDMS chains in a mixture with telechelic precursor chains during cross-linking, structures ranging from near model elastic networks to very poorly cross-linked networks dominated by a preponderance of dangling/pendent chains were synthesized. Lateral force microscopy (LFM) employing a PE bead probe was used to quantify the effect of network structure and the role of viscoelasticity on the interfacial friction coefficient. Supported by DOE Grant DE-FG02-07ER46455 and NSF Grant DMR-0705565.

  18. Heat and storage effects on the flavour of peanuts.

    PubMed

    el-Kayati, S M; Fadel, H H; Abdel Mageed, M; Farghal, S A

    1998-12-01

    Two peanut varieties, Giza 4 and Giza 5 were subjected to different heat treatments such as drying in solar drier at air speed 0.5 and 2 m/sec with average temperature 45 and 60 degrees C and heating in oven at 120 and 150 degrees C. The sensory evaluation of the two varieties showed insignificant differences among varieties and heating processes. A correlation between the sensory and instrumental data was found. The high sensory scores of samples heated at 150 degrees C were attributed to the presence of high concentration of pyrazines which were thought to contribute to flavour and aroma of fresh roasted peanut. A comparative study between the main chemical classes retained in peanut samples after storage for 3 months at room temperature showed that the aldehydes derived lipids increased significantly in the solar dried samples. The antioxidative components produced via Maillard reaction resulted in oxidative stability of the samples heated in oven. PMID:9881373

  19. Heat and storage effects on the flavour of peanuts.

    PubMed

    el-Kayati, S M; Fadel, H H; Abdel Mageed, M; Farghal, S A

    1998-12-01

    Two peanut varieties, Giza 4 and Giza 5 were subjected to different heat treatments such as drying in solar drier at air speed 0.5 and 2 m/sec with average temperature 45 and 60 degrees C and heating in oven at 120 and 150 degrees C. The sensory evaluation of the two varieties showed insignificant differences among varieties and heating processes. A correlation between the sensory and instrumental data was found. The high sensory scores of samples heated at 150 degrees C were attributed to the presence of high concentration of pyrazines which were thought to contribute to flavour and aroma of fresh roasted peanut. A comparative study between the main chemical classes retained in peanut samples after storage for 3 months at room temperature showed that the aldehydes derived lipids increased significantly in the solar dried samples. The antioxidative components produced via Maillard reaction resulted in oxidative stability of the samples heated in oven.

  20. Monitoring the urban heat island of Bucharest (Romania) through a network of automatic meteorological sensors - first results

    NASA Astrophysics Data System (ADS)

    Cheval, Sorin; Lucaschi, Bogdan; Ioja, Cristian; Dumitrescu, Alexandru; Manea, Ancuta; Radulescu, Adrian; Dumitrache, Catalin; Tudorache, George; Vanau, Gabriel; Onose, Diana

    2015-04-01

    Extreme warm temperatures and heat waves represent one of the major climate hazards which impact the city of Bucharest (Romania), favoured by the climate background and by the urban characteristics. Previous studies based either on sparse ground sensors or satellite remote sensing indicate that the average differences between the monthly temperature of the built area and the neighbouring rural buffers of Bucharest can reach 3-4°C, but instantaneous values are certainly higher. Since the city shelters about 2 million residents, as well as the major administrative and economic facilities of the country, the hazard management should receive a vivid attention. The meteorological monitoring of the city is currently performed in a systematic manner by the National Meteorological Administration (NMA) through 3 ground-based stations following the standards of the World Meteorological Organization, and through radar and satellite remote sensing. In 2014, NMA set up 7 automatic sensors in specific urban conditions, while the University of Bucharest deployed 30 mobile sensors in a joint effort for enhancing the accuracy of the urban heat island monitoring. Both sensor devices are designed for continuous monitoring (24/7). This presentation focuses on the technical characteristics of the recently implemented network (1), and brings to the public the first results of the monitoring (2), including the implementation experience, the observed benefits and plans for development and applications. The data obtained are compared with the existing data sets from meteorological stations and satellite products, and they are currently integrated in a common database, providing valuable information about the Bucharest's urban heat island. The results have been obtained within the project UCLIMESA (Urban Heat Island Monitoring under Present and Future Climate), ongoing between 2013 and 2015 in the framework of the Programme for Research-Development-Innovation for Space Technology and

  1. Effects of local and global network connectivity on synergistic epidemics

    NASA Astrophysics Data System (ADS)

    Broder-Rodgers, David; Pérez-Reche, Francisco J.; Taraskin, Sergei N.

    2015-12-01

    Epidemics in networks can be affected by cooperation in transmission of infection and also connectivity between nodes. An interplay between these two properties and their influence on epidemic spread are addressed in the paper. A particular type of cooperative effects (called synergy effects) is considered, where the transmission rate between a pair of nodes depends on the number of infected neighbors. The connectivity effects are studied by constructing networks of different topology, starting with lattices with only local connectivity and then with networks that have both local and global connectivity obtained by random bond-rewiring to nodes within a certain distance. The susceptible-infected-removed epidemics were found to exhibit several interesting effects: (i) for epidemics with strong constructive synergy spreading in networks with high local connectivity, the bond rewiring has a negative role in epidemic spread, i.e., it reduces invasion probability; (ii) in contrast, for epidemics with destructive or weak constructive synergy spreading on networks of arbitrary local connectivity, rewiring helps epidemics to spread; (iii) and, finally, rewiring always enhances the spread of epidemics, independent of synergy, if the local connectivity is low.

  2. Responding to the Effects of Extreme Heat: Baltimore City's Code Red Program.

    PubMed

    Martin, Jennifer L

    2016-01-01

    Heat response plans are becoming increasingly more common as US cities prepare for heat waves and other effects of climate change. Standard elements of heat response plans exist, but plans vary depending on geographic location and distribution of vulnerable populations. Because heat events vary over time and affect populations differently based on vulnerability, it is difficult to compare heat response plans and evaluate responses to heat events. This article provides an overview of the Baltimore City heat response plan, the Code Red program, and discusses the city's response to the 2012 Ohio Valley/Mid Atlantic Derecho, a complex heat event. Challenges with and strategies for evaluating the program are reviewed and shared. PMID:27081886

  3. Effect of heating system using a geothermal heat pump on the production performance and housing environment of broiler chickens.

    PubMed

    Choi, H C; Salim, H M; Akter, N; Na, J C; Kang, H K; Kim, M J; Kim, D W; Bang, H T; Chae, H S; Suh, O S

    2012-02-01

    A geothermal heat pump (GHP) is a potential heat source for the economic heating of broiler houses with optimum production performance. An investigation was conducted to evaluate the effect of a heating system using a GHP on production performance and housing environment of broiler chickens. A comparative analysis was also performed between the GHP system and a conventional heating system that used diesel for fuel. In total, 34,000 one-day-old straight run broiler chicks were assigned to 2 broiler houses with 5 replicates in each (3,400 birds/replicate pen) for 35 d. Oxygen(,) CO(2), and NH(3) concentrations in the broiler house, energy consumption and cost of heating, and production performance of broilers were evaluated. Results showed that the final BW gain significantly (P < 0.05) increased when chicks were reared in the GHP broiler house compared with that of chicks reared in the conventional broiler house (1.73 vs. 1.62 kg/bird). The heating system did not affect the mortality of chicks during the first 4 wk of the experimental period, but the mortality markedly increased in the conventional broiler house during the last wk of the experiment. Oxygen content in the broiler house during the experimental period was not affected by the heating system, but the CO(2) and NH(3) contents significantly increased (P < 0.05) in the conventional broiler house compared with those in the GHP house. Fuel consumption was significantly reduced (P < 0.05) and electricity consumption significantly increased (P < 0.05) in the GHP house compared with the consumption in the conventional house during the experiment. The total energy cost of heating the GHP house was significantly lower (P < 0.05) compared with that of the conventional house. It is concluded that a GHP system could increase the production performance of broiler chicks due to increased inside air quality of the broiler house. The GHP system had lower CO(2) and NH(3) emissions with lower energy cost than the

  4. Effect of heating system using a geothermal heat pump on the production performance and housing environment of broiler chickens.

    PubMed

    Choi, H C; Salim, H M; Akter, N; Na, J C; Kang, H K; Kim, M J; Kim, D W; Bang, H T; Chae, H S; Suh, O S

    2012-02-01

    A geothermal heat pump (GHP) is a potential heat source for the economic heating of broiler houses with optimum production performance. An investigation was conducted to evaluate the effect of a heating system using a GHP on production performance and housing environment of broiler chickens. A comparative analysis was also performed between the GHP system and a conventional heating system that used diesel for fuel. In total, 34,000 one-day-old straight run broiler chicks were assigned to 2 broiler houses with 5 replicates in each (3,400 birds/replicate pen) for 35 d. Oxygen(,) CO(2), and NH(3) concentrations in the broiler house, energy consumption and cost of heating, and production performance of broilers were evaluated. Results showed that the final BW gain significantly (P < 0.05) increased when chicks were reared in the GHP broiler house compared with that of chicks reared in the conventional broiler house (1.73 vs. 1.62 kg/bird). The heating system did not affect the mortality of chicks during the first 4 wk of the experimental period, but the mortality markedly increased in the conventional broiler house during the last wk of the experiment. Oxygen content in the broiler house during the experimental period was not affected by the heating system, but the CO(2) and NH(3) contents significantly increased (P < 0.05) in the conventional broiler house compared with those in the GHP house. Fuel consumption was significantly reduced (P < 0.05) and electricity consumption significantly increased (P < 0.05) in the GHP house compared with the consumption in the conventional house during the experiment. The total energy cost of heating the GHP house was significantly lower (P < 0.05) compared with that of the conventional house. It is concluded that a GHP system could increase the production performance of broiler chicks due to increased inside air quality of the broiler house. The GHP system had lower CO(2) and NH(3) emissions with lower energy cost than the

  5. EFFECT OF HORIZONTALLY INHOMOGENEOUS HEATING ON FLOW AND MAGNETIC FIELD IN THE CHROMOSPHERE OF THE SUN

    SciTech Connect

    Song, P.; Vasyliūnas, V. M.

    2014-12-01

    The solar chromosphere is heated by damped Alfvén waves propagating upward from the photosphere at a rate that depends on magnetic field strength, producing enhanced heating at low altitudes in the extended weak-field regions (where the additional heating accounts for the radiative losses) between the boundaries of the chromospheric network as well as enhanced heating per particle at higher altitudes in strong magnetic field regions of the network. The resulting inhomogeneous radiation and temperature distribution produces bulk flows, which in turn affect the configuration of the magnetic field. The basic flow pattern is circulation on the spatial scale of a supergranule, with upward flow in the strong-field region; this is a mirror image in the upper chromosphere of photospheric/subphotospheric convection widely associated with the formation of the strong network field. There are significant differences between the neutral and the ionized components of the weakly ionized medium: neutral flow streamlines can form closed cells, whereas plasma is largely constrained to flow along the magnetic field. Stresses associated with this differential flow may explain why the canopy/funnel structures of the network magnetic field have a greater horizontal extent and are relatively more homogeneous at high altitudes than is expected from simple current-free models.

  6. Effect of Horizontally Inhomogeneous Heating on Flow and Magnetic Field in the Chromosphere of the Sun

    NASA Astrophysics Data System (ADS)

    Song, P.; Vasyliūnas, V. M.

    2014-12-01

    The solar chromosphere is heated by damped Alfvén waves propagating upward from the photosphere at a rate that depends on magnetic field strength, producing enhanced heating at low altitudes in the extended weak-field regions (where the additional heating accounts for the radiative losses) between the boundaries of the chromospheric network as well as enhanced heating per particle at higher altitudes in strong magnetic field regions of the network. The resulting inhomogeneous radiation and temperature distribution produces bulk flows, which in turn affect the configuration of the magnetic field. The basic flow pattern is circulation on the spatial scale of a supergranule, with upward flow in the strong-field region; this is a mirror image in the upper chromosphere of photospheric/subphotospheric convection widely associated with the formation of the strong network field. There are significant differences between the neutral and the ionized components of the weakly ionized medium: neutral flow streamlines can form closed cells, whereas plasma is largely constrained to flow along the magnetic field. Stresses associated with this differential flow may explain why the canopy/funnel structures of the network magnetic field have a greater horizontal extent and are relatively more homogeneous at high altitudes than is expected from simple current-free models.

  7. Cost effective campaigning in social networks

    NASA Astrophysics Data System (ADS)

    Kotnis, Bhushan; Kuri, Joy

    2016-05-01

    Campaigners are increasingly using online social networking platforms for promoting products, ideas and information. A popular method of promoting a product or even an idea is incentivizing individuals to evangelize the idea vigorously by providing them with referral rewards in the form of discounts, cash backs, or social recognition. Due to budget constraints on scarce resources such as money and manpower, it may not be possible to provide incentives for the entire population, and hence incentives need to be allocated judiciously to appropriate individuals for ensuring the highest possible outreach size. We aim to do the same by formulating and solving an optimization problem using percolation theory. In particular, we compute the set of individuals that are provided incentives for minimizing the expected cost while ensuring a given outreach size. We also solve the problem of computing the set of individuals to be incentivized for maximizing the outreach size for given cost budget. The optimization problem turns out to be non trivial; it involves quantities that need to be computed by numerically solving a fixed point equation. Our primary contribution is, that for a fairly general cost structure, we show that the optimization problems can be solved by solving a simple linear program. We believe that our approach of using percolation theory to formulate an optimization problem is the first of its kind.

  8. Disruption of the three cytoskeletal networks in mammalian cells does not affect transcription, translation, or protein translocation changes induced by heat shock.

    PubMed Central

    Welch, W J; Feramisco, J R

    1985-01-01

    Mammalian cells show a complex series of transcriptional and translational switching events in response to heat shock treatment which ultimately lead to the production and accumulation of a small number of proteins, the so-called heat shock (or stress) proteins. We investigated the heat shock response in both qualitative and quantitative ways in cells that were pretreated with drugs that specifically disrupt one or more of the three major cytoskeletal networks. (These drugs alone, cytochalasin E and colcemid, do not result in induction of the heat shock response.) Our results indicated that disruption of the actin microfilaments, the vimentin-containing intermediate filaments, or the microtubules in living cells does not hinder the ability of the cell to undergo an apparently normal heat shock response. Even when all three networks were simultaneously disrupted (resulting in a loose, baglike appearance of the cells), the cells still underwent a complete heat shock response as assayed by the appearance of the heat shock proteins. In addition, the major induced 72-kilodalton heat shock protein was efficiently translocated from the cytoplasm into its proper location in the nucleus and nucleolus irrespective of the condition of the three cytoskeletal elements. Images PMID:4040602

  9. Metabolic Network Prediction of Drug Side Effects.

    PubMed

    Shaked, Itay; Oberhardt, Matthew A; Atias, Nir; Sharan, Roded; Ruppin, Eytan

    2016-03-23

    Drug side effects levy a massive cost on society through drug failures, morbidity, and mortality cases every year, and their early detection is critically important. Here, we describe the array of model-based phenotype predictors (AMPP), an approach that leverages medical informatics resources and a human genome-scale metabolic model (GSMM) to predict drug side effects. AMPP is substantially predictive (AUC > 0.7) for >70 drug side effects, including very serious ones such as interstitial nephritis and extrapyramidal disorders. We evaluate AMPP's predictive signal through cross-validation, comparison across multiple versions of a side effects database, and co-occurrence analysis of drug side effect associations in scientific abstracts (hypergeometric p value = 2.2e-40). AMPP outperforms a previous biochemical structure-based method in predicting metabolically based side effects (aggregate AUC = 0.65 versus 0.59). Importantly, AMPP enables the identification of key metabolic reactions and biomarkers that are predictive of specific side effects. Taken together, this work lays a foundation for future detection of metabolically grounded side effects during early stages of drug development. PMID:27135366

  10. Effect of heat acclimation on sitting orthostatic tolerance in the heat after 48 and 96 hour bed rest in men

    NASA Technical Reports Server (NTRS)

    Greenleaf, J. E.; Matter, M., Jr.

    1995-01-01

    The purpose of this pilot study was to investigate sitting orthostatic tolerance and determine potentially adverse signs and symptoms that would incapacitate subjects in a hot environment (Gemini reentry cabin temperature profile) after 48 hr and 96 hr of horizontal bed rest (BR), which simulated microgravity deconditioning. Six college men (23-29 yr) were allocated into two groups: heat acclimated (three subjects: No. 1- control, No. 2- 48 hr BR, and No. 3- 96 hr BR) and nonheat acclimated (three subjects: No. 4- control, No. 5- 48 hr BR, and No. 6- 96 hr BR). After BR they sat in an ambient temperature of 57 C (135 F) for 30 min which then was decreased to 49 C (120 F) for up to 480 min. Tolerance time in the heat with seated orthostatic stress was 480 min (subject No. 1) and 180 min (subject No. 4) in the two ambulatory men, but was reduced to 22-150 min in the four bed-rested men irrespective of their heat acclimation status. Although heat acclimation appeared to enhance tolerance and attenuate accompanying physiological responses, as well as ameliorate the frequency and intensity of adverse signs and symptoms at termination of exposure, tolerance was reduced in the bed-rest deconditioned subjects regardless of their acclimation level. Thus, these few collective findings do not indicate an unequivocal positive effect of acute heat acclimation on sitting orthostatic tolerance in acute bed-rest deconditioned subjects.

  11. Effect of local controlled heat on transdermal delivery of nicotine.

    PubMed

    Petersen, Kristian Kjær; Rousing, Mark Lillelund; Jensen, Carina; Arendt-Nielsen, Lars; Gazerani, Parisa

    2011-09-30

    Skin permeability and local blood perfusion are important factors for transdermal drug delivery. Application of heat is expected to enhance microcirculation and local perfusion and/or blood vessel permeability, thus facilitating drug transfer to the systemic circulation. In addition, heating prior to or during topical application of a drug may facilitate skin penetration, increase kinetic energy, and facilitate drug absorption. The aim of the present study was to investigate whether application of controlled local heat would enhance transdermal delivery from the nicotine patch mounted on the upper arm of ten healthy non-smoking male Caucasian subjects. Local skin perfusion was monitored using Laser Doppler Imaging (LDI) at baseline (32 °C) and following application of local controlled heat (43 °C) on the upper arm, where the patch was placed. The residue of the nicotine patches was then examined by High-Performance Liquid Chromatography (HPLC) to indicate the uptake of nicotine from the patch due to the local controlled heat. Controlled heat application (43°C) caused significant cutaneous hyperaemia (up to 9 folds increase in skin perfusion) with an increase in nicotine uptake (up to 13 folds). The method was well tolerated without causing any pain or discomfort. These data suggest that controlled heat application, which is a simple, non-invasive method, can significantly enhance local skin perfusion and drug uptake from patches.

  12. The effects of music on brain functional networks: a network analysis.

    PubMed

    Wu, J; Zhang, J; Ding, X; Li, R; Zhou, C

    2013-10-10

    The human brain can dynamically adapt to the changing surroundings. To explore this issue, we adopted graph theoretical tools to examine changes in electroencephalography (EEG) functional networks while listening to music. Three different excerpts of Chinese Guqin music were played to 16 non-musician subjects. For the main frequency intervals, synchronizations between all pair-wise combinations of EEG electrodes were evaluated with phase lag index (PLI). Then, weighted connectivity networks were created and their organizations were characterized in terms of an average clustering coefficient and characteristic path length. We found an enhanced synchronization level in the alpha2 band during music listening. Music perception showed a decrease of both normalized clustering coefficient and path length in the alpha2 band. Moreover, differences in network measures were not observed between musical excerpts. These experimental results demonstrate an increase of functional connectivity as well as a more random network structure in the alpha2 band during music perception. The present study offers support for the effects of music on human brain functional networks with a trend toward a more efficient but less economical architecture.

  13. The long-term effects of a life-prolonging heat treatment on the Drosophila melanogaster transcriptome suggest that heat shock proteins extend lifespan.

    PubMed

    Sarup, P; Sørensen, P; Loeschcke, V

    2014-02-01

    Heat-induced hormesis, i.e. the beneficial effect of mild heat-induced stress, increases the average lifespan of many organisms. This effect, which depends on the heat shock factor, decreases the log mortality rate weeks after the stress has ceased. To identify candidate genes that mediate this lifespan-prolonging effect late in life, we treated flies with mild heat stress (34 °C for 2 h) 3 times early in life and compared the transcriptomic response in these flies versus non-heat-treated controls 10-51 days after the last heat treatment. We found significant transcriptomic changes in the heat-treated flies. Several hsp70 probe sets were up-regulated 1.7-2-fold in the mildly stressed flies weeks after the last heat treatment (P<0.01). This result was unexpected as the major Drosophila heat shock protein, Hsp70, is reported to return to normal levels of expression shortly after heat stress. We conclude that the heat shock response, and Hsp70 in particular, may be central to the heat-induced increase in the average lifespan in flies that are exposed to mild heat stress early in life.

  14. The effect of a magnetic field on heat transfer in a slotted channel

    SciTech Connect

    Evtushenko, I.A.; Kirillov, I.R.; Sidorenkov, S.S.; Hua, T.Q.; Reed, C.B.

    1994-07-01

    The results of numerical and experimental studies of liquid metal heat transfer in slotted channels in a transverse magnetic field are presented. Test results showed an improvement in heat transfer in a straight channel at low and moderate interaction parameter, N. The Nusselt number at small N (around 120) was up to 2 times higher than in turbulent flow without a magnetic field, Peclet number being equal. This effect of heat transfer enhancement is caused by the generation and development of large scale velocity fluctuations in the near heated wall area. Qualitative and quantitative correlations between heat transfer and velocity fluctuation characteristics are presented.

  15. Effect of heat treatment on precipitation on V-5Cr-5Ti heat BL63

    SciTech Connect

    Gelles, D.S.; Li, H.

    1996-04-01

    The microstructures of V-5Cr-5Ti heat BL63 are compared following heat treatments at 1125{degrees}C for 1 h and 1125{degrees}C for 1 h followed by 890{degrees}C for 24 h. Following the 890{degrees}C treatment, precipitate density was increased due to the presence of a moderate density of highly elongated particles. Microchemical analysis showed that these particles often contained both Ti and V, some particles showed minor amounts of Si, S, and P, but it was also possible to show that these precipitates were enriched in O rather than C or N. Following the 1125{degrees}C heat treatment, only Si was found as a minor impurity in large particles, but S could be identified at grain boundaries, which were coated with a fine distribution of precipitates. The embrittlement observed is ascribed to a combination of interstitial solid solution hardening and grain boundary embrittlement, with interstitial hardening likely the dominant factor.

  16. Guide to effective solar heating and cooling practice

    SciTech Connect

    Powell, P.C.; Fostel, H.F.; Cody, E.P.

    1981-10-01

    A detaled and systematic inventory of technical experiences at residential and commercial solar demonstration sites across the nation is provided, and design approaches are described which have been shown to dramatically improve system performance. A review has been made of nearly one hundred sites which have been instrumented and feeding data continuously into the National Solar Data Network. It is found that the success of individual systems in meeting or exceeding their design targets depends on effectively controlled design, installation, operation and maintenance. However, numerous reported problems have also been due to poor communication between the various parties involved, and additionally due to failure to identify problems as the develop. Overall, such factors appear to have contributed greatly to the general underperformance seen at the sites. It is found that solar systems must be designed to operate efficiently during periods of minimum as well as peak loads. Solar coth the conversion, distribution, and end use of ethanol are all amenable to control or mitigation through andstone (Kfh), and the Hell Creek formation (Khc). Anomaly No. 31 is over an area underlain by Recent alluvium (Qal).

  17. Global and local Joule heating effects seen by DE 2

    NASA Technical Reports Server (NTRS)

    Heelis, R. A.; Coley, W. R.

    1988-01-01

    In the altitude region between 350 and 550 km, variations in the ion temperature principally reflect similar variations in the local frictional heating produced by a velocity difference between the ions and the neutrals. Here, the distribution of the ion temperature in this altitude region is shown, and its attributes in relation to previous work on local Joule heating rates are discussed. In addition to the ion temperature, instrumentation on the DE 2 satellite also provides a measure of the ion velocity vector representative of the total electric field. From this information, the local Joule heating rate is derived. From an estimate of the height-integrated Pedersen conductivity it is also possible to estimate the global (height-integrated) Joule heating rate. Here, the differences and relationships between these various parameters are described.

  18. Effect on Non-Uniform Heat Generation on Thermionic Reactions

    SciTech Connect

    Schock, Alfred

    2012-01-19

    The penalty resulting from non-uniform heat generation in a thermionic reactor is examined. Operation at sub-optimum cesium pressure is shown to reduce this penalty, but at the risk of a condition analogous to burnout. For high pressure diodes, a simple empirical correlation between current, voltage and heat flux is developed and used to analyze the performance penalty associated with two different heat flux profiles, for series-and parallel-connected converters. The results demonstrate that series-connected converters require much finer power flattening than parallel converters. For example, a ±10% variation in heat generation across a series array can result in a 25 to 50% power penalty.

  19. Towards effective flow simulations in realistic discrete fracture networks

    NASA Astrophysics Data System (ADS)

    Berrone, Stefano; Pieraccini, Sandra; Scialò, Stefano

    2016-04-01

    We focus on the simulation of underground flow in fractured media, modeled by means of Discrete Fracture Networks. Focusing on a new recent numerical approach proposed by the authors for tackling the problem avoiding mesh generation problems, we further improve the new family of methods making a step further towards effective simulations of large, multi-scale, heterogeneous networks. Namely, we tackle the imposition of Dirichlet boundary conditions in weak form, in such a way that geometrical complexity of the DFN is not an issue; we effectively solve DFN problems with fracture transmissivities spanning many orders of magnitude and approaching zero; furthermore, we address several numerical issues for improving the numerical solution also in quite challenging networks.

  20. Collective helping and bystander effects in coevolving helping networks

    NASA Astrophysics Data System (ADS)

    Jo, Hang-Hyun; Lee, Hyun Keun; Park, Hyunggyu

    2010-06-01

    We study collective helping behavior and bystander effects in a coevolving helping network model. A node and a link of the network represents an agent who renders or receives help and a friendly relation between agents, respectively. A helping trial of an agent depends on relations with other involved agents and its result (success or failure) updates the relation between the helper and the recipient. We study the network link dynamics and its steady states analytically and numerically. The full phase diagram is presented with various kinds of active and inactive phases and the nature of phase transitions are explored. We find various interesting bystander effects, consistent with the field study results, of which the underlying mechanism is proposed.

  1. [Hair disease or the effect of heat (fire)?].

    PubMed

    Schwerd, W; Müller, V

    1988-01-01

    We found alterations in the ends of a man's hair, changes that were suspected of being incendiary. The hair ends were dull, but there were no typical macroscopic signs of alteration by heat; yet the microscopic findings were clear. Spindle-shaped changes in the hair were interpreted at first as heat damage but could be explained as the results of hair-setting lotion.

