Family finances in the U.S.: recent evidence from the Survey of Consumer Finances

Using data that have just become available from the 1995 Survey of Consumer Finances along with data from the 1989 and 1992 versions of the survey, this article provides a detailed picture of recent changes in the income, net worth, assets, and liabilities of U.S. families. It also presents information on families' saving, unrealized capital gains, debt payments, and institutional providers of credit. Of the developments the article reports, a few are particularly noteworthy. First, between the 1992 and 1995 surveys, both median family income and median family net worth rose in constant dollars. The former, however, remained below the level measured in 1989, whereas the latter returned to the 1989 level. Second, the percentage of families who owned publicly traded stock and the amount of their holdings expanded greatly over the six-year period. Finally, there was little evidence of a serious rise in debt payment problems between 1992 and 1995, even though both the share of families with debt and the median amount of their debt rose.Consumer behavior ; Saving and investment

On analysis of chemical reactions coupled gas flows in SOFCs

This paper was presented at the 2nd Micro and Nano Flows Conference (MNF2009), which was held at Brunel University, West London, UK. The conference was organised by Brunel University and supported by the Institution of Mechanical Engineers, IPEM, the Italian Union of Thermofluid dynamics, the Process Intensification Network, HEXAG - the Heat Exchange Action Group and the Institute of Mathematics and its Applications.Solid oxide fuel cell (SOFC) is among others one of the most promising technologies for electricity energy generation. A recent new trends is to reduce its operating temperature from 1000oC to 800oC by employing a thick porous layer as the supporting structure. Various transport processes occurred are strongly affected by catalytic chemical/electrochemical reactions appearing in nano- or/and microstructured and multi-functional porous electrodes. It is particularly true if methane is used as the fuel, and internal reforming reactions within the microstructured porous anodes enable the conversion of the methane into H2 and CO. To deeply understand the chemical reaction coupled gas flow and heat transfer in the microstructured porous anode, a fully three-dimensional numerical calculation procedure (CFD) is developed and applied. The species mass/heat generation and consumption related to the internal reforming reactions and the electrochemical reaction have been identified and employed in the study. The variable thermalphysical properties and transport parameters of the fuel gas mixture have also been taken into account. Furthermore, the heat transfer due to the fuel gas flow is implemented into the energy balance based on multi-component diffusion models. Finally, various issues connecting to the micro models of the surface reactions are discussed and reviewed.Thi study is supported by the Swedish Research Council (VR) and the National Natural Science Foundation of China (NSFC-50706004)

Effect of surfactant on flow boiling heat transfer of ethylene glycol/water mixtures in a mini-tube

This paper was presented at the 4th Micro and Nano Flows Conference (MNF2014), which was held at University College, London, UK. The conference was organised by Brunel University and supported by the Italian Union of Thermofluiddynamics, IPEM, the Process Intensification Network, the Institution of Mechanical Engineers, the Heat Transfer Society, HEXAG - the Heat Exchange Action Group, and the Energy Institute, ASME Press, LCN London Centre for Nanotechnology, UCL University College London, UCL Engineering, the International NanoScience Community, www.nanopaprika.eu.In this study, the effect of adding a surfactant (sodium dodeobcylbenzene sulfonate, SDBS) to ethylene glycol/water mixtures boiling in a vertical mini-tube was studied. Experiments were done using solutions containing 300 ppm by weight of surfactant and the results were compared with those for pure mixture. Local heat transfer coefficient was measured and found to be dependent on the mass quality. Addition of surfactant significantly enhanced the evaporation of saturated liquid, so that the difference between outlet fluid temperature and outlet bubble point temperature of SDBS solutions was much higher than that of ethylene glycol/water mixture. Though the surfactant intensifies the vaporization process, it does not necessarily enhance the heat transfer coefficient. The heat transfer coefficients at two different mass fluxes were compared, and the result could be explained based on the local flow pattern and heat transfer mechanism. After a critical quality, higher quality will deteriorate the heat transfer due to intermittent dryout, therefore adding surfactant to generate more vapor may have a negative effect on the heat transfer of flow boiling in a mini-tube, which is contrast to the experience of enhancing nucleate pool boiling heat transfer with trace surfactant

Thermal conductivity and rheology behavior of aqueous nanofluids containing alumina and carbon nanotubes