  2. Effect of heat-treated noradrenaline on flowering in Lemna.

    PubMed

    Miyawaki, Tatsuya; Matsumoto, Shiomi; Takahashi, Wataru; Tanaka, Osamu

    2013-01-01

    In a previous study, heat-treated noradrenaline induced flowering of the short-day plant Lemna paucicostata Hegelmaier 151. In the present study, we found that heat-treated noradrenaline also had flower-inducing activity in short-day L. paucicostata strains 441 and 6746 and in long-day L. gibba strain G3. The flower-inducing activity in these plants was enhanced by water homogenates of eggplant (Solanum melongena L.). PMID:23832342

  3. Heat shock partially dissociates the overlapping modules of the yeast protein-protein interaction network: a systems level model of adaptation.

    PubMed

    Mihalik, Ágoston; Csermely, Peter

    2011-10-01

    Network analysis became a powerful tool giving new insights to the understanding of cellular behavior. Heat shock, the archetype of stress responses, is a well-characterized and simple model of cellular dynamics. S. cerevisiae is an appropriate model organism, since both its protein-protein interaction network (interactome) and stress response at the gene expression level have been well characterized. However, the analysis of the reorganization of the yeast interactome during stress has not been investigated yet. We calculated the changes of the interaction-weights of the yeast interactome from the changes of mRNA expression levels upon heat shock. The major finding of our study is that heat shock induced a significant decrease in both the overlaps and connections of yeast interactome modules. In agreement with this the weighted diameter of the yeast interactome had a 4.9-fold increase in heat shock. Several key proteins of the heat shock response became centers of heat shock-induced local communities, as well as bridges providing a residual connection of modules after heat shock. The observed changes resemble to a 'stratus-cumulus' type transition of the interactome structure, since the unstressed yeast interactome had a globally connected organization, similar to that of stratus clouds, whereas the heat shocked interactome had a multifocal organization, similar to that of cumulus clouds. Our results showed that heat shock induces a partial disintegration of the global organization of the yeast interactome. This change may be rather general occurring in many types of stresses. Moreover, other complex systems, such as single proteins, social networks and ecosystems may also decrease their inter-modular links, thus develop more compact modules, and display a partial disintegration of their global structure in the initial phase of crisis. Thus, our work may provide a model of a general, system-level adaptation mechanism to environmental changes. PMID:22022244

  4. Heat shock partially dissociates the overlapping modules of the yeast protein-protein interaction network: a systems level model of adaptation.

    PubMed

    Mihalik, Ágoston; Csermely, Peter

    2011-10-01

    Network analysis became a powerful tool giving new insights to the understanding of cellular behavior. Heat shock, the archetype of stress responses, is a well-characterized and simple model of cellular dynamics. S. cerevisiae is an appropriate model organism, since both its protein-protein interaction network (interactome) and stress response at the gene expression level have been well characterized. However, the analysis of the reorganization of the yeast interactome during stress has not been investigated yet. We calculated the changes of the interaction-weights of the yeast interactome from the changes of mRNA expression levels upon heat shock. The major finding of our study is that heat shock induced a significant decrease in both the overlaps and connections of yeast interactome modules. In agreement with this the weighted diameter of the yeast interactome had a 4.9-fold increase in heat shock. Several key proteins of the heat shock response became centers of heat shock-induced local communities, as well as bridges providing a residual connection of modules after heat shock. The observed changes resemble to a 'stratus-cumulus' type transition of the interactome structure, since the unstressed yeast interactome had a globally connected organization, similar to that of stratus clouds, whereas the heat shocked interactome had a multifocal organization, similar to that of cumulus clouds. Our results showed that heat shock induces a partial disintegration of the global organization of the yeast interactome. This change may be rather general occurring in many types of stresses. Moreover, other complex systems, such as single proteins, social networks and ecosystems may also decrease their inter-modular links, thus develop more compact modules, and display a partial disintegration of their global structure in the initial phase of crisis. Thus, our work may provide a model of a general, system-level adaptation mechanism to environmental changes.

  5. Heat Diffusion in Gases, Including Effects of Chemical Reaction

    NASA Technical Reports Server (NTRS)

    Hansen, C. Frederick

    1960-01-01

    The diffusion of heat through gases is treated where the coefficients of thermal conductivity and diffusivity are functions of temperature. The diffusivity is taken proportional to the integral of thermal conductivity, where the gas is ideal, and is considered constant over the temperature interval in which a chemical reaction occurs. The heat diffusion equation is then solved numerically for a semi-infinite gas medium with constant initial and boundary conditions. These solutions are in a dimensionless form applicable to gases in general, and they are used, along with measured shock velocity and heat flux through a shock reflecting surface, to evaluate the integral of thermal conductivity for air up to 5000 degrees Kelvin. This integral has the properties of a heat flux potential and replaces temperature as the dependent variable for problems of heat diffusion in media with variable coefficients. Examples are given in which the heat flux at the stagnation region of blunt hypersonic bodies is expressed in terms of this potential.

  6. The effect of passive heating and head cooling on perception, cardiovascular function and cognitive performance in the heat.

    PubMed

    Simmons, Shona E; Saxby, Brian K; McGlone, Francis P; Jones, David A

    2008-09-01

    The present study examined the effects of raising both skin temperature and core temperature, separately and in combination, on perceptions of heat-related fatigue (alertness, contentment, calmness and thermal comfort), cardiovascular function and on objective measures of cognitive performance (reaction time and accuracy). Ten (six males) subjects had cognitive performance assessed in three conditions; at low skin and low core temperature (LL), at high skin and low core temperature (HL) and at high skin and high core temperatures (HH). In one trial, subjects had their head and neck cooled (HC); the other trial was a control (CON). Raising skin temperature increased heart rate and decreased perception of thermal comfort (P < 0.05), whereas raising both skin and core temperature decreased perception of heat-related fatigue (P < 0.05) and increased cardiovascular strain (P < 0.05) resulting in decrements in cognitive performance shown by faster reaction times (P < 0.05) and a loss of accuracy (P < 0.05). At high skin and core temperatures, cooling the head and neck improved feelings of heat-related fatigue (P < 0.05) and cardiovascular strain (P < 0.05), but had no effect on cognitive performance. In conclusion, the results of this study suggest that feelings of heat-related fatigue and cardiovascular strain can be attributed to a combination of elevated skin and core body temperature, whereas decrements in cognitive performance can be attributed to an elevated core temperature.

  7. The effects of Sao Paulo urban heat island on lightning activity: Decadal analysis (1999-2009)

    NASA Astrophysics Data System (ADS)

    Bourscheidt, Vandoir; Pinto, Osmar; Naccarato, Kleber P.

    2016-05-01

    Eleven years of lightning data from the Brazilian Integrated National Lightning Detection Network were used to analyze the effects of the urban heat island (UHI) of Sao Paulo on lightning activity, extending the investigation of previous works. Cloud-to-ground lightning data were analyzed in both spatial and temporal perspectives, using different approaches: flash density, flash rate, thunderstorm hours (TH), and the cell initiation technique (CIT), which aims to identify the onset of thunderstorms. Land surface temperature (LST) from MODIS (Moderate Resolution Imaging Spectroradiometer) was used to analyze the UHI evolution over the years. MODIS data were validated using ground stations, distributed within the urban area. Different time intervals (seasonal and intraday) were used in an attempt to separate local convective systems from synoptic-scale events. The results indicate significant effects of the UHI (using LST) on THs and CIT. The CIT showed a nearly ring pattern, especially during the afternoon (14:00-18:00 LT) of summer months, reinforcing temperature contrast as a condition for storm initiation. The results also suggest an amplification of the UHI effects on thunderstorm activity by local factors (sea and country breeze, synoptic events, and terrain). Higher flash rates were also observed throughout the urban region, which influences the lightning density. Temporal analysis indicates that minimum temperature and lightning activity increase in wintertime. In summary, the results agree with previous studies about the UHI and indicate its importance on lightning occurrence, especially by increasing the temperature contrast and the instability in these regions.

  8. Investigations on the heating effect of PE-LD induced by high-intensity focused ultrasound.

    PubMed

    Oehm, Lukas; Bach, Sascha; Majschak, Jens-Peter

    2016-08-01

    High-intensity focused ultrasound is widely applied in tissue treatment as well as for heating of solid polymer materials. Previous studies investigating the heating effect in polymer materials utilized sound transmission through water or other fluids at low HIFU power. In this study, the ultrasonic transducer possesses a solid sound conductor made of aluminum and a high HIFU power of above 100W was applied to heat solid PE-LD samples. Temperature measurements were performed by calibrated non-invasive infrared thermal imaging. A strong heating effect with heating above melting temperature and evaporation temperature within less than 1s of irradiation was observed. Furthermore, the acoustic coupling defined by the force applied by the ultrasonic applicator to the polymer material was found to be fundamental to induce the heating effect. This investigation reveals HIFU for new applications in the field of polymer processing.

  9. Investigations on the heating effect of PE-LD induced by high-intensity focused ultrasound.

    PubMed

    Oehm, Lukas; Bach, Sascha; Majschak, Jens-Peter

    2016-08-01

    High-intensity focused ultrasound is widely applied in tissue treatment as well as for heating of solid polymer materials. Previous studies investigating the heating effect in polymer materials utilized sound transmission through water or other fluids at low HIFU power. In this study, the ultrasonic transducer possesses a solid sound conductor made of aluminum and a high HIFU power of above 100W was applied to heat solid PE-LD samples. Temperature measurements were performed by calibrated non-invasive infrared thermal imaging. A strong heating effect with heating above melting temperature and evaporation temperature within less than 1s of irradiation was observed. Furthermore, the acoustic coupling defined by the force applied by the ultrasonic applicator to the polymer material was found to be fundamental to induce the heating effect. This investigation reveals HIFU for new applications in the field of polymer processing. PMID:27208613

  10. Whisker-reinforced heat-cured dental resin composites: effects of filler level and heat-cure temperature and time.

    PubMed

    Xu, H H

    2000-06-01

    Currently available dental resin composites are inadequate for use in large stress-bearing crown and multiple-unit restorations. The aim of this study was to reinforce heat-cured composites with ceramic whiskers. It was hypothesized that whiskers substantially strengthen heat-cured composites. It was further hypothesized that whisker filler level and heat-cure temperature and time significantly influence composite properties. Silica particles were fused onto the whiskers to facilitate silanization and to roughen the whiskers for improved retention in the matrix. The whisker filler mass fraction was varied from 0% to 79%, the heat-cure temperature from 80 degrees C to 180 degrees C, and cure time from 10 min to 24 hrs. Flexural strength, work-of-fracture, and fracture toughness of the composites were measured, and specimen fracture surfaces were examined with scanning electron microscopy. Filler level had a significant effect on composite properties. The whisker composite with 70% filler level had a flexural strength in MPa (mean +/- SD; n = 6) of 248 +/- 23, significantly higher than 120 +/- 16 of an inlay/onlay composite control and 123 +/- 21 of a prosthetic composite control (Tukey's multiple comparison test; family confidence coefficient = 0.95). Heat-cure time also played a significant role. At 120 degrees C, the strength of composite cured for 10 min was 178 +/- 17, lower than 236 +/- 14 of composite cured for 3 hrs. The strength of whisker composite did not degrade after water-aging for 100 d. In conclusion, heat-cured composites were substantially reinforced with whiskers. The reinforcement mechanisms appeared to be whiskers bridging and resisting cracks. The strength and fracture toughness of whisker composite were nearly twice those of currently available inlay/onlay and prosthetic composites.

  11. Artificial Neural Networks: a viable tool to design heat load smoothing strategies for the ITER Toroidal Field coils

    NASA Astrophysics Data System (ADS)

    Froio, A.; Bonifetto, R.; Carli, S.; Quartararo, A.; Savoldi, L.; Zanino, R.

    2015-12-01

    In superconducting tokamaks, cryoplants provide the helium needed to cool the superconducting magnet systems. The evaluation of the heat load from the magnets to the cryoplant is fundamental for the design of the latter and the assessment of suitable strategies to smooth the heat load pulses induced by the pulsed plasma scenarios is crucial for the operation. Here, a simplified thermal-hydraulic model of an ITER Toroidal Field (TF) magnet, based on Artificial Neural Networks (ANNs), is developed and inserted into a detailed model of the ITER TF winding and casing cooling circuits based on the state-of-the-art 4C code, which also includes active controls. The low computational effort requested by such a model allows performing a fast parametric study, to identify the best smoothing strategy during standard plasma operation. The ANNs are trained using 4C simulations, and the predictive capabilities of the simplified model are assessed against 4C simulations, both with and without active smoothing, in terms of accuracy and computational time.

  12. Heating-Rate-Triggered Carbon-Nanotube-based 3-Dimensional Conducting Networks for a Highly Sensitive Noncontact Sensing Device

    NASA Astrophysics Data System (ADS)

    Tai, Yanlong; Lubineau, Gilles

    2016-01-01

    Recently, flexible and transparent conductive films (TCFs) are drawing more attention for their central role in future applications of flexible electronics. Here, we report the controllable fabrication of TCFs for moisture-sensing applications based on heating-rate-triggered, 3-dimensional porous conducting networks through drop casting lithography of single-walled carbon nanotube (SWCNT)/poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate (PEDOT:PSS) ink. How ink formula and baking conditions influence the self-assembled microstructure of the TCFs is discussed. The sensor presents high-performance properties, including a reasonable sheet resistance (2.1 kohm/sq), a high visible-range transmittance (>69%, PET = 90%), and good stability when subjected to cyclic loading (>1000 cycles, better than indium tin oxide film) during processing, when formulation parameters are well optimized (weight ratio of SWCNT to PEDOT:PSS: 1:0.5, SWCNT concentration: 0.3 mg/ml, and heating rate: 36 °C/minute). Moreover, the benefits of these kinds of TCFs were verified through a fully transparent, highly sensitive, rapid response, noncontact moisture-sensing device (5 × 5 sensing pixels).

  13. Heating-Rate-Triggered Carbon-Nanotube-based 3-Dimensional Conducting Networks for a Highly Sensitive Noncontact Sensing Device

    PubMed Central

    Tai, Yanlong; Lubineau, Gilles

    2016-01-01

    Recently, flexible and transparent conductive films (TCFs) are drawing more attention for their central role in future applications of flexible electronics. Here, we report the controllable fabrication of TCFs for moisture-sensing applications based on heating-rate-triggered, 3-dimensional porous conducting networks through drop casting lithography of single-walled carbon nanotube (SWCNT)/poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate (PEDOT:PSS) ink. How ink formula and baking conditions influence the self-assembled microstructure of the TCFs is discussed. The sensor presents high-performance properties, including a reasonable sheet resistance (2.1 kohm/sq), a high visible-range transmittance (>69%, PET = 90%), and good stability when subjected to cyclic loading (>1000 cycles, better than indium tin oxide film) during processing, when formulation parameters are well optimized (weight ratio of SWCNT to PEDOT:PSS: 1:0.5, SWCNT concentration: 0.3 mg/ml, and heating rate: 36 °C/minute). Moreover, the benefits of these kinds of TCFs were verified through a fully transparent, highly sensitive, rapid response, noncontact moisture-sensing device (5 × 5 sensing pixels). PMID:26818091

  14. Chaotifying delayed recurrent neural networks via impulsive effects

    NASA Astrophysics Data System (ADS)

    Şaylı, Mustafa; Yılmaz, Enes

    2016-02-01

    In this paper, chaotification of delayed recurrent neural networks via chaotically changing moments of impulsive actions is considered. Sufficient conditions for the presence of Li-Yorke chaos with its ingredients proximality, frequent separation, and existence of infinitely many periodic solutions are theoretically proved. Finally, effectiveness of our theoretical results is illustrated by an example with numerical simulations.

  15. Children's Agricultural Safety Network: Evaluating Organizational Effectiveness and Impacts.

    PubMed

    Cramer, Mary E; Wendl, Mary J

    2015-01-01

    Coalitions that are effectively organized and led are more likely to achieve their intended program outcomes and impacts, as well as achieve sustainability. External evaluation of the coalition's governance and leadership can help identify strengths and areas for improvement. This article describes the evaluation of the Children's Agricultural Safety Network (CASN)-a national coalition, or network of 45 organizational members. The conceptual framework, Internal Coalition Outcomes Hierarchy, guided the evaluation. We used a mixed-methods approach to answer study's primary objectives from the perspective of CASN members and leaders for (a) organizational effectiveness, (b) network impact, and (c) member benefits. We collected quantitative data using a survey and the Internal Coalition Effectiveness (ICE) instrument. Focused interviews were conducted by phone to gather rich data on examples. Combined findings showed that both members and leaders rated the CASN effective in all construct areas that define successful coalitions. Members feel as invested in CASN success as do leaders. The major impact of CASN has been as a national leader and clearinghouse for childhood safety issues, and the most frequently cited example of impact was the national tractor safety campaign. Members identified the benefits of CASN membership as networking, resource sharing, and opportunities to enhance their knowledge, skills, and practices in the area. Members also valued the national attention that CASN was able to bring to the important issues in childhood agricultural safety. Suggestions for improvement were to focus on more research to improve best practices and strengthen dissemination and implementation science. PMID:25906269

  16. Children's Agricultural Safety Network: Evaluating Organizational Effectiveness and Impacts.

    PubMed

    Cramer, Mary E; Wendl, Mary J

    2015-01-01

    Coalitions that are effectively organized and led are more likely to achieve their intended program outcomes and impacts, as well as achieve sustainability. External evaluation of the coalition's governance and leadership can help identify strengths and areas for improvement. This article describes the evaluation of the Children's Agricultural Safety Network (CASN)-a national coalition, or network of 45 organizational members. The conceptual framework, Internal Coalition Outcomes Hierarchy, guided the evaluation. We used a mixed-methods approach to answer study's primary objectives from the perspective of CASN members and leaders for (a) organizational effectiveness, (b) network impact, and (c) member benefits. We collected quantitative data using a survey and the Internal Coalition Effectiveness (ICE) instrument. Focused interviews were conducted by phone to gather rich data on examples. Combined findings showed that both members and leaders rated the CASN effective in all construct areas that define successful coalitions. Members feel as invested in CASN success as do leaders. The major impact of CASN has been as a national leader and clearinghouse for childhood safety issues, and the most frequently cited example of impact was the national tractor safety campaign. Members identified the benefits of CASN membership as networking, resource sharing, and opportunities to enhance their knowledge, skills, and practices in the area. Members also valued the national attention that CASN was able to bring to the important issues in childhood agricultural safety. Suggestions for improvement were to focus on more research to improve best practices and strengthen dissemination and implementation science.

  17. Chaotifying delayed recurrent neural networks via impulsive effects.

    PubMed

    Şaylı, Mustafa; Yılmaz, Enes

    2016-02-01

    In this paper, chaotification of delayed recurrent neural networks via chaotically changing moments of impulsive actions is considered. Sufficient conditions for the presence of Li-Yorke chaos with its ingredients proximality, frequent separation, and existence of infinitely many periodic solutions are theoretically proved. Finally, effectiveness of our theoretical results is illustrated by an example with numerical simulations.

  18. The effect of direct heating and cooling of heat regulation centers on body temperature

    NASA Technical Reports Server (NTRS)

    Barbour, H. G.

    1978-01-01

    Experiments were done on 28 rabbits in which puncture instruments were left in the brain for 1-2 days until the calori-puncture hyperthermia had passed and the body temperature was again normal. The instrument remaining in the brain was then used as a galvanic electrode and a second fever was produced, this time due to the electrical stimulus. It was concluded that heat is a centrally acting antipyretic and that cold is a centrally acting stimulus which produces hyperpyrexia cold-induced fever.

  19. Urban Heat Island Growth Modeling Using Artificial Neural Networks and Support Vector Regression: A case study of Tehran, Iran

    NASA Astrophysics Data System (ADS)

    Sherafati, Sh. A.; Saradjian, M. R.; Niazmardi, S.

    2013-09-01

    Numerous investigations on Urban Heat Island (UHI) show that land cover change is the main factor of increasing Land Surface Temperature (LST) in urban areas. Therefore, to achieve a model which is able to simulate UHI growth, urban expansion should be concerned first. Considerable researches on urban expansion modeling have been done based on cellular automata. Accordingly the objective of this paper is to implement CA method for trend detection of Tehran UHI spatiotemporal growth based on urban sprawl parameters (such as Distance to nearest road, Digital Elevation Model (DEM), Slope and Aspect ratios). It should be mentioned that UHI growth modeling may have more complexities in comparison with urban expansion, since the amount of each pixel's temperature should be investigated instead of its state (urban and non-urban areas). The most challenging part of CA model is the definition of Transfer Rules. Here, two methods have used to find appropriate transfer Rules which are Artificial Neural Networks (ANN) and Support Vector Regression (SVR). The reason of choosing these approaches is that artificial neural networks and support vector regression have significant abilities to handle the complications of such a spatial analysis in comparison with other methods like Genetic or Swarm intelligence. In this paper, UHI change trend has discussed between 1984 and 2007. For this purpose, urban sprawl parameters in 1984 have calculated and added to the retrieved LST of this year. In order to achieve LST, Thematic Mapper (TM) and Enhanced Thematic Mapper (ETM+) night-time images have exploited. The reason of implementing night-time images is that UHI phenomenon is more obvious during night hours. After that multilayer feed-forward neural networks and support vector regression have used separately to find the relationship between this data and the retrieved LST in 2007. Since the transfer rules might not be the same in different regions, the satellite image of the city has

  20. Effect of the magnetic field direction on forced convection heat transfer enhancements in ferrofluids

    NASA Astrophysics Data System (ADS)

    Cherief, Wahid; Avenas, Yvan; Ferrouillat, Sébastien; Kedous-Lebouc, Afef; Jossic, Laurent; Berard, Jean; Petit, Mickael

    2015-07-01

    Applying a magnetic field on a ferrofluid flow induces a large increase of the convective heat transfer coefficient. In this paper, the thermal-hydraulic behaviors of two commercial ferrofluids are compared. The variations of both the pressure drop and the heat transfer coefficient due to the magnetic field are measured in the following conditions: square duct, laminar flow and uniform wall heat flux. The square section with two insulated walls allows for the characterization of the effect of the magnetic field direction. The experimental results show that the heat transfer is better enhanced when the magnetic field is perpendicular to the heat flux. In the best case, the local heat transfer coefficient increase is about 75%. On the contrary, another experimental setup shows no enhancement of thermal conductivity when the magnetic field is perpendicular to the heat flux. Contribution to the topical issue "Electrical Engineering Symposium (SGE 2014) - Elected submissions", edited by Adel Razek

  1. Alfven wave trapping, network microflaring, and heating in solar coronal holes

    NASA Technical Reports Server (NTRS)

    Moore, R. L.; Suess, S. T.; Musielak, Z. E.; An, C.-H.

    1991-01-01

    Fresh evidence that much of the heating in coronal holes is provided by Alfven waves is presented. This evidence comes from examining the reflection of Alfven waves in an isothermal hydrostatic model coronal hole with an open magnetic field. Reflection occurs if the wavelength is as long as the order of the scale height of the Alfven velocity. For Alfven waves with periods of about 5 min, and for realistic density, magnetic field strength, and magnetic field spreading in the model, the waves are reflected back down within the model hole if the coronal temperature is only slightly less than 1.0 x 10 to the 6th K, but are not reflected and escape out the top of the model if the coronal temperature is only slightly greater than 1.0 x 10 to the 6th K. Because the spectrum of Alfven waves in real coronal holes is expected to peak around 5 min and the temperature is observed to be close to 1.0 x 10 to the 6th K, the sensitive temperature dependence of the trapping suggests that the temperature in coronal holes is regulated by heating by the trapped Alfven waves.

  2. The effect of music-induced mood on attentional networks.

    PubMed

    Jiang, Jun; Scolaro, Ashley J; Bailey, Kira; Chen, Antao

    2011-06-01

    Attention network theory suggests that there are three separate neural networks that execute the discrete functions of alerting, orienting, and executive attention. Previous research on the influence of mood on attention has shown subtle and inconsistent results. The attention network theory may aid in clarifying the influence of mood on attention. The present study investigated the influence of mood on attentional networks in a normal population. Participants performed the Attention Network Test (ANT), which provides functional measures of alerting, orienting, and executive attention. Positive or negative mood was induced by listening to music with a positive or negative valence, respectively; neutral mood was induced by reading a collection of basic facts about China. The results revealed that negative mood led to a significantly higher alerting efficiency relative to other moods, while there were no significant mood effects on orienting or executive attention efficiency. According to the algorithm underlying the ANT, the higher alerting efficiency in the negative mood condition can be attributed to relatively greater benefits of cueing effects. The findings are discussed in the context of the noradrenergic system and of evolutionary significance. Specifically, the increase in the alerting function during negative mood states may be due to the modulation effect of negative mood on the noradrenergic system, and/or to the survival benefit resulting from an increase in automatic vigilance towards negative information. The current results suggest that as the influence of negative mood on attention appears to specifically consist in an enhanced alerting function, it may not be found in studies where the three attentional networks are not dissociated.

  3. Environmental microbiology as related to planetary quarantine. [synergetic effect of heat and radiation

    NASA Technical Reports Server (NTRS)

    Pflug, I. J.

    1973-01-01

    The mechanistic basis of the synergetic effect of combined heat and radiation on microbial destruction was analyzed and results show that radiation intensity, temperature, and relative humidity are the determining factors. Dry heat resistance evaluation for selected bacterial spore crops indicates that different strains of Bacillus stearothermophilus demonstrate marked differences in resistance. Preliminary work to determine the effects of storage time, suspending medium, storage temperature and spore crop cleaning procedures on dry heat survival characteristics of Bacillus subtilis var. Niger, and dry heat resistance of natural microflora in soil particles is also reported.

  4. Effect of nanoparticles on critical heat flux of water in pool boiling heat transfer

    NASA Astrophysics Data System (ADS)

    You, S. M.; Kim, J. H.; Kim, K. H.

    2003-10-01

    The present study is to enhance the critical heat flux (CHF) in pool boiling from a flat square heater immersed in nanofluid (water mixed with extremely small amount of nanosized particles). The test results show that the enhancement of CHF was drastic when nanofluid is used as a cooling liquid instead of pure water. The experiment was performed to measure and compare pool boiling curves of pure water and nanofluid at the pressure of 2.89 psia (Tsat=60 °C) using 1×1 cm2 polished copper surfaces as a boiling surface. The tested nanofluid contains alumina (Al2O3) nanoparticles dispersed in distilled and deionized water. Tested concentrations of nanoparticles range from 0 g/l to 0.05 g/l. The measured pool boiling curves of nanofluids saturated at 60 °C have demonstrated that the CHF increases dramatically (˜200% increase) compared to pure water case; however, the nucleate boiling heat transfer coefficients appear to be about the same.

  5. Gravity and Heater Size Effects on Pool Boiling Heat Transfer

    NASA Technical Reports Server (NTRS)

    Kim, Jungho; Raj, Rishi

    2014-01-01

    The current work is based on observations of boiling heat transfer over a continuous range of gravity levels between 0g to 1.8g and varying heater sizes with a fluorinert as the test liquid (FC-72/n-perfluorohexane). Variable gravity pool boiling heat transfer measurements over a wide range of gravity levels were made during parabolic flight campaigns as well as onboard the International Space Station. For large heaters and-or higher gravity conditions, buoyancy dominated boiling and heat transfer results were heater size independent. The power law coefficient for gravity in the heat transfer equation was found to be a function of wall temperature under these conditions. Under low gravity conditions and-or for smaller heaters, surface tension forces dominated and heat transfer results were heater size dependent. A pool boiling regime map differentiating buoyancy and surface tension dominated regimes was developed along with a unified framework that allowed for scaling of pool boiling over a wide range of gravity levels and heater sizes. The scaling laws developed in this study are expected to allow performance quantification of phase change based technologies under variable gravity environments eventually leading to their implementation in space based applications.

  6. Effects of simulated heat waves on cardiovascular functions in senile mice.

    PubMed

    Zhang, Xiakun; Lu, Jing; Zhang, Shuyu; Wang, Chunling; Wang, Baojian; Guo, Pinwen; Dong, Lina

    2014-08-01

    The mechanism of the effects of simulated heat waves on cardiovascular disease in senile mice was investigated. Heat waves were simulated in a TEM1880 meteorological environment simulation chamber, according to a heat wave that occurred in July 2001 in Nanjing, China. Eighteen senile mice were divided into control, heat wave, and heat wave BH4 groups, respectively. Mice in the heat wave and heat wave BH4 groups were exposed to simulated heat waves in the simulation chamber. The levels of ET-1, NO, HSP60, SOD, TNF, sICAM-1, and HIF-1α in each group of mice were measured after heat wave simulation. Results show that heat waves decreased SOD activity in the myocardial tissue of senile mice, increased NO, HSP60, TNF, sICAM-1, and HIF-1α levels, and slightly decreased ET-1 levels, BH4 can relieve the effects of heat waves on various biological indicators. After a comprehensive analysis of the experiments above, we draw the followings conclusions regarding the influence of heat waves on senile mice: excess HSP60 activated immune cells, and induced endothelial cells and macrophages to secrete large amounts of ICAM-1, TNF-α, and other inflammatory cytokines, it also activated the inflammation response in the body and damaged the coronary endothelial cell structure, which increased the permeability of blood vessel intima and decreased SOD activity in cardiac tissues. The oxidation of lipoproteins in the blood increased, and large amounts of cholesterol were generated. Cholesterol penetrated the intima and deposited on the blood vessel wall, forming atherosclerosis and leading to the occurrence of cardiovascular disease in senile mice. These results maybe are useful for studying the effects of heat waves on elderly humans, which we discussed in the discussion chapter. PMID:25101768

  7. Effect of homogenization heat treatment on the microstructure and heat- affected zone microfissuring in welded cast alloy 718

    NASA Astrophysics Data System (ADS)

    Huang, Xiao; Chaturvedi, M. C.; Richards, N. L.

    1996-03-01

    The effect of homogenization temperature on microfissuring in the heat-affected zones of electronwelded cast INCONEL 718 has been studied. The material was homogenized at various temperatures in the range of 1037 ° to 1163 ° and air-cooled. The homogenized material was then electron-beam welded by the bead-on-plate welding technique. The microstructures and microfissuring in the heat-affected zone (HAZ) were evaluated by analytical scanning electron microscopy (SEM). The grain boundary segregation of various elements was evaluated by secondary ion mass spectroscopy (SIMS). It was observed that the total crack length (TCL) of microfissures first decreases with homogenization temperature and then increases, with a minimum occurring in the specimen heat treated at 1163 °. This trend coincides with the variation in segregation of B at grain boundaries with homogenization temperature and has been explained by equilibrium and nonequilibrium segregation of B to grain boundaries during the homogenization heat treatment. No other element was observed to segregate at the grain boundaries. The variation in volume fraction of phases like δ-Ni3Nb, MC carbide, and Laves phases does not follow the same trend as that observed for TCL and B segregation at the grain boundaries. Therefore, microfissuring in HAZ of welded cast INCONEL 718 is attributed to the segregation of B at the grain boundaries.

  8. Effect of crystallization heat treatment on the microstructure of niobium-doped fluorapatite glass-ceramics.

    PubMed

    Denry, I; Holloway, J A; Gupta, P K

    2012-07-01

    Our goal was to study the effect of heat treatment temperature and heating rate on the microstructure and crystalline phases and assess the domain of existence of submicrometer fluorapatite crystals in niobium-doped fluorapatite glass-ceramics for biomedical applications. Glass-ceramic specimens were prepared by casting and heat treatment between 700 and 1200°C using a fast or a slow heating rate. The microstructure was characterized by atomic force microscopy and scanning electron microscopy. Crystalline phases were analyzed by x-ray diffraction. AFM of the as-cast glass revealed that amorphous phase separation occurred in this system. XRD confirmed the presence of fluorapatite in all specimens, together with forsterite and enstatite at higher temperatures. Both heating rate and heat treatment temperature strongly influenced microstructure and crystallinity. A dual microstructure with submicrometer fluorapatite crystals and polygonal forsterite crystals was obtained when slow heating rates and crystallization temperatures between 950 and 1100°C were used. Needle-shaped fluorapatite crystals appeared after heat treatment above 1100°C. Fast heating rates led to an increase in crystal size. Heat treatment temperatures should remain below 1100°C, together with slow heating rates, to prevent crystal dissolution, and preserve a dual microstructure of finely dispersed submicrometer crystals without growth of needle-shaped crystals.

  9. Effect of crystallization heat treatment on the microstructure of niobium-doped fluorapatite glass-ceramics

    PubMed Central

    Denry, I.; Holloway, J.A.; Gupta, P.K.

    2012-01-01

    Our goal was to study the effect of heat treatment temperature and heating rate on the microstructure and crystalline phases and assess the domain of existence of sub-micrometer fluorapatite crystals in niobium-doped fluorapatite glass-ceramics for biomedical applications. Glass-ceramic specimens were prepared by casting and heat treatment between 700 and 1200°C using a fast or a slow heating rate. The microstructure was characterized by atomic force microscopy and scanning electron microscopy. Crystalline phases were analyzed by x-ray diffraction. AFM of the as-cast glass revealed that amorphous phase separation occurred in this system. XRD confirmed the presence of fluorapatite in all specimens, together with forsterite and enstatite at higher temperatures. Both heating rate and heat treatment temperature strongly influenced microstructure and crystallinity. A dual microstructure with sub-micrometer fluorapatite crystals and polygonal forsterite crystals was obtained when slow heating rates and crystallization temperatures between 950 and 1100°C were used. Needle-shaped fluorapatite crystals appeared after heat treatment above 1100°C. Fast heating rates led to an increase in crystal size. Heat treatment temperatures should remain below 1100°C, together with slow heating rates, to prevent crystal dissolution, and preserve a dual microstructure of finely dispersed sub-micrometer crystals without growth of needle-shaped crystals. PMID:22454333

  10. Effects of ventilation behaviour on indoor heat load based on test reference years

    NASA Astrophysics Data System (ADS)

    Rosenfelder, Madeleine; Koppe, Christina; Pfafferott, Jens; Matzarakis, Andreas

    2016-02-01

    Since 2003, most European countries established heat health warning systems to alert the population to heat load. Heat health warning systems are based on predicted meteorological conditions outdoors. But the majority of the European population spends a substantial amount of time indoors, and indoor thermal conditions can differ substantially from outdoor conditions. The German Meteorological Service (Deutscher Wetterdienst, DWD) extended the existing heat health warning system (HHWS) with a thermal building simulation model to consider heat load indoors. In this study, the thermal building simulation model is used to simulate a standardized building representing a modern nursing home, because elderly and sick people are most sensitive to heat stress. Different types of natural ventilation were simulated. Based on current and future test reference years, changes in the future heat load indoors were analyzed. Results show differences between the various ventilation options and the possibility to minimize the thermal heat stress during summer by using an appropriate ventilation method. Nighttime ventilation for indoor thermal comfort is most important. A fully opened window at nighttime and the 2-h ventilation in the morning and evening are more sufficient to avoid heat stress than a tilted window at nighttime and the 1-h ventilation in the morning and the evening. Especially the ventilation in the morning seems to be effective to keep the heat load indoors low. Comparing the results for the current and the future test reference years, an increase of heat stress on all ventilation types can be recognized.

  11. Control of epidemics on complex networks: Effectiveness of delayed isolation

    NASA Astrophysics Data System (ADS)

    Pereira, Tiago; Young, Lai-Sang

    2015-08-01

    We study isolation as a means to control epidemic outbreaks in complex networks, focusing on the consequences of delays in isolating infected nodes. Our analysis uncovers a tipping point: if infected nodes are isolated before a critical day dc, the disease is effectively controlled, whereas for longer delays the number of infected nodes climbs steeply. We show that dc can be estimated explicitly in terms of network properties and disease parameters, connecting lowered values of dc explicitly to heterogeneity in degree distribution. Our results reveal also that initial delays in the implementation of isolation protocols can have catastrophic consequences in heterogeneous networks. As our study is carried out in a general framework, it has the potential to offer insight and suggest proactive strategies for containing outbreaks of a range of serious infectious diseases.

  12. Control of epidemics on complex networks: Effectiveness of delayed isolation.

    PubMed

    Pereira, Tiago; Young, Lai-Sang

    2015-08-01

    We study isolation as a means to control epidemic outbreaks in complex networks, focusing on the consequences of delays in isolating infected nodes. Our analysis uncovers a tipping point: if infected nodes are isolated before a critical day dc, the disease is effectively controlled, whereas for longer delays the number of infected nodes climbs steeply. We show that dc can be estimated explicitly in terms of network properties and disease parameters, connecting lowered values of dc explicitly to heterogeneity in degree distribution. Our results reveal also that initial delays in the implementation of isolation protocols can have catastrophic consequences in heterogeneous networks. As our study is carried out in a general framework, it has the potential to offer insight and suggest proactive strategies for containing outbreaks of a range of serious infectious diseases. PMID:26382469

  13. On effectiveness of network sensor-based defense framework

    NASA Astrophysics Data System (ADS)

    Zhang, Difan; Zhang, Hanlin; Ge, Linqiang; Yu, Wei; Lu, Chao; Chen, Genshe; Pham, Khanh

    2012-06-01

    Cyber attacks are increasing in frequency, impact, and complexity, which demonstrate extensive network vulnerabilities with the potential for serious damage. Defending against cyber attacks calls for the distributed collaborative monitoring, detection, and mitigation. To this end, we develop a network sensor-based defense framework, with the aim of handling network security awareness, mitigation, and prediction. We implement the prototypical system and show its effectiveness on detecting known attacks, such as port-scanning and distributed denial-of-service (DDoS). Based on this framework, we also implement the statistical-based detection and sequential testing-based detection techniques and compare their respective detection performance. The future implementation of defensive algorithms can be provisioned in our proposed framework for combating cyber attacks.

  14. HEATING OF THE MAGNETIZED SOLAR CHROMOSPHERE BY PARTIAL IONIZATION EFFECTS

    SciTech Connect

    Khomenko, E.; Collados, M.

    2012-03-10

    In this paper, we study the heating of the magnetized solar chromosphere induced by the large fraction of neutral atoms present in this layer. The presence of neutrals, together with the decrease with height of the collisional coupling, leads to deviations from the classical magnetohydrodynamic behavior of the chromospheric plasma. A relative net motion appears between the neutral and ionized components, usually referred to as ambipolar diffusion. The dissipation of currents in the chromosphere is enhanced by orders of magnitude due to the action of ambipolar diffusion, as compared with the standard ohmic diffusion. We propose that a significant amount of magnetic energy can be released to the chromosphere just by existing force-free 10-40 G magnetic fields there. As a consequence, we conclude that ambipolar diffusion is an important process that should be included in chromospheric heating models, as it has the potential to rapidly heat the chromosphere. We perform analytical estimations and numerical simulations to prove this idea.

  15. Effect of heat treatment temperature on nitinol wire

    SciTech Connect

    Cai, S.; Schaffer, J. E.; Daymond, M. R.; Yu, C.; Ren, Y.

    2014-08-18

    In-situ synchrotron X-ray diffraction has been used to study the influence of the heat treatment temperature on the subsequent micromechanical behavior of nitinol wire. It was found that increase in the heat treatment temperature rotated the austenite texture from the (332){sub B2} fiber towards the (111){sub B2} fiber, and the texture of the Stress-Induced Martensite phase changed from the (1{sup ¯}40){sub B19'} to the (1{sup ¯}20){sub B19'} fiber accordingly. Heat treatment at a low temperature reduces the internal residual strains in the austenite during super-elastic deformation and therefore improves the materials fatigue performance. The development of internal residual strains in austenite is controlled by transformation induced plasticity and the reversal martensite to austenite transformation.

  16. High effectiveness liquid droplet/gas heat exchanger for space power applications

    NASA Technical Reports Server (NTRS)

    Bruckner, A. P.; Mattick, A. T.

    1983-01-01

    A high-effectiveness liquid droplet/gas heat exchanger (LDHX) concept for thermal management in space is described. Heat is transferred by direct contact between fine droplets (approx. 100 to 300 micron diameter) of a suitable low vapor pressure liquid and an inert working gas. Complete separation of the droplet and gas media in the zero-g environment is accomplished by configuring the LDHX as a vortex chamber. The large heat transfer area presented by the small droplets permits heat exchanger effectiveness of 0.9 to 0.95 in a compact, lightweight geometry which avoids many of the limitations of conventional plate and fin or tube and shell heat exchangers, such as their tendency toward single point failure. The application of the LDHX in a high temperature Bryaton cycle is discussed to illustrate the performance and operational characteristics of this heat exchanger concept.

  17. High effectiveness liquid droplet/gas heat exchanger for space power applications

    NASA Technical Reports Server (NTRS)

    Bruckner, A. P.; Mattick, A. T.

    1983-01-01

    A high-effectiveness liquid droplet/gas heat exchanger (LDHX) concept for thermal management in space is described. Heat is transferred by direct contact between fine droplets (approximately 100-300 microns in diameter) of a suitable low vapor pressure liquid and an inert working gas. Complete separation of the droplet and gas media in the zero-g environment is accomplished by configuring the LDHX as a vortex chamber.The large heat transfer area presented by the small droplets permits heat exchanger effectiveness of 0.9-0.95 in a compact, lightweight geometry which avoids many of the limitations of conventional plate and fin or tube and shell heat exchangers, such as their tendency toward single point failure. The application of the LDHX in a high temperature Brayton cycle is discussed to illustrate the performance and operational characteristics of this new heat exchanger concept.

  18. The effect of heat treatment of wood on osteoconductivity.

    PubMed

    Rekola, J; Aho, A J; Gunn, J; Matinlinna, J; Hirvonen, J; Viitaniemi, P; Vallittu, P K

    2009-06-01

    Wood is a natural porous fibre composite, which has some structural similarities to bone. Recently, it has been used as a modelling material in developing synthetic fibre-reinforced composite to be used as load-bearing non-metallic artificial bone material. In this study, the behaviour of wood implanted into bone was studied in vivo in the femur bone of the rabbit. Wood was pre-treated by heat, which altered its chemical composition and structure, as well as the biomechanical properties. In the heat treatment, wood's dimensional stability is enhanced, equilibrium moisture content reduces and the biological durability increases. Cone-shaped implants were manufactured from heat-treated (at 200 and 140 degrees C) birch wood (Betula pubescens) and from untreated birch. A total of 62 implants were placed in the distal femur of 50 white New Zealand rabbits. The behaviour of the implants was studied at 4, 8 and 20 weeks with histological and histometrical analysis. Osteoconductive contact line and the presence of fibrous tissue and foreign body reaction were determined. The amount of fibrous tissue diminished with time, and the absence of foreign body reaction was found to be in correlation to the amount of heat treatment. Histologically found contact between the implant and the host bone at the interface was significantly more abundant in the 200 degrees C group (avg. 12.8%) vs. the 140 degrees C (avg. 2.7%) and the untreated groups (avg. 0.6%). It was observed that the heat treatment significantly modified the biological behaviour of the implanted wood. The changes of the wood by heat treatment showed a positive outcome concerning osteoconductivity of the material.

  19. SEAC4RS Aerosol Radiative Effects and Heating Rates

    NASA Astrophysics Data System (ADS)

    Cochrane, S.; Schmidt, S.; Redemann, J.; Hair, J. W.; Ferrare, R. A.; Segal-Rosenhaimer, M.; LeBlanc, S. E.

    2015-12-01

    We will present (a) aerosol optical properties, (b) aerosol radiative forcing, (c) aerosol and gas absorption and heating rates, and (d) spectral surface albedo for cases from August 19th and 26th of the SEAC4RS mission. This analysis is based on irradiance data from the Solar Spectral Flux Radiometer (SSFR), spectral aerosol optical depth from the Sky-Scanning, Sun-Tracking Atmospheric Research (4STAR), and extinction profiles from the DIAL/High Spectral Resolution Lidar (HSRL). We derive spectrally resolved values of single scattering albedo, asymmetry parameter, and surface albedo from the data, and determine profiles of absorption and heating rate segregated by absorber (aerosol and gas).

  20. Effective Utilization of Commercial Wireless Networking Technology in Planetary Environments

    NASA Technical Reports Server (NTRS)

    Caulev, Michael (Technical Monitor); Phillip, DeLeon; Horan, Stephen; Borah, Deva; Lyman, Ray

    2005-01-01

    The purpose of this research is to investigate the use of commercial, off-the-shelf wireless networking technology in planetary exploration applications involving rovers and sensor webs. The three objectives of this research project are to: 1) simulate the radio frequency environment of proposed landing sites on Mars using actual topographic data, 2) analyze the performance of current wireless networking standards in the simulated radio frequency environment, and 3) propose modifications to the standards for more efficient utilization. In this annual report, we present our results for the second year of research. During this year, the effort has focussed on the second objective of analyzing the performance of the IEEE 802.11a and IEEE 802.1lb wireless networking standards in the simulated radio frequency environment of Mars. The approach builds upon our previous results which deterministically modelled the RF environment at selected sites on Mars using high-resolution topographical data. These results provide critical information regarding antenna coverage patterns, maximum link distances, effects of surface clutter, and multipath effects. Using these previous results, the physical layer of these wireless networking standards has now been simulated and analyzed in the Martian environment. We are looking to extending these results to the and medium access layer next. Our results give us critical information regarding the performance (data rates, packet error rates, link distances, etc.) of IEEE 802.1 la/b wireless networks. This information enables a critical examination of how these wireless networks may be utilized in future Mars missions and how they may be possibly modified for more optimal usage.

  1. Fossil Fuel and Biomass Burning Effect on Climate--Heating or Cooling?.

    NASA Astrophysics Data System (ADS)

    Kaufman, Yoram J.; Fraser, Robert S.; Mahoney, Robert L.

    1991-06-01

    Emission from burning of fossil fuels and biomass (associated with deforestation) generates a radiative forcing on the atmosphere and a possible climate chaw. Emitted trace gases heat the atmosphere through their greenhouse effect, while particulates formed from emitted SO2 cause cooling by increasing cloud albedos through alteration of droplet size distributions. This paper reviews the characteristics of the cooling effect and applies Twomey's theory to cheek whether the radiative balance favors heating or cooling for the cases of fossil fuel and biomass burning. It is also shown that although coal and oil emit 120 times as many CO2 molecules as SO2 molecules, each SO2 molecule is 50-1100 times more effective in cooling the atmosphere (through the effect of aerosol particles on cloud albedo) than a CO2 molecule is in heating it. Note that this ratio accounts for the large difference in the aerosol (3-10 days) and CO2 (7-100 years) lifetimes. It is concluded, that the cooling effect from coal and oil burning may presently range from 0.4 to 8 times the heating effect. Within this large uncertainty, it is presently more likely that fossil fuel burning causes cooling of the atmosphere rather than heating. Biomass burning associated with deforestation, on the other hand, is more likely to cause heating of the atmosphere than cooling since its aerosol cooling effect is only half that from fossil fuel burning and its heating effect is twice as large. Future increases in coal and oil burning, and the resultant increase in concentration of cloud condensation nuclei, may saturate the cooling effect, allowing the heating effect to dominate. For a doubling in the C02 concentration due to fossil fuel burning, the cooling effect is expected to be 0.1 to 0.3 of the heating effect.

  2. EFFECT OF HEATING RATE ON THE THERMODYNAMIC PROPERTIES OF PULVERIZED COAL

    SciTech Connect

    Ramanathan Sampath

    2000-01-01

    This final technical report describes work performed under DOE Grant No. DE-FG22-96PC96224 during the period September 24, 1996 to September 23, 1999 which covers the entire performance period of the project. During this period, modification, alignment, and calibration of the measurement system, measurement of devolatilization time-scales for single coal particles subjected to a range of heating rates and temperature data at these time-scales, and analysis of the temperature data to understand the effect of heating rates on coal thermal properties were carried out. A new thermodynamic model was developed to predict the heat transfer behavior for single coal particles using one approach based on the analogy for thermal property of polymers. Results of this model suggest that bituminous coal particles behave like polymers during rapid heating on the order of 10{sup 4}-10{sup 5} K/s. At these heating rates during the early stages of heating, the vibrational part of the heat capacity of the coal molecules appears to be still frozen but during the transition from heat-up to devolatilization, the heat capacity appears to attain a sudden jump in its value as in the case of polymers. There are a few data available in the coal literature for low heating rate experiments (10{sup 2}-10{sup 3} K/s) conducted by UTRC, our industrial partner, in this project. These data were obtained for a longer heating duration on the order of several seconds as opposed to the 10 milliseconds heating time of the single particle experiments discussed above. The polymer analogy model was modified to include longer heating time on the order of several seconds to test these data. However, the model failed to predict these low heating rate data. It should be noted that UTRC's work showed reasonably good agreement with Merrick model heat capacity predictions at these low heating rates, but at higher heating rates UTRC observed that coal thermal response was heat flux dependent. It is concluded that

  3. The critical role of aerodynamic heating effects in the design of hypersonic vehicles

    NASA Technical Reports Server (NTRS)

    Wieting, Allan R.

    1989-01-01

    Hypersonic vehicles operate in a hostile aerothermal environment, which has a significant impact on their aerothermostructural performance. Significant coupling occurs between the aerodynamic flow field, structural heat transfer, and structural response, creating a multidisciplinary interaction. The critical role of aerodynamic heating effects in the design of hypersonic vehicles is identified with an example of high localized heating on an engine-cowl leading edge. Recent advances is integrated fluid-thermal-structural finite-element analyses are presented.

  4. Effect of short-term exercise-heat acclimation on ventilatory and cerebral blood flow responses to passive heating at rest in humans.

    PubMed

    Fujii, Naoto; Tsuji, Bun; Honda, Yasushi; Kondo, Narihiko; Nishiyasu, Takeshi

    2015-09-01

    Hyperthermia induces hyperventilation and cerebral hypoperfusion in resting humans. We tested the hypothesis that short-term exercise-heat acclimation would alleviate those effects. Twenty healthy male subjects were divided into two groups that performed exercise training in the heat (TR-HEAT, n = 10) or cold (TR-COLD, n = 10). Before and after the training, the subjects in both groups participated in passive-heat tests at rest. Training was performed at 37°C (TR-HEAT) or 10°C (TR-COLD) and entailed four 20-min bouts of cycling at 50% peak oxygen uptake separated by 10-min recoveries daily for 6 consecutive days. After TR-HEAT, esophageal temperature was lowered when measured before and during passive heating, as was the esophageal temperature threshold for cutaneous active vasodilation, whereas plasma volume was increased (all P < 0.05). These traditional indices of successful heat acclimation were not all induced by TR-COLD (all P > 0.05). TR-HEAT had no significant effect on passive heating-induced increases in minute ventilation, even when evaluated as the esophageal temperature threshold for increases in minute ventilation and the slope relating minute ventilation to esophageal temperature (all P > 0.05). By contrast, TR-HEAT attenuated the passive heating-induced reduction in the cerebral vascular conductance index (middle cerebral artery mean blood velocity/mean arterial pressure) (all P < 0.05). TR-COLD did not attenuate the increase in minute ventilation or the decrease in the cerebral vascular conductance index observed during passive heating (all P > 0.05). These data suggest that in resting heated humans, short-term heat acclimation achieved through moderate-intensity exercise training (i.e., 50% peak oxygen uptake) in the heat does not influence hyperthermia-induced hyperventilation, but it does potentially attenuate cerebral hypoperfusion.

  5. Effect of thermal manipulation during embryogenesis on liver heat shock protein expression in chronic heat stressed colored broiler chickens.

    PubMed

    Vinoth, A; Thirunalasundari, T; Tharian, Jenny Anne; Shanmugam, M; Rajkumar, U

    2015-10-01

    Thermal manipulation during embryogenesis has been shown to improve thermo tolerance in broilers. Heat shock proteins are a family of proteins produced in response to variety of stress and protect cells from damage. The aim of this study was to evaluate the effect of thermal manipulation (TM) during embryogenesis on HSP gene and protein expression in the embryos and in chronic heat stressed 42nd day old chicks. On 15th day of incubation, fertile eggs from two breeds-Naked neck (NN) and Punjab Broiler-2 (PB-2) were randomly divided in to two groups, namely Control (C) eggs were incubated under standard incubation conditions and Thermal Conditioning (TC) eggs were exposed to higher incubation temperature (40.5°C) for 3h on 15th, 16th and 17th day of incubation. The chicks so obtained from each group were further subdivided and reared from 15th-42nd day as normal (N; 25±1°C, 70% RH) and heat exposed (HE; 35±1°C, 50% RH) resulting in four treatment groups (CN, CHE, TCN and TCHE). Embryos of two groups (C and TC) on 17th day and birds from four treatment groups on 42nd day were sacrificed. Liver was collected for analysis of gene expression by real-time PCR and protein expression by Western blot of Heat Shock Proteins (HSP 90 alpha, HSP 90 beta, HSP 70, HSP 60, HSP 27 and ubiquitin). The plasma collected on 42nd day was analyzed for biochemical parameters. Thermal challenging of embryos of both the breeds caused significant (P≤0.05) increase in all the HSPs gene and protein expression. The TCHE chicks had significantly (P≤0.05) lower HSPs gene and protein expressions and oxidative stress compared to CHE groups in both NN and PB-2. Based on these findings it can be concluded that TM during incubation provides adaptation to broiler chicks during chronic heat stress. PMID:26590469

  6. High Reynolds number and turbulence effects on aerodynamics and heat transfer in a turbine cascade

    NASA Technical Reports Server (NTRS)

    Yeh, Frederick C.; Hippensteele, Steven A.; Vanfossen, G. James; Poinsatte, Philip E.; Ameri, Ali

    1993-01-01

    Experimental data on pressure distribution and heat transfer on a turbine airfoil were obtained over a range of Reynolds numbers from 0.75 to 7.5 x 10 exp 6 and a range of turbulence intensities from 1.8 to about 15 percent. The purpose of this study was to obtain fundamental heat transfer and pressure distribution data over a wide range of high Reynolds numbers and to extend the heat transfer data base to include the range of Reynolds numbers encountered in the Space Shuttle main engine (SSME) turbopump turbines. Specifically, the study aimed to determine (1) the effect of Reynolds number on heat transfer, (2) the effect of upstream turbulence on heat transfer and pressure distribution, and (3) the relationship between heat transfer at high Reynolds numbers and the current data base. The results of this study indicated that Reynolds number and turbulence intensity have a large effect on both the transition from laminar to turbulent flow and the resulting heat transfer. For a given turbulence intensity, heat transfer for all Reynolds numbers at the leading edge can be correlated with the Frossling number developed for lower Reynolds numbers. For a given turbulence intensity, heat transfer for the airfoil surfaces downstream of the leading edge can be approximately correlated with a dimensionless parameter. Comparison of the experimental results were also made with a numerical solution from a two-dimensional Navier-Stokes code.

  7. The dilemma of hyperbolic heat conduction and its settlement by incorporating spatially nonlocal effect at nanoscale

    NASA Astrophysics Data System (ADS)

    Yu, Y. Jun; Li, Chen-Lin; Xue, Zhang-Na; Tian, Xiao-Geng

    2016-01-01

    To model transiently thermal responses of numerous thermal shock issues at nano-scale, Fourier heat conduction law is commonly extended by introducing time rate of heat flux, and comes to hyperbolic heat conduction (HHC). However, solution to HHC under Dirichlet boundary condition depicts abnormal phenomena, e.g. heat conducts from the cold to the hot, and there are two temperatures at one location. In this paper, HHC model is further perfected with the aids of spatially nonlocal effect, and the exceeding temperature as well as the discontinuity at the wave front are avoided. The effect of nonlocal parameter on temperature response is discussed. From the analysis, the importance of size effect for nano-scale heat conduction is emphasized, indicating that spatial and temporal extensions should be simultaneously made to nano-scale heat conduction. Beyond that, it is found that heat flux boundary conditions should be directly given, instead of Neumann boundary condition, which does not make sense any longer for non-classical heat conductive models. And finally, it is observed that accurate solution to such problems may be obtained using Laplace transform method, especially for the time-dependent boundary conditions, e.g. heat flux boundary condition.

  8. Effects of chemical bonding on heat transport across interfaces.

    PubMed

    Losego, Mark D; Grady, Martha E; Sottos, Nancy R; Cahill, David G; Braun, Paul V

    2012-04-22

    Interfaces often dictate heat flow in micro- and nanostructured systems. However, despite the growing importance of thermal management in micro- and nanoscale devices, a unified understanding of the atomic-scale structural features contributing to interfacial heat transport does not exist. Herein, we experimentally demonstrate a link between interfacial bonding character and thermal conductance at the atomic level. Our experimental system consists of a gold film transfer-printed to a self-assembled monolayer (SAM) with systematically varied termination chemistries. Using a combination of ultrafast pump-probe techniques (time-domain thermoreflectance, TDTR, and picosecond acoustics) and laser spallation experiments, we independently measure and correlate changes in bonding strength and heat flow at the gold-SAM interface. For example, we experimentally demonstrate that varying the density of covalent bonds within this single bonding layer modulates both interfacial stiffness and interfacial thermal conductance. We believe that this experimental system will enable future quantification of other interfacial phenomena and will be a critical tool to stimulate and validate new theories describing the mechanisms of interfacial heat transport. Ultimately, these findings will impact applications, including thermoelectric energy harvesting, microelectronics cooling, and spatial targeting for hyperthermal therapeutics.

  9. Mach number effect on jet impingement heat transfer.

    PubMed

    Brevet, P; Dorignac, E; Vullierme, J J

    2001-05-01

    An experimental investigation of heat transfer from a single round free jet, impinging normally on a flat plate is described. Flow at the exit plane of the jet is fully developed and the total temperature of the jet is equal to the ambient temperature. Infrared measurements lead to the characterization of the local and averaged heat transfer coefficients and Nusselt numbers over the impingement plate. The adiabatic wall temperature is introduced as the reference temperature for heat transfer coefficient calculation. Various nozzle diameters from 3 mm to 15 mm are used to make the injection Mach number M vary whereas the Reynolds number Re is kept constant. Thus the Mach number influence on jet impingement heat transfer can be directly evaluated. Experiments have been carried out for 4 nozzle diameters, for 3 different nozzle-to-target distances, with Reynolds number ranging from 7200 to 71,500 and Mach number from 0.02 to 0.69. A correlation is obtained from the data for the average Nusselt number. PMID:11460655

  10. Effect of foam on temperature prediction and heat recovery potential from biological wastewater treatment.

    PubMed

    Corbala-Robles, L; Volcke, E I P; Samijn, A; Ronsse, F; Pieters, J G

    2016-05-15

    Heat is an important resource in wastewater treatment plants (WWTPs) which can be recovered. A prerequisite to determine the theoretical heat recovery potential is an accurate heat balance model for temperature prediction. The insulating effect of foam present on the basin surface and its influence on temperature prediction were assessed in this study. Experiments were carried out to characterize the foam layer and its insulating properties. A refined dynamic temperature prediction model, taking into account the effect of foam, was set up. Simulation studies for a WWTP treating highly concentrated (manure) wastewater revealed that the foam layer had a significant effect on temperature prediction (3.8 ± 0.7 K over the year) and thus on the theoretical heat recovery potential (30% reduction when foam is not considered). Seasonal effects on the individual heat losses and heat gains were assessed. Additionally, the effects of the critical basin temperature above which heat is recovered, foam thickness, surface evaporation rate reduction and the non-absorbed solar radiation on the theoretical heat recovery potential were evaluated.

  11. Seasonality of the urban heat island effect: patterns and drivers

    NASA Astrophysics Data System (ADS)

    Schatz, J.; Kucharik, C. J.

    2014-12-01

    We conducted a rigorous analysis of the drivers of seasonality in the urban heat island (UHI) effect. Many studies report annual cycles in UHI intensity and have attributed those patterns to various hypotheses, including seasonal trends in wind and clouds, prevalence of anti-cyclonic conditions, soil moisture, and day length. But to our knowledge, those hypotheses have never been tested, leaving a substantial gap in our basic understanding of the urban climate. We tested these and other hypotheses using two years of continuous temperature measurements from an array of 150 sensors in and around Madison, Wisconsin USA, an urban area of 407,000 surrounded by lakes and a rural landscape of agriculture, forests, wetlands, and grasslands. This is one of the best replicated urban climate arrays ever deployed, which allowed us to characterize the UHI in rich spatial and temporal detail and rigorously assess the biophysical and synoptic drivers of its seasonal variation. UHI intensities were typically highest in summer and lowest in winter. Seasonal trends in wind speed and cloud cover generally tracked annual trends in UHI intensity, with the clearer, calmer conditions conducive to stronger UHIs more common in summer. This is consistent with the hypothesis that seasonal trends in wind, clouds, and anti-cyclonic conditions drive UHI seasonality. However, clear, calm summer nights still had higher UHI intensities than clear, calm winter nights, indicating that some background factor shifted baseline UHI intensities throughout the year. We found that regional vegetation and snow cover conditions set distinct seasonal baselines for UHI intensity, with nighttime intensities averaging 4°C in summer and 1°C in winter. Synoptic and biophysical factors that vary on shorter time scales (e.g. wind, clouds, soil moisture, relative humidity) modified daily UHI intensity around those baselines by 1-3°C but were not the primary drivers of UHI seasonality, contrary to the most common

  12. Modifying Effect of Heat Waves on the Relationship between Temperature and Mortality

    PubMed Central

    2016-01-01

    Studies conducted to evaluate temporal trends of heat-related mortality have not considered the effects of heat waves; although it is known they can affect mortality and act as a modifying factor. After adjusting for long-term trends and seasonality, the effects of temperature on non-accidental deaths in Seoul and Busan (inland and coastal cities, respectively) were analyzed using a generalized additive model of Poisson distribution. We evaluated temporal trends of heat-related mortalities in four periods (1991-1995, 1996-2000, 2001-2005, and 2006-2012). The effects of temperature on mortality were evaluated according to the occurrence of a heat wave and results were compared in the two cities. The effect of temperature on mortality was the greatest in 1991-1995 in Seoul; no significant change was observed in Busan. When we stratified the study period by heat wave status, the risk increase in mortality was 15.9% per 1℃ during years with a heat wave in Seoul, which was much higher than 0.31% increase observed during years without a heat wave. On the other hand, Busan showed a linear relationship between temperature and mortality and no significant difference between years with or without a heat wave. Variations in the relationship between temperature and mortality could be misunderstood if heat waves are not considered. Furthermore, heterogeneity was found in the modifying effect of heat waves on heat-related mortality in inland and coastal cities. The findings of this study help understand relations between temperature and mortality. PMID:27134490

  13. Modifying Effect of Heat Waves on the Relationship between Temperature and Mortality.

    PubMed

    Lee, Won Kyung; Lee, Hye Ah; Park, Hyesook

    2016-05-01

    Studies conducted to evaluate temporal trends of heat-related mortality have not considered the effects of heat waves; although it is known they can affect mortality and act as a modifying factor. After adjusting for long-term trends and seasonality, the effects of temperature on non-accidental deaths in Seoul and Busan (inland and coastal cities, respectively) were analyzed using a generalized additive model of Poisson distribution. We evaluated temporal trends of heat-related mortalities in four periods (1991-1995, 1996-2000, 2001-2005, and 2006-2012). The effects of temperature on mortality were evaluated according to the occurrence of a heat wave and results were compared in the two cities. The effect of temperature on mortality was the greatest in 1991-1995 in Seoul; no significant change was observed in Busan. When we stratified the study period by heat wave status, the risk increase in mortality was 15.9% per 1℃ during years with a heat wave in Seoul, which was much higher than 0.31% increase observed during years without a heat wave. On the other hand, Busan showed a linear relationship between temperature and mortality and no significant difference between years with or without a heat wave. Variations in the relationship between temperature and mortality could be misunderstood if heat waves are not considered. Furthermore, heterogeneity was found in the modifying effect of heat waves on heat-related mortality in inland and coastal cities. The findings of this study help understand relations between temperature and mortality. PMID:27134490

  14. Experimental and Numerical Studies of the Effects of Water Sprinkling on Urban Pavement on Heat Island Mitigation

    NASA Astrophysics Data System (ADS)

    Yoshioka, M.; Tosaka, H.; Nakagawa, K.

    2007-12-01

    One of the main causes of 'heat island phenomeno' is thought to be the artificial covers of the ground surface with asphalt or concrete which reduce greatly inherent cooling effect of water evaporation from soil surface. In this study, as a candidate method of mitigating the heat island the effects of the 'water sprinkling' on the pavements are discussed from field experiments and numerical studies. Three field experiments of water sprinkling on the asphalt/concrete pavements were performed in hot summer days in 2004-2006. For detecting the change in temperatures, the authors developed and used a 3-D measurements system which consists of two vertical planes with 6m high and 16m wide, and has network arrays of 102 thermistors distributed spatially in the planes. The temperatures measured in and around the water sprinkled area indicated that the ground surface temperature decreased 5 to 15 degrees uniformly in the water sprinkled area compared with those in the un-sprinkled area, while the relative decrease of atmospheric temperature was approximately up to 1 degree. The subsurface temperature at a depth of 14cm under the pavement decreased significantly and kept lower than that at the same depth in un-sprinkled area over the next morning. A numerical model was developed and applied to interpret the experimental results. It deals with the heat balance of radiation, sensible/latent heat transfer at the ground surface and heat conduction through the artificial and natural soil layer under ground. temperature and vapor conditions changes at and near ground surface were modeled by using the bulk formula.Good agreements between the calculated time-temperature profiles and the experimental ones were obtained by assuming adequate physical parameters and meteorological conditions. The model could be improved in order to evaluate the changes of temperature and vapor contents in atmosphere near the ground surface caused by aerodynamic turbulent diffusion.

  15. MHD Stagnation-Point Flow and Heat Transfer with Effects of Viscous Dissipation, Joule Heating and Partial Velocity Slip

    NASA Astrophysics Data System (ADS)

    Mat Yasin, Mohd Hafizi; Ishak, Anuar; Pop, Ioan

    2015-12-01

    The steady two-dimensional stagnation-point flow and heat transfer past a permeable stretching/shrinking sheet with effects of viscous dissipation, Joule heating and partial velocity slip in the presence of a magnetic field is investigated. The partial differential equations are reduced to nonlinear ordinary differential equations by using a similarity transformation, before being solved numerically by shooting technique. Results indicate that the skin friction coefficient and the local Nusselt number increase as magnetic parameter increases. It is found that for the stretching sheet the solution is unique while for the shrinking sheet there exist nonunique solutions (dual solutions) in certain range of parameters. The stability analysis shows that the upper branch solution is stable while the lower branch solution is unstable.

  16. MHD Stagnation-Point Flow and Heat Transfer with Effects of Viscous Dissipation, Joule Heating and Partial Velocity Slip

    PubMed Central

    Mat Yasin, Mohd Hafizi; Ishak, Anuar; Pop, Ioan

    2015-01-01

    The steady two-dimensional stagnation-point flow and heat transfer past a permeable stretching/shrinking sheet with effects of viscous dissipation, Joule heating and partial velocity slip in the presence of a magnetic field is investigated. The partial differential equations are reduced to nonlinear ordinary differential equations by using a similarity transformation, before being solved numerically by shooting technique. Results indicate that the skin friction coefficient and the local Nusselt number increase as magnetic parameter increases. It is found that for the stretching sheet the solution is unique while for the shrinking sheet there exist nonunique solutions (dual solutions) in certain range of parameters. The stability analysis shows that the upper branch solution is stable while the lower branch solution is unstable. PMID:26647651

  17. MHD Stagnation-Point Flow and Heat Transfer with Effects of Viscous Dissipation, Joule Heating and Partial Velocity Slip.

    PubMed

    Yasin, Mohd Hafizi Mat; Ishak, Anuar; Pop, Ioan

    2015-01-01

    The steady two-dimensional stagnation-point flow and heat transfer past a permeable stretching/shrinking sheet with effects of viscous dissipation, Joule heating and partial velocity slip in the presence of a magnetic field is investigated. The partial differential equations are reduced to nonlinear ordinary differential equations by using a similarity transformation, before being solved numerically by shooting technique. Results indicate that the skin friction coefficient and the local Nusselt number increase as magnetic parameter increases. It is found that for the stretching sheet the solution is unique while for the shrinking sheet there exist nonunique solutions (dual solutions) in certain range of parameters. The stability analysis shows that the upper branch solution is stable while the lower branch solution is unstable. PMID:26647651

  18. Towards understanding of heat effects in metallic glasses on the basis of macroscopic shear elasticity

    PubMed Central

    Mitrofanov, Y. P.; Wang, D. P.; Makarov, A. S.; Wang, W. H.; Khonik, V. A.

    2016-01-01

    It is shown that all heat effects taking place upon annealing of a metallic glass within the glassy and supercooled liquid states, i.e. heat release below the glass transition temperature and heat absorption above it, as well as crystallization-induced heat release, are related to the macroscopic shear elasticity. The underlying physical reason can be understood as relaxation in the system of interstitialcy-type ”defects” (elastic dipoles) frozen-in from the melt upon glass production. PMID:26975587

  19. The effect of free-stream turbulence on heat transfer from a flat plate

    NASA Technical Reports Server (NTRS)

    Sugawara, Sugao; Sato, Takashi; Komatsu, Hiroyasu; Osaka, Hiroichi

    1958-01-01

    Turbulence was generated by using screens, and the turbulence percentage was measured by a hot-wire anemometer both in the boundary layer and the free stream. The local heat-transfer coefficient was measured at 12 locations along the plate for the cases of various turbulence levels. The transition Reynolds number from laminar to turbulent flow decreases as the main-stream turbulence level increases. In the range of laminar heat transfer the effect of turbulence in the main flow was not great, but in the range of turbulent heat transfer the heat-transfer coefficient increases according to the increase of turbulence.

  20. Effects of forced wall vibration on the onset of flow instability and critical heat flux in uniformly-heated microchannels

    NASA Astrophysics Data System (ADS)

    Stromberger, Jorg Hermann

    Numerous experimental and theoretical investigations on two-phase flow instability and burnout in heated microchannels have been reported in the literature. However none of these investigations deals with the possible effects of wall vibrations on such flow boiling processes within microchannels. Fluid-structure interaction in ultra high power density systems cooled by high velocity single phase forced convection in microchannels may result in vibration amplitudes that are a significant fraction of the diameter of the channel. Such vibrations may significantly impact vapor bubble dynamics at the wall and, hence, the limiting heat fluxes corresponding to the onset of flow instability and/or burnout. The primary purpose of this research was to experimentally quantify the effect of forced wall vibration on the onset of flow instability (OFI) and the critical heat flux (CHF) in uniformly-heated annular microchannels. The secondary interest of this investigation was to compare the experimental data collected in the single-phase regime to commonly used single-phase forced convection correlations. Experimental data acquired in the flow boiling regime were to be utilized to confirm the validity of common flow boiling correlations for microchannel flow. The influence of forced wall vibration on subcooled single-phase forced convection and flow boiling was examined. The Georgia Tech Microchannel Test Facility (GTMTF) was modified to allow such experiments to be conducted at controlled values of transverse wall vibration amplitudes and accelerations for a range of frequencies. The channel demand curves were obtained for various inner and outer surface heat fluxes. Experiments were conducted for broad ranges of transverse wall vibration amplitudes over a range of frequencies. The experiments conducted in this investigation provide designers of high power density systems cooled by forced convection in microchannels with the appropriate data and correlations to confidently

  1. Effect of Conceptual Change Oriented Instruction on Students' Understanding of Heat and Temperature Concepts

    ERIC Educational Resources Information Center

    Baser, Mustafa

    2006-01-01

    This study explores the effectiveness of conceptual change oriented instruction and standard science instruction and contribution of logical thinking ability on seventh grade students' understanding of heat and temperature concepts. Misconceptions related to heat and temperature concepts were determined by related literature on this subject.…

  2. Seebeck effect influence on joule heat evolution in electrically conductive silicate materials

    NASA Astrophysics Data System (ADS)

    Fiala, Lukáš; Medved, Igor; Maděra, Jiří; Černý, Robert

    2016-07-01

    In general, silicate building materials are non-conductive matters that are not able to evolve heat when they are subjected to an external voltage. However, the electrical conductivity can be increased by addition of electrically conductive admixtures in appropriate amount which leads to generation of conductive paths in materials matrix. Such enhanced materials can evolve Joule heat and are utilizable as a core of self-heating or snow-melting systems. In this paper, Joule heat evolution together with Seebeck effect in electrically conductive silicate materials was taken into consideration and the model based on heat equation with included influence of DC electric field was proposed. Besides, a modeling example of heating element was carried out on FEM basis and time development of temperature in chosen surface points was expressed in order to declare ability of such system to be applicable.

  3. Effect of Heating Rate on Recrystallization of Twin Roll Cast Aluminum

    NASA Astrophysics Data System (ADS)

    Sun, Naiyu; Patterson, Burton R.; Suni, Jaakko P.; Doherty, Roger D.; Weiland, Hasso; Kadolkar, Puja; Blue, Craig A.; Thompson, Gregory B.

    2008-01-01

    The effect of heating rate on precipitation and recrystallization behavior in twin roll cast (TRC) AA3105 has been investigated by three different means: conventional air furnace, controlled infrared, and lead bath heating. Experimental results showed that as-recrystallized grain size decreased and became more equiaxed as the annealing heating rate increased. These results were explained via time-temperature-transformation (TTT) curves for both dispersoid precipitation and recrystallization. With the faster heating rate, recrystallization could occur before precipitation of Mn present in the unhomogenized TRC samples. At a heating rate of 50 °C/s, the material underwent grain growth after recrystallization at 500 °C. No sign of grain growth was observed in materials annealed with lower heating rates, 3 °C/s, 0.5 °C/s, and 0.01 °C/s, due to greater dispersoid precipitation.

  4. Effect of adiabatic square ribs on natural convection in an asymmetrically heated channel

    NASA Astrophysics Data System (ADS)

    Abidi-Saad, Aissa; Kadja, Mahfoud; Popa, Catalin; Polidori, Guillaume

    2016-06-01

    A 2-D numerical simulation is carried out to investigate the effect of two adiabatic square ribs on laminar flow and heat transfer in an asymmetrically heated channel. The two ribs are symmetrically located on each wall, exactly above the heating zone. The computational procedure is made by solving the unsteady bi-dimensional continuity, momentum and energy equations with the finite volume method. The investigations focused more specifically on the influence of ribs sizes on the flow structure and heat transfer enhancement. The results showed that the variation of ribs sizes significantly alters the heat transfer and fluid flow distribution along the channel, especially in the vicinity of protrusions. Also, the results show that streamlines, isotherms, and the number, sizes and formation of vortex structures inside the channel strongly depend on the size of protrusions. The changes in heat transfer parameters have also been presented.

  5. Heat stress management program improving worker health and operational effectiveness: a case study.

    PubMed

    Huss, Rosalyn G; Skelton, Scott B; Alvis, Kimberly L; Shane, Leigh A

    2013-03-01

    Heat stress monitoring is a vital component of an effective health and safety program when employees work in exceptionally warm environments. Workers at hazardous waste sites often wear personal protective equipment (PPE), which increases the body heat stress load. No specific Occupational Safety and Health Administration (OSHA) regulations address heat stress; however, OSHA does provide several guidance documents to assist employers in addressing this serious workplace health hazard. This article describes a heat stress and surveillance plan implemented at a hazardous waste site as part of the overall health and safety program. The PPE requirement for work at this site, coupled with extreme environmental temperatures, made heat stress a significant concern. Occupational health nurses and industrial hygienists developed a monitoring program for heat stress designed to prevent the occurrence of significant heat-related illness in site workers. The program included worker education on the signs of heat-related illness and continuous physiologic monitoring to detect early signs of heat-related health problems. Biological monitoring data were collected before workers entered the exclusion zone and on exiting the zone following decontamination. Sixty-six site workers were monitored throughout site remediation. More than 1,700 biological monitoring data points were recorded. Outcomes included improved worker health and safety, and increased operational effectiveness. PMID:23429639

  6. Interactive effect of aging and local muscle heating on renal vasoconstriction during isometric handgrip.

    PubMed

    Kuipers, Nathan T; Sauder, Charity L; Kearney, Matthew L; Ray, Chester A

    2009-08-01

    The purpose of the study was to determine the interactive effect of aging and forearm muscle heating on renal vascular conductance and muscle sympathetic nerve activity (MSNA) during ischemic isometric handgrip. A tube-lined, water-perfused sleeve was used to heat the forearm in 12 young (27 +/- 1 yr) and 9 older (63 +/- 1 yr) subjects. Ischemic isometric handgrip was performed before and after heating. Muscle temperature (intramuscular thermistor) was 34.3 +/- 0.2 and 38.7 +/- 0.1 degrees C during normothermia and heating, respectively. At rest, heating had no effect on renal blood velocity (Doppler ultrasound) or renal vascular conductance in either group (young, n = 12; older, n = 8). Heating compared with normothermia caused a significantly greater increase in renal vasoconstriction during exercise and postexercise muscle ischemia (PEMI) in both groups. However, the increase in renal vasoconstriction during heating was greater in the older compared with the young subjects (18 +/- 3 vs. 8 +/- 3%). During handgrip, heating elicited greater increases in MSNA responses in the older group (young, n = 12; older, n = 6), whereas no statistical difference was observed between groups during PEMI. In summary, aging augments renal vascular responses to ischemic isometric handgrip during heating of the exercising muscle. The greater renal vasoconstriction was associated with augmented MSNA in the older subjects.

  7. Effects of physical conditioning on heat tolerance in chemical-defense gear. Master's thesis

    SciTech Connect

    Nauss, M.M.

    1986-06-01

    Today the threat of chemical warfare is real. The only effective defense is the use of chemical defense gear and gas masks. Since they render chemical-warfare gases and liquids impermeable to penetration, they also prohibit sweat evaporation in conditions of thermal stress and thus, contribute to heat illness development. Historically, it has been the hot, humid tropics where United Nation's peacekeeping forces have been called, thus the use of chemical-defense gear in these regions is a realistic possibility and heat illness could affect the outcome of any mission carried out there. The human body only operates within a narrow range of core temparatures, and heat illness is the result of a breakdown in homeostasis. Many factors influence heat tolerance, thus maintaining core temperature within a safe range. Adequate hydration, acclimitization to heat, low body weight, young age, low alcohol intake, and physical fitness all contribute to heat tolerance. This proposal attempts to look specifically at the effect of physical conditioning on heat tolerance in chemical-defense gear as a possible solution to the heat-stress problem noted in this gear. Trainee graduates attending technical training schools at Lackland AFB, Texas, will be tested for maximum oxygen uptake (VO/2max) and heat tolerance time (HTT) in chemical defense gear on bicycle ergometers at Brooks AFB, Texas. Half of these subjects will be physically conditioned for 12 weeks.

  8. Heat stress management program improving worker health and operational effectiveness: a case study.

    PubMed

    Huss, Rosalyn G; Skelton, Scott B; Alvis, Kimberly L; Shane, Leigh A

    2013-03-01

    Heat stress monitoring is a vital component of an effective health and safety program when employees work in exceptionally warm environments. Workers at hazardous waste sites often wear personal protective equipment (PPE), which increases the body heat stress load. No specific Occupational Safety and Health Administration (OSHA) regulations address heat stress; however, OSHA does provide several guidance documents to assist employers in addressing this serious workplace health hazard. This article describes a heat stress and surveillance plan implemented at a hazardous waste site as part of the overall health and safety program. The PPE requirement for work at this site, coupled with extreme environmental temperatures, made heat stress a significant concern. Occupational health nurses and industrial hygienists developed a monitoring program for heat stress designed to prevent the occurrence of significant heat-related illness in site workers. The program included worker education on the signs of heat-related illness and continuous physiologic monitoring to detect early signs of heat-related health problems. Biological monitoring data were collected before workers entered the exclusion zone and on exiting the zone following decontamination. Sixty-six site workers were monitored throughout site remediation. More than 1,700 biological monitoring data points were recorded. Outcomes included improved worker health and safety, and increased operational effectiveness.

  9. Effects of heat treatment on the mechanical properties of kenaf fiber

    NASA Astrophysics Data System (ADS)

    Carada, Paulo Teodoro D. L.; Fujii, Toru; Okubo, Kazuya

    2016-05-01

    Natural fibers are utilized in various ways. One specific application of it, is in the field natural fiber composite (NFC). Considerable amount of researches are conducted in this field due to rising concerns in the harmful effects of synthetic materials to the environment. Additionally, these researches are done in order to overcome the drawbacks which limit the wide use of natural fiber. A way to improve NFC is to look into the reinforcing component (natural fiber). Treatments, which are classified as mechanical or chemical in nature, can be done in order to improve the performance of the natural fiber. The aim of this study is to assess the effects of heat treatment in the mechanical properties of kenaf fiber. In addition, the response of mechanical properties after exposure to high moisture environment of heat-treated kenaf fibers was observed. Heat treatment was done for one hour with the following heating temperatures: 140, 160, 180, and 200 °C. X-ray diffraction analysis was done to calculate the crystallinity index of kenaf fibers after heat treatment. The results showed that increase in tensile strength can be attained when kenaf fibers are heat treated at 140 °C. However, the tensile modulus showed inconsistency with respect to heat treatment temperature. The computed crystallinity index of the fiber matched the tensile strength observed in non-treated and heat-treated kenaf fibers. The results obtained in this study can be used for applications where heat treatment on kenaf fibers is needed.

  10. The impact of temperature on mortality in a subtropical city: effects of cold, heat, and heat waves in São Paulo, Brazil.

    PubMed

    Son, Ji-Young; Gouveia, Nelson; Bravo, Mercedes A; de Freitas, Clarice Umbelino; Bell, Michelle L

    2016-01-01

    Understanding how weather impacts health is critical, especially under a changing climate; however, relatively few studies have investigated subtropical regions. We examined how mortality in São Paulo, Brazil, is affected by cold, heat, and heat waves over 14.5 years (1996-2010). We used over-dispersed generalized linear modeling to estimate heat- and cold-related mortality, and Bayesian hierarchical modeling to estimate overall effects and modification by heat wave characteristics (intensity, duration, and timing in season). Stratified analyses were performed by cause of death and individual characteristics (sex, age, education, marital status, and place of death). Cold effects on mortality appeared higher than heat effects in this subtropical city with moderate climatic conditions. Heat was associated with respiratory mortality and cold with cardiovascular mortality. Risk of total mortality was 6.1% (95% confidence interval 4.7, 7.6%) higher at the 99th percentile of temperature than the 90th percentile (heat effect) and 8.6% (6.2, 11.1%) higher at the 1st compared to the 10th percentile (cold effect). Risks were higher for females and those with no education for heat effect, and males for cold effect. Older persons, widows, and non-hospital deaths had higher mortality risks for heat and cold. Mortality during heat waves was higher than on non-heat wave days for total, cardiovascular, and respiratory mortality. Our findings indicate that mortality in São Paulo is associated with both cold and heat and that some subpopulations are more vulnerable. PMID:25972308

  11. The impact of temperature on mortality in a subtropical city: effects of cold, heat, and heat waves in São Paulo, Brazil

    NASA Astrophysics Data System (ADS)

    Son, Ji-Young; Gouveia, Nelson; Bravo, Mercedes A.; de Freitas, Clarice Umbelino; Bell, Michelle L.

    2016-01-01

    Understanding how weather impacts health is critical, especially under a changing climate; however, relatively few studies have investigated subtropical regions. We examined how mortality in São Paulo, Brazil, is affected by cold, heat, and heat waves over 14.5 years (1996-2010). We used over-dispersed generalized linear modeling to estimate heat- and cold-related mortality, and Bayesian hierarchical modeling to estimate overall effects and modification by heat wave characteristics (intensity, duration, and timing in season). Stratified analyses were performed by cause of death and individual characteristics (sex, age, education, marital status, and place of death). Cold effects on mortality appeared higher than heat effects in this subtropical city with moderate climatic conditions. Heat was associated with respiratory mortality and cold with cardiovascular mortality. Risk of total mortality was 6.1 % (95 % confidence interval 4.7, 7.6 %) higher at the 99th percentile of temperature than the 90th percentile (heat effect) and 8.6 % (6.2, 11.1 %) higher at the 1st compared to the 10th percentile (cold effect). Risks were higher for females and those with no education for heat effect, and males for cold effect. Older persons, widows, and non-hospital deaths had higher mortality risks for heat and cold. Mortality during heat waves was higher than on non-heat wave days for total, cardiovascular, and respiratory mortality. Our findings indicate that mortality in São Paulo is associated with both cold and heat and that some subpopulations are more vulnerable.

  12. Raman probing of competitive laser heating and local recrystallization effect in ZnO nanocrystals.

    PubMed

    Ye, J D; Parkinson, P; Ren, F F; Gu, S L; Tan, H H; Jagadish, C

    2012-10-01

    The competitive laser-induced local heating and recrystallization effects in ZnO nanocrystals embedded in a MgO/ZnO stack are reported via resonance Raman spectra. The dependence of the intensity, energy, and resonance effects of the longitudinal optical (LO) phonon on laser excitation condition are discussed in the context of Fröhlich interaction. Redistribution of defects, impurity-diffusion, and grain regrowth caused by thermal and photochemical effects lead to significant changes in coupling strength of electron-phonon interaction, and the resonance behaviors are strongly affected by the interplay of local heating, heat trapping, and local structural modification in such nanostructures.

  13. Effects of secondary flow on heat transfer in rotating passages

    NASA Astrophysics Data System (ADS)

    Moore, Joan G.; Moore, John

    1990-02-01

    Secondary flow in rotating cooling passages of jet engine turbine rotors is considered. A Navier-Stokes calculation procedure for turbulent flow is used to compute flow development in a radially outward flow channel, round a sharp 180 degree bend, and in the radially inward flow channel downstream. Areas of high and low heat transfer are explained by secondary flow development and quantitative results show regions of design interest.

  14. Heat release effects on the instability of parallel shear layers

    NASA Technical Reports Server (NTRS)

    Hegde, U.

    1994-01-01

    The influence of time-dependent heat addition on the linear instablity of shear layers is of considerable interest in understanding the dynamic behavior of reacting flows and combustion-turbulence interactions. The approach is based upon the Bernoulli enthalpy aeroacoustics theory, which utilizes the specific enthalpy and specific entropy as the primary thermodynamic variables. In addition, velocity oscillations are split into Helmoholtz decomposition theorem.

  15. Effect of heat moisture treatment on physicochemical and morphological properties of wheat starch and xylitol mixture.

    PubMed

    Sun, Qingjie; Dai, Lei; Nan, Chong; Xiong, Liu

    2014-01-15

    The effect of heat moisture treatment (HMT, 100°C, 10h) on the physicochemical and morphological properties of wheat starch and xylitol mixture (SX) were studied by using Rapid Visco-Analyser (RVA), differential scanning calorimetry (DSC), scanning electron microscope (SEM) and X-ray diffraction pattern (X-ray). The research found that the peak viscosity (PV), trough viscosity (TV), final viscosity (FV) and breakdown (BD) of SX decreased markedly after HMT, whereas pasting temperature increased. Compared with SX, To, Tp and Tc of SX treated with HMT (H-SX) increased and ΔH decreased. The results of SEM showed that numerous xylitol granules appeared on the surface of starch granule in SX, and a layer of similar membrane adhered on the surface of starch granules in H-SX. After gelatinization and freeze-dried, the gel network structure of H-SX was tighter than that of SX. The amorphous region of H-SX was higher than that of SX.

  16. The effect of nanoparticles added to heated micropolar fluid

    NASA Astrophysics Data System (ADS)

    Nering, Konrad; Rup, Kazimierz

    2016-10-01

    This paper presents an analysis of momentum, angular momentum and heat transfer during the unsteady natural convection in micropolar nanofluids. Presented phenomena are modelled in the vicinity of a vertical plate and heat flux which rises suddenly at a given moment, using the boundary layer concept. Differential equations of angular momentum conservation are used according to the theory of micropolar fluids developed by Eringen. Finite difference method is used to solve the equations for conservation of mass, energy, momentum and angular momentum. Selected nanofluids treated as single phase fluids contain small particles with diameter size d = 10 nm and d = 38.4 nm. In particular, two ethylene glycol based nanofluids and one water-based nanofluid are analysed. Volume fraction of these solutions is 6%. First ethylene glycol solution contain Al2 O3 nanoparticles (d = 38.4 nm), and the second ethylene glycol solution contained Cu nanoparticles (d = 10 nm). Water based nanofluid contain Al2 O3 nanoparticles (d = 38.4 nm). As a result of solving conservation equations, unsteady velocity field (U, V), temperature (T), microrotation component normal to (x, y) plane (N), velocity gradient ∂U/∂Y and temperature gradient ∂T/∂Y are obtained. These results are compared to theoretical and experimental results presented in literature. At the end of this paper, heat transfer enhancement for analysed nanofluids is estimated.

  17. Effect of microfouling on heat-transfer efficiency

    SciTech Connect

    Little, B.; Berger, L.R.

    1980-01-01

    Field experiments, performed at Keahole Point, Hawaii and in the Gulf of Mexico, were designed to determine the relationship between decreased heat transfer efficiency and the accumulation of corrosion and/or biofouling films on heat exchanger surfaces. The sample tubes were maintained under conditions simulating those of an Ocean Thermal Energy Conversion (OTEC) system and data from the two sites have been compared. Seawater flowed through 2.54 (internal diameter) metal tubes at approximately 1.8m sec/sup -1/. Four types of tubes were used: 5052 Aluminum (A1), Grade 2 titanium (Ti), 90-10 copper-nickel (Cu-Ni) and Allegheny-Ludlum 6X stainless ssteel (SS). All surfaces were colonized by microorganisms, though colonization of the Cu-Ni surface was initially retarded. Total film weight was greatest for the Al and Cu-Ni surfaces which were characterized by corrosion as well as microbial fouling. The total organic carbon: total nitrogen ratios of the fouling films from Ti, Al, SS and Cu-Ni, 4.2, 4.0, 4.8 and 7.9 respectively, remained constant throughout the experiment. The degradation of heat transfer efficiency due to the formation of fouling layers on Ti and SS is neither linear nor a simple exponential function. A microfouling model is proposed for corrosion-resistant surfaces that is consistent with field observations.

  18. Multiplex networks in metropolitan areas: generic features and local effects.

    PubMed

    Strano, Emanuele; Shai, Saray; Dobson, Simon; Barthelemy, Marc

    2015-10-01

    Most large cities are spanned by more than one transportation system. These different modes of transport have usually been studied separately: it is however important to understand the impact on urban systems of coupling different modes and we report in this paper an empirical analysis of the coupling between the street network and the subway for the two large metropolitan areas of London and New York. We observe a similar behaviour for network quantities related to quickest paths suggesting the existence of generic mechanisms operating beyond the local peculiarities of the specific cities studied. An analysis of the betweenness centrality distribution shows that the introduction of underground networks operate as a decentralizing force creating congestion in places located at the end of underground lines. Also, we find that increasing the speed of subways is not always beneficial and may lead to unwanted uneven spatial distributions of accessibility. In fact, for London—but not for New York—there is an optimal subway speed in terms of global congestion. These results show that it is crucial to consider the full, multimodal, multilayer network aspects of transportation systems in order to understand the behaviour of cities and to avoid possible negative side-effects of urban planning decisions. PMID:26400198

  19. Multiplex networks in metropolitan areas: generic features and local effects.

    PubMed

    Strano, Emanuele; Shai, Saray; Dobson, Simon; Barthelemy, Marc

    2015-10-01

    Most large cities are spanned by more than one transportation system. These different modes of transport have usually been studied separately: it is however important to understand the impact on urban systems of coupling different modes and we report in this paper an empirical analysis of the coupling between the street network and the subway for the two large metropolitan areas of London and New York. We observe a similar behaviour for network quantities related to quickest paths suggesting the existence of generic mechanisms operating beyond the local peculiarities of the specific cities studied. An analysis of the betweenness centrality distribution shows that the introduction of underground networks operate as a decentralizing force creating congestion in places located at the end of underground lines. Also, we find that increasing the speed of subways is not always beneficial and may lead to unwanted uneven spatial distributions of accessibility. In fact, for London—but not for New York—there is an optimal subway speed in terms of global congestion. These results show that it is crucial to consider the full, multimodal, multilayer network aspects of transportation systems in order to understand the behaviour of cities and to avoid possible negative side-effects of urban planning decisions.

  20. Multiplex networks in metropolitan areas: generic features and local effects

    PubMed Central

    Strano, Emanuele; Shai, Saray; Dobson, Simon; Barthelemy, Marc

    2015-01-01

    Most large cities are spanned by more than one transportation system. These different modes of transport have usually been studied separately: it is however important to understand the impact on urban systems of coupling different modes and we report in this paper an empirical analysis of the coupling between the street network and the subway for the two large metropolitan areas of London and New York. We observe a similar behaviour for network quantities related to quickest paths suggesting the existence of generic mechanisms operating beyond the local peculiarities of the specific cities studied. An analysis of the betweenness centrality distribution shows that the introduction of underground networks operate as a decentralizing force creating congestion in places located at the end of underground lines. Also, we find that increasing the speed of subways is not always beneficial and may lead to unwanted uneven spatial distributions of accessibility. In fact, for London—but not for New York—there is an optimal subway speed in terms of global congestion. These results show that it is crucial to consider the full, multimodal, multilayer network aspects of transportation systems in order to understand the behaviour of cities and to avoid possible negative side-effects of urban planning decisions. PMID:26400198

  1. Specially tailored transfinite-element formulations for hyperbolic heat conduction involving non-Fourier effects

    NASA Technical Reports Server (NTRS)

    Tamma, Kumar K.; Railkar, Sudhir B.

    1989-01-01

    The phenomenon of hyperbolic heat conduction in contrast to the classical (parabolic) form of Fourier heat conduction involves thermal energy transport that propagates only at finite speeds, as opposed to an infinite speed of thermal energy transport. To accommodate the finite speed of thermal wave propagation, a more precise form of heat flux law is involved, thereby modifying the heat flux originally postulated in the classical theory of heat conduction. As a consequence, for hyperbolic heat conduction problems, the thermal energy propagates with very sharp discontinuities at the wave front. Accurate solutions are found for a class of one-dimensional hyperbolic heat conduction problems involving non-Fourier effects that can be used effectively for representative benchmark tests and for validating alternate schemes. Modeling/analysis formulations via specially tailored hybrid computations are provided for accurately modeling the sharp discontinuities of the propagating thermal wave front. Comparative numerical test models are presented for various hyperbolic heat conduction models involving non-Fourier effects to demonstrate the present formulations.

  2. The effects of drying following heat shock exposure of the desert moss Syntrichia caninervis.

    PubMed

    Xu, Shu-Jun; Liu, Chun-Jiang; Jiang, Ping-An; Cai, Wei-Min; Wang, Yan

    2009-03-15

    Desert mosses are components of biological soil crusts (BSCs) and their ecological functions make assessment and protection of these mosses a high-ranking management priority in desert regions. Drying is thought to be useful for desert mosses surviving heat shock. In this study, we investigated the role of drying by monitoring the responses of physiological characters and asexual reproduction in the typical desert moss Syntrichia caninervis. Heat significantly decreased chlorophyll content and weakened rapid recovery of photochemical activity, and increased carotenoid content and membrane permeability. Lethal temperatures significantly destroyed shoot regeneration potential. In comparison with heat alone, drying significantly increased protonema emergence time and depressed protonema emergence area. Drying combined with heat accelerated water loss, followed by a decrease of photosynthetic activity. Drying had different influences on membrane permeability at different temperatures. When moss leaves were subjected to a combined stress of drying and heat shock, photosynthesis was maintained mainly due to the effects of drying on physiological activity although the cellular morphological integrity was affected. Drying caused opposing effects on moss physiological and reproductive characteristics. On the one hand, drying caused a positive synergistic effect with heat shock when the temperature was below 40 degrees C. On the other hand, drying showed antagonism with heat shock when the moss was subjected to temperatures higher than 40 degrees C. These findings may help in understanding the survival mechanism of dessert mosses under heat shock stress which will be helpful for the artificial reconstruction of BSCs.

  3. Effects of exposure to short-term heat stress on male reproductive fitness in a soil arthropod.

    PubMed

    Zizzari, Z Valentina; Ellers, Jacintha

    2011-03-01

    Ambient temperature is a key environmental factor influencing a variety of aspects of the ecology and evolution of ectotherms. Reproductive traits have been suggested to be more sensitive to thermal stress than other life history traits. This study investigated the direct and indirect effects of heat shock on male reproductive success in the widespread springtail Orchesella cincta. Male springtails were exposed to four temperature treatments: heat hardening (35.2°C for 1h), heat shock (37.2°C for 1h), heat hardening+heat shock (35.2°C for 1h, followed 15h later by 37.2°C for 1h), and control (20°C). The heat shock gene Hsp70 showed high expression in all the heat treatments, indicating that the treatments indeed induced thermal stress. Significant mortality was only found in the treatment with heat shock, both with and without heat hardening. A direct effect of heat treatment was found on time to first reproduction, which was significantly longer after heat shock (with or without heat hardening) than in the control treatment. There was no difference among treatments in the number of spermatophores produced in the first reproductive instar. Heat treatment also had indirect effects on male reproductive success. Females chose significantly more spermatophores from control males than from males that received heat shock, heat hardening or both. A high percentage of spermatophores produced by heat shocked males caused reproductive failure in females, but no significant differences among treatments were found. Our results suggest that not all traits were equally affected by the heat stress. Heat hardening did not protect reproductive traits against the negative effects of heat shock. The indirect effects of heat shock on reproduction may be equally important as the direct effects. PMID:21215753

  4. Effect of thermal interface on heat flow in carbon nanofiber composites.

    PubMed

    Gardea, F; Naraghi, M; Lagoudas, D

    2014-01-22

    The thermal transport process in carbon nanofiber (CNF)/epoxy composites is addressed through combined micromechanics and finite element modeling, guided by experiments. The heat exchange between CNF constituents and matrix is studied by explicitly accounting for interface thermal resistance between the CNFs and the epoxy matrix. The effects of nanofiber orientation and discontinuity on heat flow and thermal conductivity of nanocomposites are investigated through simulation of the laser flash experiment technique and Fourier's model of heat conduction. Our results indicate that when continuous CNFs are misoriented with respect to the average temperature gradient, the presence of interfacial resistance does not affect the thermal conductivity of the nanocomposites, as most of the heat flow will be through CNFs; however, interface thermal resistance can significantly alter the patterns of heat flow within the nanocomposite. It was found that very high interface resistance leads to heat entrapment at the interface near to the heat source, which can promote interface thermal degradation. The magnitude of heat entrapment, quantified via the peak transient temperature rise at the interface, in the case of high thermal resistance interfaces becomes an order of magnitude more intense as compared to the case of low thermal resistance interfaces. Moreover, high interface thermal resistance in the case of discontinuous fibers leads to a nearly complete thermal isolation of the fibers from the matrix, which will marginalize the contribution of the CNF thermal conductivity to the heat transfer in the composite.

  5. Effects of Hospital Workers’ Friendship Networks on Job Stress

    PubMed Central

    Shin, Sung Yae; Lee, Sang Gyu

    2016-01-01

    Background This study attempted to identify the sources of job stress according to job position and investigate how friendship networks affect job stress. Methods Questionnaires based on The Health Professions Stress Inventory (HPSI) developed by Wolfgang experienced by healthcare providers were collected from 420 nurses, doctors and radiological technologists in two general hospitals in Korea by a multistage cluster sampling method. Multiple regression analysis was used to examine the effects of friendship networks on job stress after controlling for other factors. Results The severity of job stress differed according to level of job demands (p = .006); radiologic technologists experienced the least stress (45.4), nurses experienced moderate stress (52.4), and doctors experienced the most stress (53.6). Those with long-term friendships characterized by strong connections reported lower levels of stress than did those with weak ties to friends among nurses (1.3, p < .05) and radiological technologists (11.4, p < .01). The degree of cohesion among friends had a positive impact on the level of job stress experienced by nurses (8.2, p < .001) and radiological technologists (14.6, p < .1). Doctors who participated in workplace alumni meetings scored higher than those who did not. However, those who participated in alumni meetings outside the workplace showed the opposite tendency, scoring 9.4 (p < .05) lower than those who did not. The resources from their friendship network include both information and instrumental support. As most radiological technologists were male, their instrumental support positively affected their job stress (9.2, p < .05). Life information support was the primary positive contributor to control of nurses’ (4.1, p < .05), radiological technologists’ (8.0, p < .05) job stress. Conclusion The strength and density of such friendship networks were related to job stress. Life information support from their friendship network was the primary

  6. Assessment of Self-Heating Susceptibility of Indian Coal Seams - A Neural Network Approach

    NASA Astrophysics Data System (ADS)

    Panigrahi, D. C.; Ray, S. K.

    2014-12-01

    The paper addresses an electro-chemical method called wet oxidation potential technique for determining the susceptibility of coal to spontaneous combustion. Altogether 78 coal samples collected from thirteen different mining companies spreading over most of the Indian Coalfields have been used for this experimental investigation and 936 experiments have been carried out by varying different experimental conditions to standardize this method for wider application. Thus for a particular sample 12 experiments of wet oxidation potential method were carried out. The results of wet oxidation potential (WOP) method have been correlated with the intrinsic properties of coal by carrying out proximate, ultimate and petrographic analyses of the coal samples. Correlation studies have been carried out with Design Expert 7.0.0 software. Further, artificial neural network (ANN) analysis was performed to ensure best combination of experimental conditions to be used for obtaining optimum results in this method. All the above mentioned analysis clearly spelt out that the experimental conditions should be 0.2 N KMnO4 solution with 1 N KOH at 45°C to achieve optimum results for finding out the susceptibility of coal to spontaneous combustion. The results have been validated with Crossing Point Temperature (CPT) data which is widely used in Indian mining scenario. W pracy omówiono możliwości wykorzystania metody elektro-chemicznej zwanej metodą określania potencjału utleniającego w procesie mokrym do określania skłonności węgla do samozapłonu. Dla potrzeb eksperymentu zebrano 78 próbek węgla z trzynastu kopalni w obrębie Indyjskiego Zagłębia Węglowego. Przeprowadzono 936 eksperymentów, w różnych warunkach prowadzenia procesu aby zapewnić standaryzację metody w celu jej szerszego zastosowania. Dla każdej próbki przeprowadzono 12 eksperymentów metodą badania potencjału utleniającego w procesie mokrym. Wyniki skorelowano z własnościami danego węgla przez

  7. Prediction of heat release effects on a mixing layer

    NASA Technical Reports Server (NTRS)

    Farshchi, M.

    1986-01-01

    A fully second-order closure model for turbulent reacting flows is suggested based on Favre statistics. For diffusion flames the local thermodynamic state is related to single conserved scalar. The properties of pressure fluctuations are analyzed for turbulent flows with fluctuating density. Closure models for pressure correlations are discussed and modeled transport equations for Reynolds stresses, turbulent kinetic energy dissipation, density-velocity correlations, scalar moments and dissipation are presented and solved, together with the mean equations for momentum and mixture fraction. Solutions of these equations are compared with the experimental data for high heat release free mixing layers of fluorine and hydrogen in a nitrogen diluent.

  8. Electron beam heating effects during environmental scanning electron microscopy imaging of water condensation on superhydrophobic surfaces

    NASA Astrophysics Data System (ADS)

    Rykaczewski, K.; Scott, J. H. J.; Fedorov, A. G.

    2011-02-01

    Superhydrophobic surfaces (SHSs) show promise as promoters of dropwise condensation. Droplets with diameters below ˜10 μm account for the majority of the heat transferred during dropwise condensation but their growth dynamics on SHS have not been systematically studied. Due to the complex topography of the surface environmental scanning electron microscopy is the preferred method for observing the growth dynamics of droplets in this size regime. By studying electron beam heating effects on condensed water droplets we establish a magnification limit below which the heating effects are negligible and use this insight to study the mechanism of individual drop growth.

  9. The effect of channel convergence on heat transfer in a passage with short pin fins

    NASA Technical Reports Server (NTRS)

    Brigham, B. A.

    1984-01-01

    Array averaged heat transfer coefficients were obtained for two configurations of short pin fins in a converging channel and for two flat plate configurations in a converging channel. The effect of flow acceleration due to channel convergence and the effect of varying pin length on the heat transfer was determined. Results are presented in the form of Nusselt number versus Reynolds number for the four geometries tested.

  10. Effect of heat treatment on strength of clays

    SciTech Connect

    Joshi, R.C.; Achari, G. . Dept. of Civil Engineering); Horsfield, D. ); Nagaraj, T.S. . Dept. of Civil Engineering)

    1994-06-01

    Thermal treatment alters the physical and mechanical properties of clayey soils. Thermally treated soils have been used since primitive times for making trails for access and bricks for dwellings. In comparison with other soil-improvement methods, thermal stabilization produces immediate results. Thermal treatment of clays alters several material characteristics, such as strength, cohesion, internal friction angle, and resistance to abrasion. Furthermore, thermal treatment causes decrease in cation exchange and compressibility and increase in particle size. Aggregates produced by thermal treatment provide durable and economic substitutes for gravel and crushed rock. These are then used for pavement construction particularly in areas where construction materials have to be imported at excessive costs. Thus, in the Western Beaufort Sea area where large quantities of granular fill for artificial island and undersea-berm construction are required, but not readily available, thermally treated clays may be a solution. Granular material produced from a clayey soil must retain strength when wetted and be durable under wetting and drying conditions. Beyond fusion temperatures of clays, i.e. above 900 C, these conditions are known to be met. However, it is not clear from existing information, if heating below fusion temperatures may also satisfy these requirements. This study examines the relationship between the strength of selected clays and clay mixtures heated from 300 C to 700 C and the factors that influence such a relationship.

  11. Effects of Autumn and Spring Heat Waves on Seed Germination of High Mountain Plants.

    PubMed

    Orsenigo, Simone; Abeli, Thomas; Rossi, Graziano; Bonasoni, Paolo; Pasquaretta, Cristian; Gandini, Maurizia; Mondoni, Andrea

    2015-01-01

    Alpine plants are considered to be particularly vulnerable to climate change and related extreme episodes, such as heat waves. Despite growing interest in the impact of heat waves on alpine plants, knowledge about their effects on regeneration is still fragmentary. Recruitment from seeds will be crucial for the successful migration and survival of these species and will play a key role in their future adaptation to climate change. In this study, we assessed the impacts of heat waves on the seed germination of 53 high mountain plants from the Northern Apennines (Italy). The seeds were exposed to laboratory simulations of three seasonal temperature treatments, derived from real data recorded at a meteorological station near the species growing site, which included two heat wave episodes that occurred both in spring 2003 and in autumn 2011. Moreover, to consider the effect of increasing drought conditions related to heat waves, seed germination was also investigated under four different water potentials. In the absence of heat waves, seed germination mainly occurred in spring, after seeds had experienced autumn and winter seasons. However, heat waves resulted in a significant increase of spring germination in c. 30% of the species and elicited autumn germination in 50%. When heat waves were coupled with drought, seed germination decreased in all species, but did not stop completely. Our results suggest that in the future, heat waves will affect the germination phenology of alpine plants, especially conditionally dormant and strictly cold-adapted chorotypes, by shifting the emergence time from spring to autumn and by increasing the proportion of emerged seedlings. The detrimental effects of heat waves on recruitment success is less likely to be due to the inhibition of seed germination per se, but rather due to seedling survival in seasons, and temperature and water conditions that they are not used to experiencing. Changes in the proportion and timing of emergence

  12. Effects of Autumn and Spring Heat Waves on Seed Germination of High Mountain Plants.

    PubMed

    Orsenigo, Simone; Abeli, Thomas; Rossi, Graziano; Bonasoni, Paolo; Pasquaretta, Cristian; Gandini, Maurizia; Mondoni, Andrea

    2015-01-01

    Alpine plants are considered to be particularly vulnerable to climate change and related extreme episodes, such as heat waves. Despite growing interest in the impact of heat waves on alpine plants, knowledge about their effects on regeneration is still fragmentary. Recruitment from seeds will be crucial for the successful migration and survival of these species and will play a key role in their future adaptation to climate change. In this study, we assessed the impacts of heat waves on the seed germination of 53 high mountain plants from the Northern Apennines (Italy). The seeds were exposed to laboratory simulations of three seasonal temperature treatments, derived from real data recorded at a meteorological station near the species growing site, which included two heat wave episodes that occurred both in spring 2003 and in autumn 2011. Moreover, to consider the effect of increasing drought conditions related to heat waves, seed germination was also investigated under four different water potentials. In the absence of heat waves, seed germination mainly occurred in spring, after seeds had experienced autumn and winter seasons. However, heat waves resulted in a significant increase of spring germination in c. 30% of the species and elicited autumn germination in 50%. When heat waves were coupled with drought, seed germination decreased in all species, but did not stop completely. Our results suggest that in the future, heat waves will affect the germination phenology of alpine plants, especially conditionally dormant and strictly cold-adapted chorotypes, by shifting the emergence time from spring to autumn and by increasing the proportion of emerged seedlings. The detrimental effects of heat waves on recruitment success is less likely to be due to the inhibition of seed germination per se, but rather due to seedling survival in seasons, and temperature and water conditions that they are not used to experiencing. Changes in the proportion and timing of emergence

  13. Effect of body mass and melanism on heat balance in Liolaemus lizards of the goetschi clade.

    PubMed

    Moreno Azócar, Débora Lina; Bonino, Marcelo Fabián; Perotti, María Gabriela; Schulte, James A; Abdala, Cristian Simón; Cruz, Félix Benjamín

    2016-04-15

    The body temperature of ectotherms depends on the environmental temperatures and behavioral adjustments, but morphology may also have an effect. For example, in colder environments, animals tend to be larger and to show higher thermal inertia, as proposed by Bergmann's rule and the heat balance hypothesis (HBH). Additionally, dark coloration increases solar radiation absorption and should accelerate heat gain (thermal melanism hypothesis, TMH). We tested Bergmann's rule, the HBH and the TMH within the ITALIC! Liolaemus goetschilizard clade, which shows variability in body size and melanic coloration. We measured heating and cooling rates of live and euthanized animals, and tested how morphology and color affect these rates. Live organisms show less variable and faster heating rates compared with cooling rates, suggesting behavioral and/or physiological adjustments. Our results support Bergmann's rule and the HBH, as larger species show slower heating and cooling rates. However, we did not find a clear pattern to support the TMH. The influence of dorsal melanism on heating by radiation was masked by the body size effect in live animals, and results from euthanized individuals also showed no clear effects of melanism on heating rates. Comparison among three groups of live individuals with different degrees of melanism did not clarify the influence of melanism on heating rates. However, when euthanized animals from the same three groups were compared, we observed that darker euthanized animals actually heat faster than lighter ones, favoring the TMH. Although unresolved aspects remain, body size and coloration influenced heat exchange, suggesting complex thermoregulatory strategies in these lizards, probably regulated through physiology and behavior, which may allow these small lizards to inhabit harsh weather environments.

  14. Effect of body mass and melanism on heat balance in Liolaemus lizards of the goetschi clade.

    PubMed

    Moreno Azócar, Débora Lina; Bonino, Marcelo Fabián; Perotti, María Gabriela; Schulte, James A; Abdala, Cristian Simón; Cruz, Félix Benjamín

    2016-04-15

    The body temperature of ectotherms depends on the environmental temperatures and behavioral adjustments, but morphology may also have an effect. For example, in colder environments, animals tend to be larger and to show higher thermal inertia, as proposed by Bergmann's rule and the heat balance hypothesis (HBH). Additionally, dark coloration increases solar radiation absorption and should accelerate heat gain (thermal melanism hypothesis, TMH). We tested Bergmann's rule, the HBH and the TMH within the ITALIC! Liolaemus goetschilizard clade, which shows variability in body size and melanic coloration. We measured heating and cooling rates of live and euthanized animals, and tested how morphology and color affect these rates. Live organisms show less variable and faster heating rates compared with cooling rates, suggesting behavioral and/or physiological adjustments. Our results support Bergmann's rule and the HBH, as larger species show slower heating and cooling rates. However, we did not find a clear pattern to support the TMH. The influence of dorsal melanism on heating by radiation was masked by the body size effect in live animals, and results from euthanized individuals also showed no clear effects of melanism on heating rates. Comparison among three groups of live individuals with different degrees of melanism did not clarify the influence of melanism on heating rates. However, when euthanized animals from the same three groups were compared, we observed that darker euthanized animals actually heat faster than lighter ones, favoring the TMH. Although unresolved aspects remain, body size and coloration influenced heat exchange, suggesting complex thermoregulatory strategies in these lizards, probably regulated through physiology and behavior, which may allow these small lizards to inhabit harsh weather environments. PMID:26896550

  15. Effects of Autumn and Spring Heat Waves on Seed Germination of High Mountain Plants

    PubMed Central

    Orsenigo, Simone; Abeli, Thomas; Rossi, Graziano; Bonasoni, Paolo; Pasquaretta, Cristian; Gandini, Maurizia; Mondoni, Andrea

    2015-01-01

    Alpine plants are considered to be particularly vulnerable to climate change and related extreme episodes, such as heat waves. Despite growing interest in the impact of heat waves on alpine plants, knowledge about their effects on regeneration is still fragmentary. Recruitment from seeds will be crucial for the successful migration and survival of these species and will play a key role in their future adaptation to climate change. In this study, we assessed the impacts of heat waves on the seed germination of 53 high mountain plants from the Northern Apennines (Italy). The seeds were exposed to laboratory simulations of three seasonal temperature treatments, derived from real data recorded at a meteorological station near the species growing site, which included two heat wave episodes that occurred both in spring 2003 and in autumn 2011. Moreover, to consider the effect of increasing drought conditions related to heat waves, seed germination was also investigated under four different water potentials. In the absence of heat waves, seed germination mainly occurred in spring, after seeds had experienced autumn and winter seasons. However, heat waves resulted in a significant increase of spring germination in c. 30% of the species and elicited autumn germination in 50%. When heat waves were coupled with drought, seed germination decreased in all species, but did not stop completely. Our results suggest that in the future, heat waves will affect the germination phenology of alpine plants, especially conditionally dormant and strictly cold-adapted chorotypes, by shifting the emergence time from spring to autumn and by increasing the proportion of emerged seedlings. The detrimental effects of heat waves on recruitment success is less likely to be due to the inhibition of seed germination per se, but rather due to seedling survival in seasons, and temperature and water conditions that they are not used to experiencing. Changes in the proportion and timing of emergence

  16. Field-effect Flow Control in Polymer Microchannel Networks

    NASA Technical Reports Server (NTRS)

    Sniadecki, Nathan; Lee, Cheng S.; Beamesderfer, Mike; DeVoe, Don L.

    2003-01-01

    A new Bio-MEMS electroosmotic flow (EOF) modulator for plastic microchannel networks has been developed. The EOF modulator uses field-effect flow control (FEFC) to adjust the zeta potential at the Parylene C microchannel wall. By setting a differential EOF pumping rate in two of the three microchannels at a T-intersection with EOF modulators, the induced pressure at the intersection generated pumping in the third, field-free microchannel. The EOF modulators are able to change the magnitude and direction of the pressure pumping by inducing either a negative or positive pressure at the intersection. The flow velocity is tracked by neutralized fluorescent microbeads in the microchannels. The proof-of-concept of the EOF modulator described here may be applied to complex plastic ,microchannel networks where individual microchannel flow rates are addressable by localized induced-pressure pumping.

  17. Spanish Network on Effects of Wildfires on Soils. The view after 5 years of networking

    NASA Astrophysics Data System (ADS)

    Jordán, Antonio; Mataix-Solera, Jorge; Cerdà, Artemi

    2013-04-01

    1. WHAT IS FUEGORED? The Spanish Thematic Network "Effects of Wildfires on Soils" (FUEGORED, http://grupo.us.es/fuegored) has been working for over 5 years at becoming a point of reference for the study of fire-affected soils and restoration strategies. FUEGORED started in 2007, originally scheduled to run three years, as a result of the interest of Spanish researchers for developing better strategies and scientific interchange of ideas, people and collaboration between research groups. The first steps towards the establishment of a working group were a series of fieldtrips through Spain (2003), USA (2004) and Portugal (2005), where discussions about problems and research strategies arised. In its early years the network was supported by the former Ministry of Science and Innovation. This is a project to review scientific knowledge developed to date and discuss and propose future developments in scientific research about the effects of wildfires on soils. The objectives of the network are to promote and disseminate scientific research findings, provide technical and management information, and facilitate transference of knowledge between scientists, forest managers, students and society. 2. WHO IS IN THE NETWORK? The research group consists of the leading names of Spanish science in the topic and young talents, which are currently developing the most innovative research lines. Currently, the network is formed by 245 members, researchers from over 30 Spanish universities and research centers to provide the experience of decades of scientific and technical work in areas affected by forest fires and outstanding foreign researchers from Europe, Australia and America, including countries such as Australia, Italy, Lithuania, Portugal, UK, USA and others. Forest managers and technicians from various institutions are also present. 3. MAIN ACHIEVEMENTS Four international congresses have been promoted by the network in Valencia, 2008, Seville, 2009, Santiago de Compostela

  18. QTL for the thermotolerance effect of heat hardening, knockdown resistance to heat and chill-coma recovery in an intercontinental set of recombinant inbred lines of Drosophila melanogaster.

    PubMed

    Norry, Fabian M; Scannapieco, Alejandra C; Sambucetti, Pablo; Bertoli, Carlos I; Loeschcke, Volker

    2008-10-01

    The thermotolerance effect of heat hardening (also called short-term acclimation), knockdown resistance to high temperature (KRHT) with and without heat hardening and chill-coma recovery (CCR) are important phenotypes of thermal adaptation in insects and other organisms. Drosophila melanogaster from Denmark and Australia were previously selected for low and high KRHT, respectively. These flies were crossed to construct recombinant inbred lines (RIL). KRHT was higher in heat-hardened than in nonhardened RIL. We quantify the heat-hardening effect (HHE) as the ratio in KRHT between heat-hardened and nonhardened RIL. Composite interval mapping revealed a more complex genetic architecture for KRHT without heat-hardening than for KRHT in heat-hardened insects. Five quantitative trait loci (QTL) were found for KRHT, but only two of them were significant after heat hardening. KRHT and CCR showed trade-off associations for QTL both in the middle of chromosome 2 and the right arm of chromosome 3, which should be the result of either pleiotropy or linkage. The major QTL on chromosome 2 explained 18% and 27-33% of the phenotypic variance in CCR and KRHT in nonhardened flies, respectively, but its KRHT effects decreased by heat hardening. We discuss candidate loci for each QTL. One HHE-QTL was found in the region of small heat-shock protein genes. However, HHE-QTL explained only a small fraction of the phenotypic variance. Most heat-resistance QTL did not colocalize with CCR-QTL. Large-effect QTL for CCR and KRHT without hardening (basal thermotolerance) were consistent across continents, with apparent transgressive segregation for CCR. HHE (inducible thermotolerance) was not regulated by large-effect QTL.

  19. Effects of heat treatment of wood on hydroxylapatite type mineral precipitation and biomechanical properties in vitro.

    PubMed

    Rekola, J; Lassila, L V J; Hirvonen, J; Lahdenperä, M; Grenman, R; Aho, A J; Vallittu, P K

    2010-08-01

    Wood is a natural fiber reinforced composite. It structurally resembles bone tissue to some extent. Specially heat-treated birch wood has been used as a model material for further development of synthetic fiber reinforced composites (FRC) for medical and dental use. In previous studies it has been shown, that heat treatment has a positive effect on the osteoconductivity of an implanted wood. In this study the effects of two different heat treatment temperatures (140 and 200 degrees C) on wood were studied in vitro. Untreated wood was used as a control material. Heat treatment induced biomechanical changes were studied with flexural and compressive tests on dry birch wood as well as on wood after 63 days of simulated body fluid (SBF) immersion. Dimensional changes, SBF sorption and hydroxylapatite type mineral formation were also assessed. The results showed that SBF immersion decreases the biomechanical performance of wood and that the heat treatment diminishes the effect of SBF immersion on biomechanical properties. With scanning electron microscopy and energy dispersive X-ray analysis it was shown that hydroxylapatite type mineral precipitation formed on the 200 degrees C heat-treated wood. An increased weight gain of the same material during SBF immersion supported this finding. The results of this study give more detailed insight of the biologically relevant changes that heat treatment induces in wood material. Furthermore the findings in this study are in line with previous in vivo studies.

  20. The effect of heat treatment on the morphology of D-Gun sprayed hydroxyapatite coatings.

    PubMed

    Erkmen, Z E

    1999-01-01

    In this study, the morphology of the Hydroxyapatite (HA) coatings sprayed on Ti alloy samples by Detonation Gun Spray (D-Gun) and the effect of aging before and after heat treatment in physiological solution were observed. Cross-sectional porosity and percentages of amorphous and crystal phase were measured using optical, electron microscopy, and X-ray diffraction analysis. Differential Thermogravimetric Analysis (DTA) was performed to estimate the glass-crystalline phase transformation temperatures. Heat-treatment at 300, 500, 700, 800 and 1200 degrees C were carried out to confirm DTA results. As a final analysis, the aging effect using Ringer's solution for 1 week on heat-treated and non-heat-treated samples was measured. It was observed that, in D-Gun sprayed samples, the cross-sectional porosity stayed in the accepted 5% range as reported for other spraying techniques.(1-5) On the other hand, surface porosity measured using the water immersion method remained in the conventional porosity limit of 15% for non-heat-treated samples. Heat-treatment had a small influence on the porosity while the crystallinity increased considerably; in addition, aging had little effect on HA crystallinity for heat treated samples. This work showed that D-gun sprayed HA coatings had lower porosity and better integrity than other coatings, due to which we can expect better performance during in vivo applications.

  1. Effect of water on the heat capacity of polymerized aluminosilicate glasses and melts

    NASA Astrophysics Data System (ADS)

    Bouhifd, M. Ali; Whittington, Alan; Roux, Jacques; Richet, Pascal

    2006-02-01

    The effect of water on heat capacity has been determined for four series of hydrated synthetic aluminosilicate glasses and supercooled liquids close to albite, phonolite, trachyte, and leucogranite compositions. Heat capacities were measured at atmospheric pressure by differential scanning calorimetry for water contents between 0 and 4.9 wt % from 300 K to about 100 K above the glass transition temperature ( Tg). The partial molar heat capacity of water in polymerized aluminosilicate glasses, which can be considered as independent of composition, is =-122.319+341.631×10-3T+63.4426×105/T2 (J/mol K). In liquids containing at least 1 wt % H 2O, the partial molar heat capacity of water is about 85 J/mol K. From speciation data, the effects of water as hydroxyl groups and as molecular water have tentatively been estimated, with partial molar heat capacities of 153 ± 18 and 41 ± 14 J/mol K, respectively. In all cases, water strongly increases the configurational heat capacity at Tg and exerts a marked depressing effect on Tg, in close agreement with the results of viscosity experiments on the same series of glasses. Consistent with the Adam and Gibbs theory of relaxation processes, the departure of the viscosity of hydrous melts from Arrhenian variations correlates with the magnitude of configurational heat capacities.

  2. Effect of heat on firefighters' work performance and physiology.

    PubMed

    Larsen, Brianna; Snow, Rodney; Aisbett, Brad

    2015-10-01

    Wildland firefighters often perform their duties under both hot and mild ambient temperatures. However, the direct impact of different ambient temperatures on firefighters' work performance has not been quantified. This study compared firefighters' work performance and physiology during simulated wildland firefighting work in hot (HOT; 32°C, 43% RH) and temperate (CON; 19°C, 56% RH) conditions. Firefighters (n=38), matched and allocated to either the CON (n=18) or HOT (n=20) condition, performed simulated self-paced wildland fire suppression tasks (e.g., hose rolling/dragging, raking) in firefighting clothing for six hours, separated by dedicated rest breaks. Task repetitions were counted (and converted to distance or area). Core temperature (Tc), skin temperature (Tsk), and heart rate were recorded continuously throughout the protocol. Urine output was measured before and during the protocol, and urine specific gravity (USG) analysed, to estimate hydration. Ad libitum fluid intake was also recorded. There were no differences in overall work output between conditions for any physical task. Heart rate was higher in the HOT (55±2% HRmax) compared to the CON condition (51±2% HRmax) for the rest periods between bouts, and for the static hose hold task (69±3% HRmax versus 65±3% HRmax). Tc and Tsk were 0.3±0.1°C and 3.1±0.2°C higher in the HOT compared to the CON trial. Both pre- and within- shift fluid intake were increased two-fold in the heat, and participants in the heat recorded lower USG results than their CON counterparts. There was no difference between the CON and HOT conditions in terms of their work performance, and firefighters in both experimental groups increased their work output over the course of the simulated shift. Though significantly hotter, participants in the heat also managed to avoid excessive cardiovascular and thermal strain, likely aided by the frequent rest breaks in the protocol, and through doubling their fluid intake. Therefore

  3. Effect of alkali and heat treatments for bioactivity of TiO2 nanotubes

    NASA Astrophysics Data System (ADS)

    Kim, Seo young; Kim, Yu kyoung; Park, Il song; Jin, Guang chun; Bae, Tae sung; Lee, Min ho

    2014-12-01

    In this study, for improving the bioactivity of titanium used as an implant material, alkali and heat treatments were carried out after formation of the nanotubes via anodization. Nanotubes with uniform length, diameter, and thickness were formed by anodization. The alkali and heat-treated TiO2 nanotubes were covered with the complex network structure, and the Na compound was generated on the surface of the specimens. In addition, after 5 and 10 days of immersion in the SBF, the crystallized OCP and HAp phase was significantly increased on the surface of the alkali-treated TiO2 nanotubes (PNA) and alkali and heat-treated TiO2 nanotubes (PNAH) groups. Cell proliferation was decreased due to the formation of amorphous sodium titanate (Na2TiO3) layer on the surface of the PNA group. However, anatase and crystalline sodium titanate were formed on the surface of the PNAH group after heat treatment at 550 °C, and cell proliferation was improved. Thus, PNA group had higher HAp forming ability in the simulated body fluid. Additional heat treatment affected on enhancement of the bioactivity and the attachment of osteoblasts for PNA group.

  4. Evaluation of the plan for surveillance and controlling of the effects of heat waves in Madrid

    NASA Astrophysics Data System (ADS)

    Culqui, Dante R.; Diaz, Julio; Simón, Fernando; Tobías, Aurelio; Linares, Cristina

    2014-10-01

    This paper presents evaluation of a plan for surveillance of and controlling the effects of heat-related mortality (PSCEHW), implemented in Madrid in 2004 through a time series analysis conducted with ARIMA modeling. From the public health point of view, prevention plans should be implemented as adaptive measures to heat waves. In 2003, the impact attributable to the heat wave was an increase in mortality per °C of 22.39 %. All heat waves since 2003 have been of lower intensity, and yet, in 2005 there was a heat wave of lower intensity that had a greater impact, i.e. an increase in mortality per °C of 45.71 %. With the methodology used here, we cannot say whether implementation of PSCEHW has resulted in a decrease of mortality attributable to high temperatures in the city of Madrid.

  5. A mathematical analysis of heating effects and electrode erosion in conical electrical arc cathodes

    NASA Astrophysics Data System (ADS)

    Solana, Pablo; Kapadia, Phiroze; Dowden, John

    1998-12-01

    A spherical system of coordinates is used to solve the time-dependent heat-conduction equation for inside a conical cathode, whose surface is subjected, during arc welding processes, to complicated thermal heat-exchange effects. These arise from a variety of factors such as ion bombardment from the main body of the electrical arc, thermionic emission from the cathode's surface and Joule heating arising from the main current-carrying body of the cathode. The heat-conduction equation has a time-dependent source term arising from a combination of Joule heating and thermionic emission and is solved analytically using integral transform techniques. The solution is expressed in terms of integrals. These allow the response of the cathode for various currents and cathode geometries to be studied.

  6. The effects of heat treatment on some technological properties of Scots pine (Pinus sylvestris L.) wood.

    PubMed

    Korkut, Süleyman; Akgül, Mehmet; Dündar, Turker

    2008-04-01

    Heat treatment is often applied to wood species to improve their dimensional stability. This study examined the effect of heat treatment on certain mechanical properties of Scots pine (Pinus sylvestris L.), which has industrially high usage potential and large plantations in Turkey. Wood specimens obtained from Bolu, Turkey, were subjected to heat treatment under atmospheric pressure at varying temperatures (120, 150 and 180 degrees C) for varying durations (2, 6 and 10h). The test results of heat-treated Scots pine and control samples showed that technological properties including compression strength, bending strength, modulus of elasticity in bending, janka-hardness, impact bending strength and tension strength perpendicular to grain suffered with heat treatment, and increase in temperature and duration further diminished technological strength values of the wood specimens.

  7. Decoupling electrocaloric effect from Joule heating in a solid state cooling device

    NASA Astrophysics Data System (ADS)

    Quintero, M.; Ghivelder, L.; Gomez-Marlasca, F.; Parisi, F.

    2011-12-01

    We report a heat dynamics analysis of the electrocaloric effect (ECE) in commercial multilayer capacitors based on BaTiO3 dielectric, a promising candidate for applications as a solid state cooling device. Direct measurements of the time evolution of the sample's temperature changes under different applied voltages allow us to decouple the contributions from Joule heating and from the ECE. Heat balance equations were used to model the thermal coupling between different parts of the system. Fingerprints of Joule heating and the ECE could be resolved at different time scales. We argue that Joule heating and the thermal coupling of the device to the environment must be carefully taken in to account in future developments of refrigeration technologies employing the ECE.

  8. The effects of heat treatment on some technological properties of Scots pine (Pinus sylvestris L.) wood.

    PubMed

    Korkut, Süleyman; Akgül, Mehmet; Dündar, Turker

    2008-04-01

    Heat treatment is often applied to wood species to improve their dimensional stability. This study examined the effect of heat treatment on certain mechanical properties of Scots pine (Pinus sylvestris L.), which has industrially high usage potential and large plantations in Turkey. Wood specimens obtained from Bolu, Turkey, were subjected to heat treatment under atmospheric pressure at varying temperatures (120, 150 and 180 degrees C) for varying durations (2, 6 and 10h). The test results of heat-treated Scots pine and control samples showed that technological properties including compression strength, bending strength, modulus of elasticity in bending, janka-hardness, impact bending strength and tension strength perpendicular to grain suffered with heat treatment, and increase in temperature and duration further diminished technological strength values of the wood specimens. PMID:17482811

  9. Heating effect on physical and electrochemical properties of nanofibrous polyacrylonitrile separator for lithium batteries.

    PubMed

    Woo, Jang Chang; Youk, Ji Ho; Kim, Dul-Sun; Ahn, Jou-Hyeon

    2014-12-01

    Nanofibrous polyacrylonitrile (PAN) membranes as nonwoven separators were prepared by electrospinning followed by a thermal treatment to improve their physical properties. The effect of the thermal treatment on the physical and electrochemical properties of the PAN separators was investigated. With increasing heating time, the PAN nanofiber separators became denser with decreasing size of fully interconnected pores. The tensile strength and modulus of the nanofibrous PAN separators varied with the heating temperature and heating time. The maximum tensile strength and modulus were obtained at a heating temperature and heating time of 170 degrees C and 5 h, respectively. The cell assembled with the PAN separator prepared at 170 degrees C for 5 h exhibited high capacity retention and stable cycle performance, even at higher discharge current densities. PMID:25971042

  10. Effective-medium model of wire metamaterials in the problems of radiative heat transfer

    SciTech Connect

    Mirmoosa, M. S. Nefedov, I. S. Simovski, C. R.; Rüting, F.

    2014-06-21

    In the present work, we check the applicability of the effective medium model (EMM) to the problems of radiative heat transfer (RHT) through so-called wire metamaterials (WMMs)—composites comprising parallel arrays of metal nanowires. It is explained why this problem is so important for the development of prospective thermophotovoltaic (TPV) systems. Previous studies of the applicability of EMM for WMMs were targeted by the imaging applications of WMMs. The analogous study referring to the transfer of radiative heat is a separate problem that deserves extended investigations. We show that WMMs with practically realizable design parameters transmit the radiative heat as effectively homogeneous media. Existing EMM is an adequate tool for qualitative prediction of the magnitude of transferred radiative heat and of its effective frequency band.

  11. Dietary chromium methionine supplementation could alleviate immunosuppressive effects of heat stress in broiler chicks.

    PubMed

    Jahanian, R; Rasouli, E

    2015-07-01

    The present study was conducted to investigate the effects of dietary supplementation of chromium methionine (CrMet) on performance, immune responses, and stress status of broiler chicks subjected to heat-stress conditions. A total of 450 day-old Ross 308 broiler chicks were randomly distributed between 5 replicate pens (15 birds each) of 6 experimental treatments according to a 2 × 3 factorial arrangement of treatments including 2 temperature conditions (thermoneutral and heat stress) and 3 supplemental Cr levels (0, 500, and 1,000 μg/kg as CrMet). For induction of heat stress, the house temperature was set at 35 ± 2°C from 15 to 42 d of age. Results showed that the chicks subjected to heat-stress condition had lower (P < 0.01) feed intake, BW gain, and deteriorated (P < 0.05) feed conversion values compared with those kept in the thermoneutral house. Dietary supplementation with CrMet increased (P < 0.01) feed intake and improved (P < 0.01) weight gain and feed efficiency. There were significant Cr level × temperature interactions, so that inclusion of CrMet into the diets was more effective in heat-stressed chicks. Exposure to heat stress suppressed (P < 0.01) cutaneous hypersensivity response to phytohemagglutinin-P injection at 30 d of age, and dietary supplementation of 500 μg Cr/kg induced (P < 0.05) this response, with the greater impacts in heat-stressed chicks, resulting in a significant (P < 0.01) Cr × temperature interaction. Antibody responses against Newcastle and infectious bronchitis disease viruses were diminished (P < 0.01) in heat-stressed chicks. Dietary inclusion of CrMet improved (P < 0.05) antibody responses to different immunostimulants, and this effect was more pronounced in heat-stressed chicks. Exposure to heat stress caused a significant (P < 0.05) decrease in the proportion of helper (CD4+) T lymphocytes and increased cytotoxic (CD8+) T lymphocytes, resulting in a decreased (P < 0.01) CD4+ to CD8+ ratio in peripheral blood

  12. Effect of Heat on Space-Time Correlations in Jets

    NASA Technical Reports Server (NTRS)

    Bridges, James

    2006-01-01

    Measurements of space-time correlations of velocity, acquired in jets from acoustic Mach number 0.5 to 1.5 and static temperature ratios up to 2.7 are presented and analyzed. Previous reports of these experiments concentrated on the experimental technique and on validating the data. In the present paper the dataset is analyzed to address the question of how space-time correlations of velocity are different in cold and hot jets. The analysis shows that turbulent kinetic energy intensities, lengthscales, and timescales are impacted by the addition of heat, but by relatively small amounts. This contradicts the models and assumptions of recent aeroacoustic theory trying to predict the noise of hot jets. Once the change in jet potential core length has been factored out, most one- and two-point statistics collapse for all hot and cold jets.

  13. Acute effects of heat on neuropsychological changes and physiological responses under noise condition.

    PubMed

    Bhattacharya, S K; Tripathi, S R; Pradhan, C K; Kashyap, S K

    1990-09-01

    To examine the effects of heat and noise individually and jointly on certain physiological responses and cognitive and neuromotor based functions, 12 male participants were tested under 6 experimental conditions which resulted by combining 3 levels of heat (25 degrees, 30 degrees and 35 degrees C) and 2 levels of white noise (70 and 100 dB). The experiment was carried out in a controlled climatic chamber following two 6 x 6 latin square designs. The results indicated elevations in heart rate, oxygen uptake and body temperature due to the independent effect of heat or the combined effects of heat and noise. The independent action of noise was found to be depressive on the first two responses. On the neuropsychological effects, the heat adversely affected the speed in card sorting (by design configuration) and digit symbol tests, and also the accuracy and error rate in the reasoning ability test. The noise caused performance improvements in critical flicker frequency (simultaneous) and in error rates in card sorting (by design configuration). The combined effects of heat and noise indicated higher error rates in card sorting (by face value), decreased accuracy in reasoning ability and improvements in performance in accuracy scores and error rates in digit symbol test. PMID:2279778

  14. A mathematical model to predict the effect of heat recovery on the wastewater temperature in sewers.

    PubMed

    Dürrenmatt, David J; Wanner, Oskar

    2014-01-01

    Raw wastewater contains considerable amounts of energy that can be recovered by means of a heat pump and a heat exchanger installed in the sewer. The technique is well established, and there are approximately 50 facilities in Switzerland, many of which have been successfully using this technique for years. The planning of new facilities requires predictions of the effect of heat recovery on the wastewater temperature in the sewer because altered wastewater temperatures may cause problems for the biological processes used in wastewater treatment plants and receiving waters. A mathematical model is presented that calculates the discharge in a sewer conduit and the spatial profiles and dynamics of the temperature in the wastewater, sewer headspace, pipe, and surrounding soil. The model was implemented in the simulation program TEMPEST and was used to evaluate measured time series of discharge and temperatures. It was found that the model adequately reproduces the measured data and that the temperature and thermal conductivity of the soil and the distance between the sewer pipe and undisturbed soil are the most sensitive model parameters. The temporary storage of heat in the pipe wall and the exchange of heat between wastewater and the pipe wall are the most important processes for heat transfer. The model can be used as a tool to determine the optimal site for heat recovery and the maximal amount of extractable heat.

  15. The effect of heating rate on the surface chemistry of NiTi.

    PubMed

    Undisz, Andreas; Hanke, Robert; Freiberg, Katharina E; Hoffmann, Volker; Rettenmayr, Markus

    2014-11-01

    The impact of the heating rate on the Ni content at the surface of the oxide layer of biomedical NiTi is explored. Heat treatment emulating common shape-setting procedures was performed by means of conventional and inductive heating for similar annealing time and temperature, applying various heating rates from ~0.25 K s(-1) to 250 K s(-1). A glow discharge optical emission spectroscopy method was established and employed to evaluate concentration profiles of Ni, Ti and O in the near-surface region at high resolution. The Ni content at the surface of the differently treated samples varies significantly, with maximum surface Ni concentrations of ~20 at.% at the lowest and ~1.5 at.% at the highest heating rate, i.e. the total amount of Ni contained in the surface region of the oxide layer decreases by >15 times. Consequently, the heating rate is a determinant for the biomedical characteristics of NiTi, especially since Ni available at the surface of the oxide layer may affect the hemocompatibility and be released promptly after surgical application of a respective implant. Furthermore, apparently contradictory results presented in the literature reporting surface Ni concentrations of ~3 at.% to >20 at.% after heat treatment are consistently explained considering the ascertained effect of the heating rate.

  16. Effects of several factors on the heat-shock-induced thermotolerance of Listeria monocytogenes.

    PubMed Central

    Pagán, R; Condón, S; Sala, F J

    1997-01-01

    The influence of the temperature at which Listeria monocytogenes had been grown (4 or 37 degrees C) on the response to heat shocks of different durations at different temperatures was investigated. For cells grown at 4 degrees C, the effect of storage, prior to and after heat shock, on the induced thermotolerance was also studied. Death kinetics of heat-shocked cells is also discussed. For L. monocytogenes grown at 37 degrees C, the greatest response to heat shock was a fourfold increase in thermotolerance. For L. monocytogenes grown at 4 degrees C, the greatest response to heat shock was a sevenfold increase in thermotolerance. The only survival curves of cells to have shoulders were those for cells that had been heat shocked. A 3% concentration of sodium chloride added to the recovery medium made these shoulders disappear and decreased decimal reduction times. The percentage of cells for which thermotolerance increased after a heat shock was smaller the milder the heat shock and the longer the prior storage. PMID:9251209

  17. A mathematical model to predict the effect of heat recovery on the wastewater temperature in sewers.

    PubMed

    Dürrenmatt, David J; Wanner, Oskar

    2014-01-01

    Raw wastewater contains considerable amounts of energy that can be recovered by means of a heat pump and a heat exchanger installed in the sewer. The technique is well established, and there are approximately 50 facilities in Switzerland, many of which have been successfully using this technique for years. The planning of new facilities requires predictions of the effect of heat recovery on the wastewater temperature in the sewer because altered wastewater temperatures may cause problems for the biological processes used in wastewater treatment plants and receiving waters. A mathematical model is presented that calculates the discharge in a sewer conduit and the spatial profiles and dynamics of the temperature in the wastewater, sewer headspace, pipe, and surrounding soil. The model was implemented in the simulation program TEMPEST and was used to evaluate measured time series of discharge and temperatures. It was found that the model adequately reproduces the measured data and that the temperature and thermal conductivity of the soil and the distance between the sewer pipe and undisturbed soil are the most sensitive model parameters. The temporary storage of heat in the pipe wall and the exchange of heat between wastewater and the pipe wall are the most important processes for heat transfer. The model can be used as a tool to determine the optimal site for heat recovery and the maximal amount of extractable heat. PMID:24216228

  18. Effect of flue gas recirculation on heat transfer in a supercritical circulating fluidized bed combustor

    NASA Astrophysics Data System (ADS)

    Błaszczuk, Artur

    2015-09-01

    This paper focuses on assessment of the effect of flue gas recirculation (FGR) on heat transfer behavior in 1296t/h supercritical coal-fired circulating fluidized bed (CFB) combustor. The performance test in supercritical CFB combustor with capacity 966 MWth was performed with the low level of flue gas recirculation rate 6.9% into furnace chamber, for 80% unit load at the bed pressure of 7.7 kPa and the ratio of secondary air to the primary air SA/PA = 0.33. Heat transfer behavior in a supercritical CFB furnace between the active heat transfer surfaces (membrane wall and superheater) and bed material has been analyzed for Geldart B particle with Sauter mean diameters of 0.219 and 0.246 mm. Bed material used in the heat transfer experiments had particle density of 2700 kg/m3. A mechanistic heat transfer model based on cluster renewal approach was used in this work. A heat transfer analysis of CFB combustion system with detailed consideration of bed-to-wall heat transfer coefficient distributions along furnace height is investigated. Heat transfer data for FGR test were compared with the data obtained for representative conditions without recycled flue gases back to the furnace through star-up burners.

  19. Effect of heating rate on intercritical annealing of low-carbon cold-rolled steel

    NASA Astrophysics Data System (ADS)

    Thomas, Larrin

    A study was performed on the effect of heating rate on transformations during intercritical annealing of cold-rolled low-carbon sheet steels. Two sets of experiments were developed: 1) a series of alloys (1020, 1019M, 15B25) with two different cold reductions (nominally 40 and 60 pct) were heated at different rates and transformation temperatures were determined using analysis of dilatometry and metallography of intercritically annealed samples, allowing the study of the impact of composition and cold work on transformation behavior with different heating rates. 2) A cold-rolled C-Mn-Nb steel was tested with different heating rates selected for different degrees of recrystallization during austenite formation to test the impact of ferrite recrystallization on austenite formation. Heat treated samples were analyzed with SEM, EBSD, dilatometry, and microhardness to study the changes in transformation behavior. The results of this study were extended by adding step heating tests, heat treatments with an intercritical hold, and secondary ion mass spectrometry (SIMS) measurements of Mn distribution. Austenite transformation temperatures increased logarithmically with heating rate. Greater degrees of cold work led to reduced transformation temperatures across all heating rates because the energy of cold work increased the driving force for austenite formation. The relative effects of alloying additions on transformation temperatures remained with increasing heating rate. Rapid heating minimized ferrite recrystallization and pearlite spheroidization. Austenite formation occurred preferentially in recovered ferrite regions as opposed to recrystallized ferrite boundaries. Martensite was evenly distributed in slowly heated steels because austenite formed on recrystallized, equiaxed, ferrite boundaries. With rapid heating, austenite formed in directionally-oriented recovered ferrite which increased the degree of banding. The greatest degree of banding was found with

  20. Multiplatform analysis of the radiative effects and heating rates for an intense dust storm on 21 June 2007

    NASA Astrophysics Data System (ADS)

    Naeger, Aaron R.; Christopher, Sundar A.; Johnson, Ben T.

    2013-08-01

    Dust radiative effects and atmospheric heating rates are investigated for a Saharan dust storm on 21 June 2007 using a combination of multiple satellite data sets and ground and aircraft observations as input into a delta-four stream radiative transfer model (RTM). This combines the strengths of the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations and CloudSat satellites and in situ aircraft data to characterize the vertical structure of the dust layers (5 km in height with optical depths between 1.5 and 2.0) and underlying low-level water clouds. These observations were used, along with Aerosol Robotic Network retrievals of aerosol optical properties, as input to the RTM to assess the surface, atmosphere, and top of atmosphere (TOA) shortwave aerosol radiative effects (SWAREs). Our results show that the dust TOA SWARE per unit aerosol optical depth was -56 W m-2 in cloud-free conditions over ocean and +74 W m-2 where the dust overlay low-level clouds, and show heating rates greater than 10 K/d. Additional case studies also confirm the results of the 21 June case. This study shows the importance of identifying clouds beneath dust as they can have a significant impact on the radiative effects of dust, and hence assessments of the role of dust aerosol on the energy budget and climate.

  1. The effect of external heat transfer on thermal explosion in a spherical vessel with natural convection.

    PubMed

    Campbell, A N

    2015-07-14

    When any exothermic reaction proceeds in an unstirred vessel, natural convection may develop. This flow can significantly alter the heat transfer from the reacting fluid to the environment and hence alter the balance between heat generation and heat loss, which determines whether or not the system will explode. Previous studies of the effects of natural convection on thermal explosion have considered reactors where the temperature of the wall of the reactor is held constant. This implies that there is infinitely fast heat transfer between the wall of the vessel and the surrounding environment. In reality, there will be heat transfer resistances associated with conduction through the wall of the reactor and from the wall to the environment. The existence of these additional heat transfer resistances may alter the rate of heat transfer from the hot region of the reactor to the environment and hence the stability of the reaction. This work presents an initial numerical study of thermal explosion in a spherical reactor under the influence of natural convection and external heat transfer, which neglects the effects of consumption of reactant. Simulations were performed to examine the changing behaviour of the system as the intensity of convection and the importance of external heat transfer were varied. It was shown that the temporal development of the maximum temperature in the reactor was qualitatively similar as the Rayleigh and Biot numbers were varied. Importantly, the maximum temperature in a stable system was shown to vary with Biot number. This has important consequences for the definitions used for thermal explosion in systems with significant reactant consumption. Additionally, regions of parameter space where explosions occurred were identified. It was shown that reducing the Biot number increases the likelihood of explosion and reduces the stabilising effect of natural convection. Finally, the results of the simulations were shown to compare favourably with

  2. Study on modeling of resist heating effect correction in EB mask writer EBM-9000

    NASA Astrophysics Data System (ADS)

    Nomura, Haruyuki; Kamikubo, Takashi; Suganuma, Mizuna; Kato, Yasuo; Yashima, Jun; Nakayamada, Noriaki; Anze, Hirohito; Ogasawara, Munehiro

    2015-07-01

    Resist heating effect which is caused in electron beam lithography by rise in substrate temperature of a few tens or hundreds of degrees changes resist sensitivity and leads to degradation of local critical dimension uniformity (LCDU). Increasing writing pass count and reducing dose per pass is one way to avoid the resist heating effect, but it worsens writing throughput. As an alternative way, NuFlare Technology is developing a heating effect correction system which corrects CD deviation induced by resist heating effect and mitigates LCDU degradation even in high dose per pass conditions. Our developing correction model is based on a dose modulation method. Therefore, a kind of conversion equation to modify the dose corresponding to CD change by temperature rise is necessary. For this purpose, a CD variation model depending on local pattern density was introduced and its validity was confirmed by experiments and temperature simulations. And then the dose modulation rate which is a parameter to be used in the heating effect correction system was defined as ideally irrelevant to the local pattern density, and the actual values were also determined with the experimental results for several resist types. The accuracy of the heating effect correction was also discussed. Even when deviations depending on the pattern density slightly remains in the dose modulation rates (i.e., not ideal in actual), the estimated residual errors in the correction are sufficiently small and acceptable for practical 2 pass writing with the constant dose modulation rates. In these results, it is demonstrated that the CD variation model is effective for the heating effect correction system.

  3. Lattice Boltzmann modeling of boiling heat transfer: The boiling curve and the effects of wettability

    SciTech Connect

    Li, Q.; Kang, Q. J.; Francois, M. M.; He, Y. L.; Luo, K. H.

    2015-03-03

    A hybrid thermal lattice Boltzmann (LB) model is presented to simulate thermal multiphase flows with phase change based on an improved pseudopotential LB approach (Li et al., 2013). The present model does not suffer from the spurious term caused by the forcing-term effect, which was encountered in some previous thermal LB models for liquid–vapor phase change. Using the model, the liquid–vapor boiling process is simulated. The boiling curve together with the three boiling stages (nucleate boiling, transition boiling, and film boiling) is numerically reproduced in the LB community for the first time. The numerical results show that the basic features and the fundamental characteristics of boiling heat transfer are well captured, such as the severe fluctuation of transient heat flux in the transition boiling and the feature that the maximum heat transfer coefficient lies at a lower wall superheat than that of the maximum heat flux. Moreover, the effects of the heating surface wettability on boiling heat transfer are investigated. It is found that an increase in contact angle promotes the onset of boiling but reduces the critical heat flux, and makes the boiling process enter into the film boiling regime at a lower wall superheat, which is consistent with the findings from experimental studies.

  4. Lattice Boltzmann modeling of boiling heat transfer: The boiling curve and the effects of wettability

    DOE PAGESBeta

    Li, Q.; Kang, Q. J.; Francois, M. M.; He, Y. L.; Luo, K. H.

    2015-03-03

    A hybrid thermal lattice Boltzmann (LB) model is presented to simulate thermal multiphase flows with phase change based on an improved pseudopotential LB approach (Li et al., 2013). The present model does not suffer from the spurious term caused by the forcing-term effect, which was encountered in some previous thermal LB models for liquid–vapor phase change. Using the model, the liquid–vapor boiling process is simulated. The boiling curve together with the three boiling stages (nucleate boiling, transition boiling, and film boiling) is numerically reproduced in the LB community for the first time. The numerical results show that the basic featuresmore » and the fundamental characteristics of boiling heat transfer are well captured, such as the severe fluctuation of transient heat flux in the transition boiling and the feature that the maximum heat transfer coefficient lies at a lower wall superheat than that of the maximum heat flux. Moreover, the effects of the heating surface wettability on boiling heat transfer are investigated. It is found that an increase in contact angle promotes the onset of boiling but reduces the critical heat flux, and makes the boiling process enter into the film boiling regime at a lower wall superheat, which is consistent with the findings from experimental studies.« less

  5. Orientational effects on the performance of a heat pipe coupled thermionic converter

    NASA Astrophysics Data System (ADS)

    Young, Timothy J.; Ramalingam, Mysore L.; Tsao, Bang-Hung

    The effects of collector heat pipe orientation on the electrical and thermal performance of a planar thermionic converter were examined. The planar thermionic converter under consideration is based on chemical-vapor-deposited rhenium on molybdenum electrodes, a separately heated two-phase cesium reservoir, and a radiantly coupled electric emitter heater. The converter fixture places the heat pipe in the reflux mode and makes it possible to change orientation at 15, 30, 45, and 60 degrees from the vertical. It was found that, in the range of 0-60 deg, the thermionic output performance is a relatively weak function of the orientation angle. The orientation effect on the converter performance increases with the increase of the emitter temperature. The difference in the temperatures of the heat pipe evaporator and condenser increases with increasing angle of inclination from the vertical. A safe operation region of the heat pipe with respect to heat input and tilt angle is determined by instabilities due to lack of heat throughput and inability to reprime the wick.

  6. Testing of a scanning adiabatic calorimeter with Joule effect heating of the sample

    NASA Astrophysics Data System (ADS)

    Barreiro-Rodríguez, G.; Yáñez-Limón, J. M.; Contreras-Servin, C. A.; Herrera-Gomez, A.

    2008-01-01

    We evaluated a scanning adiabatic resistive calorimeter (SARC) developed to measure the specific enthalpy of viscous and gel-type materials. The sample is heated employing the Joule effect. The cell is constituted by a cylindrical jacket and two pistons, and the sample is contained inside the jacket between the two pistons. The upper piston can slide to allow for thermal expansion and to keep the pressure constant. The pistons also function as electrodes for the sample. While the sample is heated through the Joule effect, the electrodes and the jacket are independently heated to the same temperature of the sample using automatic control. This minimizes the heat transport between the sample and its surroundings. The energy to the sample is supplied by applying to the electrodes an ac voltage in the kilohertz range, establishing a current in the sample and inducing electric dissipation. This energy can be measured with enough exactitude to determine the heat capacity. This apparatus also allows for the quantification of the thermal conductivity by reproducing the evolution of the temperature as heat is introduced only to one of the pistons. To this end, the system was modeled using finite element calculations. This dual capability proved to be very valuable for correction in the determination of the specific enthalpy. The performance of the SARC was evaluated by comparing the heat capacity results to those obtained by differential scanning calorimetry measurements using a commercial apparatus. The analyzed samples were zeolite, bauxite, hematite, bentonite, rice flour, corn flour, and potato starch.

  7. Heat conduction in a chain of dissociating particles: Effect of dimensionality

    NASA Astrophysics Data System (ADS)

    Zolotarevskiy, V.; Savin, A. V.; Gendelman, O. V.

    2015-03-01

    The paper considers heat conduction in a model chain of composite particles with hard core and elastic external shell. Such model mimics three main features of realistic interatomic potentials—hard repulsive core, quasilinear behavior in a ground state, and possibility of dissociation. It has become clear recently that this latter feature has crucial effect on convergence of the heat conduction coefficient in thermodynamic limit. We demonstrate that in one-dimensional chain of elastic particles with hard core the heat conduction coefficient also converges, as one could expect. Then we explore effect of dimensionality on the heat transport in this model. For this sake, longitudinal and transversal motions of the particles are allowed in a long narrow channel. With varying width of the channel, we observe sharp transition from "one-dimensional" to "two-dimensional" behavior. Namely, the heat conduction coefficient drops by about order of magnitude for relatively small widening of the channel. This transition is not unique for the considered system. Similar phenomenon of transition to quasi-1D behavior with growth of aspect ratio of the channel is observed also in a gas of densely packed hard (billiard) particles, both for two- and three-dimensional cases. It is the case despite the fact that the character of transition in these two systems is not similar, due to different convergence properties of the heat conductivity. In the billiard model, the divergence pattern of the heat conduction coefficient smoothly changes from logarithmic to power-like law with increase of the length.

  8. Effects of heat stress on serum insulin, adipokines, AMP-activated protein kinase, and heat shock signal molecules in dairy cows.

    PubMed

    Min, Li; Cheng, Jian-bo; Shi, Bao-lu; Yang, Hong-jian; Zheng, Nan; Wang, Jia-qi

    2015-06-01

    Heat stress affects feed intake, milk production, and endocrine status in dairy cows. The temperature-humidity index (THI) is employed as an index to evaluate the degree of heat stress in dairy cows. However, it is difficult to ascertain whether THI is the most appropriate measurement of heat stress in dairy cows. This experiment was conducted to investigate the effects of heat stress on serum insulin, adipokines (leptin and adiponectin), AMP-activated protein kinase (AMPK), and heat shock signal molecules (heat shock transcription factor (HSF) and heat shock proteins (HSP)) in dairy cows and to research biomarkers to be used for better understanding the meaning of THI as a bioclimatic index. To achieve these objectives, two experiments were performed. The first experiment: eighteen lactating Holstein dairy cows were used. The treatments were: heat stress (HS, THI average=81.7, n=9) and cooling (CL, THI average=53.4, n=9). Samples of HS were obtained on August 16, 2013, and samples of CL were collected on April 7, 2014 in natural conditions. The second experiment: HS treatment cows (n=9) from the first experiment were fed for 8 weeks from August 16, 2013 to October 12, 2013. Samples for moderate heat stress, mild heat stress, and no heat stress were obtained, respectively, according to the physical alterations of the THI. Results showed that heat stress significantly increased the serum adiponectin, AMPK, HSF, HSP27, HSP70, and HSP90 (P<0.05). Adiponectin is strongly associated with AMPK. The increases of adiponectin and AMPK may be one of the mechanisms to maintain homeostasis in heat-stressed dairy cows. When heat stress treatment lasted 8 weeks, a higher expression of HSF and HSP70 was observed under moderate heat stress. Serum HSF and HSP70 are sensitive and accurate in heat stress and they could be potential indicators of animal response to heat stress. We recommend serum HSF and HSP70 as meaningful biomarkers to supplement the THI and evaluate moderate heat

  9. Net benefits: assessing the effectiveness of clinical networks in Australia through qualitative methods

    PubMed Central

    2012-01-01

    Background In the 21st century, government and industry are supplementing hierarchical, bureaucratic forms of organization with network forms, compatible with principles of devolved governance and decentralization of services. Clinical networks are employed as a key health policy approach to engage clinicians in improving patient care in Australia. With significant investment in such networks in Australia and internationally, it is important to assess their effectiveness and sustainability as implementation mechanisms. Methods In two purposively selected, musculoskeletal clinical networks, members and stakeholders were interviewed to ascertain their perceptions regarding key factors relating to network effectiveness and sustainability. We adopted a three-level approach to evaluating network effectiveness: at the community, network, and member levels, across the network lifecycle. Results Both networks studied are advisory networks displaying characteristics of the ‘enclave’ type of non-hierarchical network. They are hybrids of the mandated and natural network forms. In the short term, at member level, both networks were striving to create connectivity and collaboration of members. Over the short to medium term, at network level, both networks applied multi-disciplinary engagement in successfully developing models of care as key outputs, and disseminating information to stakeholders. In the long term, at both community and network levels, stakeholders would measure effectiveness by the broader statewide influence of the network in changing and improving practice. At community level, in the long term, stakeholders acknowledged both networks had raised the profile, and provided a ‘voice’ for musculoskeletal conditions, evidencing some progress with implementation of the network mission while pursuing additional implementation strategies. Conclusions This research sheds light on stakeholders’ perceptions of assessing clinical network effectiveness at

  10. Effects of droplet velocity, diameter, and film height on heat removal during cryogen spray cooling.

    PubMed

    Pikkula, Brian M; Tunnell, James W; Chang, David W; Anvari, Bahman

    2004-08-01

    Cryogen spray cooling (CSC) is an effective method to reduce or eliminate epidermal damage during laser treatment of various dermatoses. This study sought to determine the effects of specific cryogen properties on heat removal. Heat removal was quantified using an algorithm that solved an inverse heat conduction problem from internal temperature measurements made within a skin phantom. A nondimensional parameter, the Weber number, characterized the combined effects of droplet velocity, diameter, and surface tension. CSC experiments with laser irradiation were conducted on ex vivo human skin samples to assess the effect of Weber number on epidermal protection. An empirical relationship between heat removal and the difference in droplet temperature and the substrate, droplet velocity, and diameter was obtained. Histological sections of irradiated ex vivo human skin demonstrated that sprays with higher Weber numbers increased epidermal protection. Results indicate that the cryogen film acts as an impediment to heat transfer between the impinging droplets and the substrate. This study offers the importance of Weber number in heat removal and epidermal protection. PMID:15446509

  11. The effect of rotation on heat transfer in the radial cooling channels of turbine blades

    NASA Astrophysics Data System (ADS)

    Iskakov, K. M.; Trushin, V. A.

    1985-02-01

    The effect of rotation on heat transfer in the channels of moving turbine blades in a loop cooling system is investigated experimentally. The working channels consisted of round tubes with sharp edges and the tubes were fixed to a support. Calculation of the parameters required for correlating the experimental data was conducted according to local air temperature at the entry of the channel. Analysis of the measured and calculated heat transfer parameters showed that the average error in determining heat transfer was 13 percent. The error in calculating the bulk flow rate of air was 8 percent. Formulas for calculating the centrifugal and centripetal air flows are derived.

  12. The Effect of Baffles on the Temperature Distribution and Heat-transfer Coefficients of Finned Cylinders

    NASA Technical Reports Server (NTRS)

    Schey, Oscar W; Rollin, Vern G

    1936-01-01

    This report presents the results of an investigation to determine the effect of baffles on the temperature distribution and the heat-transfer coefficient of finned cylinders. The tests were conducted in a 30-inch wind tunnel on electrically heated cylinders with fins of 0.25 and 0.31 inch pitch. The results of these tests showed that the use of integral baffles gave a reduction of 31.9 percent in the rear wall temperatures and an increase of 54.2 percent in the heat transfer coefficient as compared with a cylinder without baffles.

  13. Effect of horizontal heat and fluid flow on the vertical temperature distribution in a semiconfining layer

    USGS Publications Warehouse

    Lu, N.; Ge, S.

    1996-01-01

    By including the constant flow of heat and fluid in the horizontal direction, we develop an analytical solution for the vertical temperature distribution within the semiconfining layer of a typical aquifer system. The solution is an extension of the previous one-dimensional theory by Bredehoeft and Papadopulos [1965]. It provides a quantitative tool for analyzing the uncertainty of the horizontal heat and fluid flow. The analytical results demonstrate that horizontal flow of heat and fluid, if at values much smaller than those of the vertical, has a negligible effect on the vertical temperature distribution but becomes significant when it is comparable to the vertical.

  14. The effect of mechanical activation on the heat capacity of powdered tungsten

    NASA Astrophysics Data System (ADS)

    Malkin, A. I.; Kiselev, M. R.; Klyuev, V. A.; Loznetsova, N. N.; Toporov, Yu. P.

    2012-06-01

    We have studied the heat capacity ( C p ) of a mechanically activated tungsten powder. It is established that the mechanical processing leads to an increase in C p of the metal powder at low temperatures and modifies the character of the temperature dependence of this parameter. The dependences of C p and its heating-induced variation on the treatment duration have been determined. It is concluded that the observed effects are related to the accumulation of defects in the metal grain volume during mechanical activation and their annealing in the course of heating.

  15. Effect of Index of Refraction on Radiation Characteristics in a Heated Absorbing, Emitting, and Scattering Layer

    NASA Technical Reports Server (NTRS)

    Siegel, R.; Spuckler, C. M.

    1992-01-01

    The effect of the index of refraction on the temperature distribution and radiative heat flux in semitransparent materials, such as some ceramics, is investigated analytically. In the case considered here, a plane layer of a ceramic material is subjected to external radiative heating incident on each of its surfaces; the material emits, absorbs, and isotropically scatters radiation. It is shown that, for radiative equilibrium in a gray layer with diffuse interfaces, the temperature distribution and radiative heat flux for any index of refraction can be obtained in a simple manner from the results for an index of refraction of unity.

  16. Developing Evidence to Inform Decisions about Effectiveness (DeCIDE) Network

    Cancer.gov

    The Developing Evidence to Inform Decisions about Effectiveness Network is a network of research centers that the Agency for Healthcare Research and Quality created to conduct practical studies about health care items and services.

  17. Effects of heat and high-pressure treatments on the solubility and immunoreactivity of almond proteins.

    PubMed

    Zhang, Yan; Zhang, Jieqiong; Sheng, Wei; Wang, Shuo; Fu, Tong-Jen

    2016-05-15

    The effects of dry and moist heat, autoclave sterilization and high-pressure treatment on the biochemical characteristics and immunological properties of almond proteins were investigated. Changes in the solubility and immunoreactivity of almond proteins extracted from treated almond flour were evaluated using a total protein assay, indirect competitive inhibition enzyme-linked immunosorbent assay (IC-ELISA), and sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). Almond proteins were stable during dry-heat treatment at temperatures below 250°C. Dry heat at 400°C, boiling, autoclave sterilization and high-pressure treatment in the presence of water at ⩾ 500 MPa greatly reduced the solubility and immunoreactivity of almond proteins. SDS-PAGE revealed that the protein profiles of almond flour samples treated under these conditions also changed significantly. The synergistic effects of heat, pressure and the presence of water contributed to significant changes in solubility and immunoreactivity of almond proteins.

  18. Exercise in the heat: strategies to minimize the adverse effects on performance.

    PubMed

    Terrados, N; Maughan, R J

    1995-01-01

    Exercise in the heat is usually associated with reduced performance; both dehydration and hyperthermia adversely affect mental and physical performance. For athletes from temperate climates, the negative effects of heat had humidity can be attenuated by a period of acclimatization. This requires up to 10-14 days. Endurance-trained individuals already show some of the adaptations that accompany acclimatization, but further adaptation occurs with training in the heat. Prior dehydration has a negative effect even on exercise of short duration where sweat losses are small. The athlete must begin exercise fully hydrated and regular ingestion of fluids is beneficial where the exercise duration exceeds 40 min. Dilute carbohydrate-electrolyte (sodium) drinks are best for fluid replacement and also supply some substrate for the exercising muscles. Post-exercise rehydration requires electrolyte as well as volume replacement. In extreme conditions, neither acclimatization nor fluid replacement will allow hard exercise to be performed without some risk of heat illness.

  19. Effect of Heating Rate on the Refining of Metallurgical-Grade Silicon during Fractional Melting

    NASA Astrophysics Data System (ADS)

    Chung, Juho; Lee, Changbum; Yoon, Wooyoung

    2013-10-01

    Silicon was purified using fractional melting (FM), which is a more effective refining method than fractional solidification. Changes in the silicon microstructure during FM were observed using a scanning electron microscope (SEM) and an electron probe microanalyzer (EPMA). Purity of each sample was investigated using inductively coupled plasma atomic emission spectrometry (ICP-AES) to determine the effects of various heating rates on the efficiency of FM. A refining ratio of 97.28% was the best result that could be obtained for the sample that was heated at a rate of 15 °C/min. For the samples that were heated below 1390 °C lower heating rate resulted in higher refining efficiency. Acid-leaching yielded 99.98% pure silicon samples after FM.

  20. Ordnance gelatin for ballistic studies. Detrimental effect of excess heat used in gelatin preparation.

    PubMed

    Fackler, M L; Malinowski, J A

    1988-09-01

    Most users of ordnance gelatin for ballistics studies are apparently unaware of the detrimental effects on this tissue simulant's properties caused by excess heating in reconstitution of the gelatin powder. Material published by the Gelatin Manufacturers Institute of America states that heating gelatin above 40 degrees C can be detrimental to its properties. The manufacturer of type 250 A Ordnance Gelatin does not include directions for preparation with the gelatin powder. Directions that can be obtained by contacting the manufacturer fail to give any recommendations on the amount of heat applied during gelatin preparation and do not mention the detrimental effects of excess heat. These oversights are corrected in the revised set of directions included in this article. PMID:3177350

  1. Aerodynamic heating on 3-D bodies including the effects of entropy-layer swallowing

    NASA Technical Reports Server (NTRS)

    Dejarnette, F. R.; Hamilton, H. H.

    1974-01-01

    A relatively simple method was developed previously (authors, 1973) for calculating laminar, transitional, and turbulent heating rates on three-dimensional bodies in hypersonic flows. This method was shown to yield reasonably accurate results for laminar heating on blunted circular and elliptical cones and an earlier version of the space shuttle vehicle. As the boundary layer along the surface grows, more and more of the inviscid-flow mass is entrained into the boundary layer, and the streamlines which passed through the nearly normal portion of the bow shock wave are 'swallowed' by the boundary layer. This phenomenon is often referred to as entropy-layer or streamline swallowing, and it can have a significant effect on the calculated heating rates. An approximate, yet simple, method for including the effects of entropy-layer swallowing in the heating-rate calculations is given.

  2. Effect of viscosity and wall heat conduction on shock attenuation in narrow channels

    NASA Astrophysics Data System (ADS)

    Deshpande, A.; Puranik, B.

    2016-07-01

    In the present work, the effects due to viscosity and wall heat conduction on shock propagation and attenuation in narrow channels are numerically investigated. A two-dimensional viscous shock tube configuration is simulated, and heat conduction in the channel walls is explicitly included. The simulation results indicate that the shock attenuation is significantly less in the case of an adiabatic wall, and the use of an isothermal wall model is adequate to take into account the wall heat conduction. A parametric study is performed to characterize the effects of viscous forces and wall heat conduction on shock attenuation, and the behaviour is explained on the basis of boundary layer formation in the post-shock region. A dimensionless parameter that describes the shock attenuation is correlated with the diaphragm pressure ratio and a dimensionless parameter which is expressed using the characteristic Reynolds number and the dimensionless shock travel.

  3. Effects of heat and high-pressure treatments on the solubility and immunoreactivity of almond proteins.

    PubMed

    Zhang, Yan; Zhang, Jieqiong; Sheng, Wei; Wang, Shuo; Fu, Tong-Jen

    2016-05-15

    The effects of dry and moist heat, autoclave sterilization and high-pressure treatment on the biochemical characteristics and immunological properties of almond proteins were investigated. Changes in the solubility and immunoreactivity of almond proteins extracted from treated almond flour were evaluated using a total protein assay, indirect competitive inhibition enzyme-linked immunosorbent assay (IC-ELISA), and sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). Almond proteins were stable during dry-heat treatment at temperatures below 250°C. Dry heat at 400°C, boiling, autoclave sterilization and high-pressure treatment in the presence of water at ⩾ 500 MPa greatly reduced the solubility and immunoreactivity of almond proteins. SDS-PAGE revealed that the protein profiles of almond flour samples treated under these conditions also changed significantly. The synergistic effects of heat, pressure and the presence of water contributed to significant changes in solubility and immunoreactivity of almond proteins. PMID:26776044

  4. Effects of rough boundary on the heat transfer in a thin-film flow

    NASA Astrophysics Data System (ADS)

    Pažanin, Igor; Suárez-Grau, Francisco Javier

    In this Note, a heat flow through a rough thin domain filled with fluid (lubricant) is studied. The domain's thickness is considered as the small parameter ɛ, while the roughness is defined by a periodical function with a period of order ɛ2. We assume that the lubricant is cooled by the exterior medium and we describe the heat exchange on the rough part of the boundary by Newton's cooling law. Depending on the magnitude of the heat transfer coefficient with respect to ɛ, we obtain three different macroscopic models via formal asymptotic analysis. We identify the critical case explicitly acknowledging both roughness-induced effects and the effects of the surrounding medium on heat transfer at main order. We illustrate the obtained results by some numerical simulations.

  5. Heat diode effect and negative differential thermal conductance across nanoscale metal-dielectric interfaces

    NASA Astrophysics Data System (ADS)

    Ren, Jie; Zhu, Jian-Xin

    2013-06-01

    Controlling heat flow by phononic nanodevices has received significant attention recently because of its fundamental and practical implications. Elementary phononic devices such as thermal rectifiers, transistors, and logic gates are essentially based on two intriguing properties: heat diode effect and negative differential thermal conductance. However, little is known about these heat transfer properties across metal-dielectric interfaces, especially at nanoscale. Here we analytically resolve the microscopic mechanism of the nonequilibrium nanoscale energy transfer across metal-dielectric interfaces, where the inelastic electron-phonon scattering directly assists the energy exchange. We demonstrate the emergence of heat diode effect and negative differential thermal conductance in nanoscale interfaces and explain why these novel thermal properties are usually absent in bulk metal-dielectric interfaces. These results will generate exciting prospects for the nanoscale interfacial energy transfer, which should have important implications in designing hybrid circuits for efficient thermal control and open up potential applications in thermal energy harvesting with low-dimensional nanodevices.

  6. Investigation of laser heating effect of metallic nanoparticles on cancer treatment

    NASA Astrophysics Data System (ADS)

    Shan, G. S.; Liu, X. M.; Chen, H. J.; Yu, J. S.; Chen, X. D.; Yao, Y.; Qi, L. M.; Chen, Z. J.

    2016-07-01

    Metallic nanoparticles can be applied for hyperthermia therapy of cancer treatment to enhance the efficacy because of their high absorption rate. The absorption of laser energy by metallic nanoparticles is strongly dependent on the concentration, shape, material of nanoparticles and the wavelength of the laser. However, there is no systematic investigation on the heating effect involving different material, concentration and laser wavelength. In this paper, gold nanoparticles (AuNPs), sliver nanoparticles (AgNPs) and sliver nanowires (AgNWs) with different concentrations are heated by 450nm and 532nm wavelength laser to investigate the heating effect. The result shows that the temperature distribution of heated metallic nanoparticles is non-uniform.

  7. Investigation of arterial gas occlusions. [effect of noncondensable gases on high performance heat pipes

    NASA Technical Reports Server (NTRS)

    Saaski, E. W.

    1974-01-01

    The effect of noncondensable gases on high-performance arterial heat pipes was investigated both analytically and experimentally. Models have been generated which characterize the dissolution of gases in condensate, and the diffusional loss of dissolved gases from condensate in arterial flow. These processes, and others, were used to postulate stability criteria for arterial heat pipes under isothermal and non-isothermal condensate flow conditions. A rigorous second-order gas-loaded heat pipe model, incorporating axial conduction and one-dimensional vapor transport, was produced and used for thermal and gas studies. A Freon-22 (CHCIF2) heat pipe was used with helium and xenon to validate modeling. With helium, experimental data compared well with theory. Unusual gas-control effects with xenon were attributed to high solubility.

  8. Moisture-heat effects on unidirectional composite laminates fracture toughness and fatigue crack growth

    NASA Astrophysics Data System (ADS)

    Zhang, Fusheng; Pzinz, R.; Zichy, J. H.

    1993-04-01

    The heat-moisture effect on interlaminar fracture toughness of T300/914C graphite/epoxy unidirectional composite laminates is investigated under mode I opening loading witb DCB specimen. The fracture toughness in moisture-heat conditioning increases, and the glass transition temperature decreases. SEM fractographs revealed no discernible difference in the fracture surface morphology of moisture-heat and dry conditioned specimens. No fiber bridging occurs in the testing. Delamination fatigue crack growth experiments are carried out on T300/914C graphite/epoxy unidirectional laminates. It is found that the mode I cyclic crack growth rate yields a power low relationship between da/dN and the maximum cyclic strain energy release rate. The crack growth rate of the moisture-heat conditioned specimen is lower than that of the dry conditioned. The environmental effects are explained on the basis of fractography and fracture mechanisms and fracture mechanics.

  9. Anomalous electron heating effects on the E region ionosphere in TIEGCM

    NASA Astrophysics Data System (ADS)

    Liu, Jing; Wang, Wenbin; Oppenheim, Meers; Dimant, Yakov; Wiltberger, Michael; Merkin, Slava

    2016-03-01

    We have recently implemented a new module that includes both the anomalous electron heating and the electron-neutral cooling rate correction associated with the Farley-Buneman Instability (FBI) in the thermosphere-ionosphere electrodynamics global circulation model (TIEGCM). This implementation provides, for the first time, a modeling capability to describe macroscopic effects of the FBI on the ionosphere and thermosphere in the context of a first-principle, self-consistent model. The added heating sources primarily operate between 100 and 130 km altitude, and their magnitudes often exceed auroral precipitation heating in the TIEGCM. The induced changes in E region electron temperature in the auroral oval and polar cap by the FBI are remarkable with a maximum Te approaching 2200 K. This is about 4 times larger than the TIEGCM run without FBI heating. This investigation demonstrates how researchers can add the important effects of the FBI to magnetosphere-ionosphere-thermosphere models and simulators.

  10. Effects of electrode surface roughness on motional heating of trapped ions

    NASA Astrophysics Data System (ADS)

    Lin, Kuan-Yu; Low, Guang Hao; Chuang, Isaac L.

    2016-07-01

    Electric-field noise is a major source of motional heating in trapped-ion quantum computation. While the influence of trap-electrode geometries on electric-field noise has been studied in patch potential and surface adsorbate models, only smooth surfaces are accounted for by current theory. The effects of roughness, a ubiquitous feature of surface electrodes, are poorly understood. We investigate its impact on electric-field noise by deriving a rough-surface Green's function and evaluating its effects on adsorbate-surface binding energies. At cryogenic temperatures, heating-rate contributions from adsorbates are predicted to exhibit an exponential sensitivity to local surface curvature, leading to either a large net enhancement or suppression over smooth surfaces. For typical experimental parameters, orders-of-magnitude variations in total heating rates can occur depending on the spatial distribution of adsorbates. Through careful engineering of electrode surface profiles, our results suggests that heating rates can be tuned over orders of magnitudes.

  11. Side effects of normalising radial basis function networks.

    PubMed

    Shorten, R; Murray-Smith, R

    1996-05-01

    Normalisation of the basis function activations in a Radial Basis Function (RBF) network is a common way of achieving the partition of unity often desired for modelling applications. It results in the basis functions covering the whole of the input space to the same degree. However, normalisation of the basis functions can lead to other effects which are sometimes less desirable for modelling applications. This paper describes some side effects of normalisation which fundamentally alter properties of the basis functions, e.g. the shape is no longer uniform, maxima of basis functions can be shifted from their centres, and the basis functions are no longer guaranteed to decrease monotonically as distance from their centre increases--in many cases basis functions can 'reactivate', i.e. re-appear far from the basis function centre. This paper examines how these phenomena occur, discusses their relevance for non-linear function approximation and examines the effect of normalisation on the network condition number and weights.

  12. Effect of the rate of temperature increase on water quality during heating in electromagnetic- and gas-heated pans.

    PubMed

    Hiratsuka, Hiroshi; Sasaki, Ken

    2004-04-01

    More rapid increases in the pH value and hardness during electromagnetic heating of a pan of water were observed than when the pan was heated by LNG or LPG. The water quality changed universally in several tap water samples across Japan. This quality change was closely correlated with the rate of temperature increase, irrespective of heating by electromagnetic induction, LNG or LPG.

  13. Effect of heat shock on intracellular calcium mobilization in neuroblastoma x glioma hybrid cells.

    PubMed

    Katayama, S; Shuntoh, H; Matsuyama, S; Tanaka, C

    1994-06-01

    The effect of heat shock on agonist-stimulated intracellular Ca2+ mobilization and the expression of heat shock protein 72 (hsp72) in neuroblastoma x glioma hybrid cells (NG 108-15 cells) were examined. Hsp72 was expressed at 6 h after heat shock (42.5 degrees C, 2 h), reached a maximum at 12 h, and decreased thereafter. Bradykinin-induced [Ca2+]i rise was attenuated to 28% of control by heat shock at 2 h after heat shock, and reversion to the control level was seen 12 h later. When the cells were treated with quercetin or antisense oligodeoxyribonucleotide against hsp72 cDNA, the synthesis of hsp72 was not induced by heat shock, whereas bradykinin-induced [Ca2+]i rise was abolished and the [Ca2+]i rise was not restored. Recovery from this stressed condition was evident when cells were stimulated by the Ca(2+)-ATPase inhibitor thapsigargin, even in the presence of either quercetin or antisense oligodeoxyribonucleotide. Inositol 1,4,5-trisphosphate (IP3) production was not altered by heat shock at 12 h after heat shock, whereas IP3 receptor binding activity was reduced to 45.3%. In the presence of quercetin or antisense oligodeoxyribonucleotide, IP3 receptor binding activity decreased and reached 27.2% of the control 12 h after heat shock. Our working thesis is that heat shock transiently suppresses the IP3-mediated intracellular Ca2+ signal transduction system and that hsp72 is involved in the recovery of bradykinin-induced [Ca2+]i rise.

  14. Effect of heat treatment on the antioxidant activity of extracts from citrus peels.

    PubMed

    Jeong, Seok-Moon; Kim, So-Young; Kim, Dong-Ryul; Jo, Seong-Chun; Nam, K C; Ahn, D U; Lee, Seung-Cheol

    2004-06-01

    The effect of heat treatment on the antioxidant activity of extracts from Citrus unshiu peels was evaluated. Citrus peels (CP) (5 g) were placed in Pyrex Petri dishes (8.0 cm diameter) and heat-treated at 50, 100, or 150 degrees C for 10, 20, 30, 40, 50, and 60 min in an electric muffle furnace. After heat treatment, 70% ethanol extract (EE) and water extract (WE) (0.1 g/10 mL) of CP were prepared, and total phenol contents (TPC), radical scavenging activity (RSA), and reducing power of the extracts were determined. The antioxidant activities of CP extracts increased as heating temperature increased. For example, heat treatment of CP at 150 degrees C for 60 min increased the TPC, RSA, and reducing power of EE from 71.8 to 171.0 microM, from 29.64 to 64.25%, and from 0.45 to 0.82, respectively, compared to non-heat-treated control. In the case of WE from CP heat-treated at the same conditions (150 degrees C for 60 min), the TPC, RSA, and reducing power also increased from 84.4 to 204.9 microM, from 15.81 to 58.26%, and from 0.27 to 0.96, respectively. Several low molecular weight phenolic compounds such as 2,3-diacetyl-1-phenylnaphthalene, ferulic acid, p-hydroxybenzaldoxime, 5-hydroxyvaleric acid, 2,3-diacetyl-1-phenylnaphthalene, and vanillic acid were newly formed in the CP heated at 150 degrees C for 30 min. These results indicated that the antioxidant activity of CP extracts was significantly affected by heating temperature and duration of treatment on CP and that the heating process can be used as a tool for increasing the antioxidant activity of CP. PMID:15161203

  15. Nonlinear Effects in Single-Pass ICRF Heating

    NASA Technical Reports Server (NTRS)

    Arefiev, A. V.; Breizman, B. N.

    1999-01-01

    The Variable Specific Impulse Magnetoplasma Rocket (VASIMR) concept employs Ion Cyclotron Resonant Frequency (ICRF) heating as the main power deposition mechanism. Since the ions accelerate to the full energy in a single pass through the cyclotron resonance, their response to the RF-field will be essentially nonlinear - hence the motivation to amend the commonly used linear approach to the problem. In a collisionless plasma, the energy gain of an accelerated ion is limited by the time the particle spends at the resonance. This time is affected by: (1) incident flow velocity, (2) longitudinal grad B force, (3) ambipolar electric field, and (4) ponderomotive force of the RF-field. Our analysis shows that the grad B force is the dominant factor at low to moderate levels of RF-power. We present nonlinear scaling for the energy gain and the absorption efficiency with RF-power and plasma parameters. We also demonstrate that the nonlinear regime exhibits a steep decrease in the plasma density at the resonance.

  16. Register Closing Effects on Forced Air Heating System Performance

    SciTech Connect

    Walker, Iain S.

    2003-11-01

    Closing registers in forced air heating systems and leaving some rooms in a house unconditioned has been suggested as a method of quickly saving energy for California consumers. This study combined laboratory measurements of the changes in duct leakage as registers are closed together with modeling techniques to estimate the changes in energy use attributed to closing registers. The results of this study showed that register closing led to increased energy use for a typical California house over a wide combination of climate, duct leakage and number of closed registers. The reduction in building thermal loads due to conditioning only a part of the house was offset by increased duct system losses; mostly due to increased duct leakage. Therefore, the register closing technique is not recommended as a viable energy saving strategy for California houses with ducts located outside conditioned space. The energy penalty associated with the register closing technique was found to be minimized if registers furthest from the air handler are closed first because this tends to only affect the pressures and air leakage for the closed off branch. Closing registers nearer the air handler tends to increase the pressures and air leakage for the whole system. Closing too many registers (more than 60%) is not recommended because the added flow resistance severely restricts the air flow though the system leading to safety concerns. For example, furnaces may operate on the high-limit switch and cooling systems may suffer from frozen coils.

  17. Effect of Channel Configurations for Tritium Transfer in Printed Circuit Heat Exchangers

    SciTech Connect

    Chang Oh; Eung Kim; Robert Shrake; Mike Patterson

    2009-05-01

    The Next Generation Nuclear Plant (NGNP), a very High temperature Gas-Cooled Reactor (VHTR) concept, will provide the first demonstration of a closed-loop Brayton cycle at a commercial scale of a few hundred megawatts electric and hydrogen production. The power conversion system (PCS) for the NGNP will take advantage of the significantly higher reactor outlet temperatures of the VHTR to provide higher efficiencies than can be achieved in the current generation of light water reactors. Besides demonstrating a system design that can be used directly for subsequent commercial deployment, the NGNP will demonstrate key technology elements that can be used in subsequent advanced power conversion systems for other Generation IV reactors. In anticipation of the design, development and procurement of an advanced power conversion system for the NGNP, the system integration of the NGNP and hydrogen plant was initiated to identify the important design and technology options that must be considered in evaluating the performance of the proposed NGNP. In the VHTR system, an intermediate heat exchanger (IHX), which transfers heat from the reactor core to the electricity or hydrogen production system is one key component, and its effectiveness is directly related to the system overall efficiency. In the VHTRs, the gas fluids used for coolant generally have poor heat transfer capability, so it requires very large surface area for a given condition. For this reason, a compact heat exchanger (CHE), which is widely used in industry especially for gasto-gas or gas-to-liquid heat exchange is considered as a potential candidate for an IHX replacing the classical shell and tube type heat exchanger. A compact heat exchanger is arbitrary referred to be a heat exchanger having a surface area density greater than 700 m2/m3. The compactness is usually achieved by fins and micro-channels, and leads to the enormous heat transfer enhancement and size reduction. The surface area density is the

  18. Network-level fallout radiation-effects assessment. Final report

    SciTech Connect

    Not Available

    1989-05-12

    The EMP Mitigation Program analyzes, and where feasible, lessens the degradation effects of EMP on national telecommunication resources. The program focuses on the resources of the public switched network (PSN) because the PSN comprises the largest, most diverse set of telecommunication assets in the United States and is the focus of National Security Emergency Preparedness (NSEP) telecommunication enhancement activities. Additionally, the majority of various organizations rely on the PSN to conduct their NSEP telecommunications responsibilities. Telecommunication equipment is most susceptible to high altitude EMP (HEMP) which occurs when a nuclear weapon is detonated at an altitude greater that 50 km above the earth's surface. In addition to studying the effects of EMP, the program has expanded to address the effects of fallout radiation and serve traffic congestion on the PSN.

  19. Joule heating effects on MHD mixed convection of a Jeffrey fluid over a stretching sheet with power law heat flux: A numerical study

    NASA Astrophysics Data System (ADS)

    Babu, D. Harish; Narayana, P. V. Satya

    2016-08-01

    An analysis has been carried out to study the Joule heating effect on MHD heat transfer of an incompressible Jeffrey fluid due to a stretching porous sheet with power law heat flux and heat source. A constant magnetic field is applied normal to the stretching surface. The basic governing equations are reduced into the coupled nonlinear ordinary differential equations by using similarity transformations. The resulting equations are then solved numerically by shooting method with fourth order Runge-Kutta scheme. The effects of various physical parameters entering into the problem on dimensionless velocity and temperature distribution are discussed through graphs and tables. The results reveal that the momentum and thermal boundary layer thickness are significantly influenced by Deborah number (β), ratio of relaxation and retardation times parameter (λ), heat generation parameter (β*), Eckert number (Ec) and magnetic field parameter (M). A comparison with the previously published works shows excellent agreement.

  20. Joule-Thomson effect and internal convection heat transfer in turbulent He II flow

    NASA Technical Reports Server (NTRS)

    Walstrom, P. L.

    1988-01-01

    The temperature rise in highly turbulent He II flowing in tubing was measured in the temperature range 1.6-2.1 K. The effect of internal convection heat transport on the predicted temperature profiles is calculated from the two-fluid model with mutual friction. The model predictions are in good agreement with the measurements, provided that the pressure gradient term is retained in the expression for internal convection heat flow.