This paper was presented at the 4th Micro and Nano Flows Conference (MNF2014), which was held at University College, London, UK. The conference was organised by Brunel University and supported by the Italian Union of Thermofluiddynamics, IPEM, the Process Intensification Network, the Institution of Mechanical Engineers, the Heat Transfer Society, HEXAG - the Heat Exchange Action Group, and the Energy Institute, ASME Press, LCN London Centre for Nanotechnology, UCL University College London, UCL Engineering, the International NanoScience Community, www.nanopaprika.eu.In this study, thermal conductivity and rheology behavior of aqueous alumina and multi-walled carbon nanotube (MWCNT) nanofluids were measured and compared with several analytical models. Both thermal conductivity and viscosity of the two nanofluids increase with increasing volume fraction. The experimental thermal conductivity data for the two nanofluids are located near the lower Hashin-Shtrikman bound and far away from the upper Hashin-Shtrikman bound. Therefore there is still enough room for thermal conductivity enhancement. Further conductivity enhancement of the nanofluids can be achieved by manipulating particle or agglomeration distribution and morphology. The structure-property relationship was checked for the nanofluids. Possible agglomeration size and interfacial thermal resistance were obtained and partially validated. Based on the Chen et al. model, a revised model was developed by incorporating the effects of interfacial thermal resistance into the Hamilton-Crosser model. The revised model can accurately reproduce the experimental data based on the agglomeration size extracted from the rheology analysis. In addition, thermal conductivity change of the alumina/water nanofluid with elapsed time was also investigated. The average thermal conductivity decreases with elapsed time. Besides, thermal conductivity measurements were conducted for nanofluid mixtures of alumina/water and MWCNT/water nanofluids

Progress in phase change nano-emulsions for energy applications-A concise review

Thermal energy storage and transport are central to the wide application of renewable energy. With excellent storage capacities, latent heat storage is more promising than sensible one. Phase change materials are the primary storage materials for latent heat storage. Phase change nanoemulsions are developed for latent heat storage in flow systems that can be used as heat transport and thermal storage purposes, offering improved heat transfer, pumping power, and higher storage capacities. This review is focused on the new advances in phase change nanoemulsions for energy applications. The phase change nanoemulsions are introduced and their features and classification are provided. The preparation methods and thermophysical properties of these nanostructured phase changeable fluids are discussed and, material synthesis and property characterization are covered. Finally, the applications of this class of fluids in different energy systems are reviewed. The major barriers to the applications of phase change nanoemulsions, including instability and high degree of super-cooling, are discussed

Numerical investigation of an oscillating gas bubble in an ultrasonic field

Paper presented to the 10th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Florida, 14-16 July 2014.The discovery of acoustic cavitation phenomenon is an important role in the design of a wide range of devices handling liquids and it has led to a renewed interest in the bubble dynamics in a sound field. In this study, the nonlinear behaviour of individual gas bubble in liquid under the action of ultrasound fields has been analysed, and simulated results of formation and collapse of a bubble have been provided. The characterization of acoustic cavitation bubbles under the influence of periodic pressure field, e.g., the motion of the bubble surface, pressure, temperature and density fields inside the bubble have been investigated and the results are compared with experimental data. The numerically calculated results reveal that the assumption of polytropic approximation inside the bubble predicts that a radius-time curve does not fit to the observed data. Also, the results indicate that the pressure gradient and the heat transfer inside the bubble and across the bubble surface play a major role to predict the extreme conditions associated with the bubble collapse.dc201

IMECE2006-13668 NUMERICAL SIMULATIONS OF UNSTEADY FLUID FLOW AND HEAT TRANSFER IN A TRANSONIC TURBINE STAGE

ABSTRACT In this work, a numerical study has been performed to simulate the unsteady fluid flow and heat transfer in a transonic highpressure turbine stage. The main objective of this study is to understand the unsteady flow field and heat transfer in a single transonic turbine stage using an unsteady structured NavierStokes solver. For the time accurate computation, a fully implicit time discretization, dual-time stepping, is performed. The results of the CFD simulations are compared with experimental heat transfer and aerodynamic results available for the so-called MT1 turbine stage. The predicted heat transfer and static pressure distributions show reasonable agreement with experimental data. In particular, the results show significant fluctuations in heat transfer and pressure at midspan on the rotor blade, and that the rotor has a limited influence on the heat transfer to the NGV at mid span. INTRODUCTION The flow field in a high pressure gas turbine is very complex. It is strongly three-dimensional, unsteady, viscous, with several types of secondary flows and vortices (passage vortex, leakage flow, horseshoe vortex, etc.). Transitional flow and high turbulence intensity result in additional complexities. The most significant contribution to the unsteadiness of the flow field is the relative motion of the blade rows. The understanding of such complex flow fields and the heat transfer characteristics is necessary to improve the blade design and prediction in terms of efficiency as well as the evaluation of mechanical and thermal fatigue. In the past decade computational fluid dynamics (CFD) have started to play an increasingly important role in the study of turbine blade for both flow and heat transfer. The advantage of using CFD for turbine heat transfer predictions is that the heat transfer in regions of complex flow fields (secondary flows, leakage flow, rotation, film cooling, stagnation point, etc.) can be reasonabl

Project Coolbit: Can your watch predict heat stress and thermal comfort sensation?

10.1088/1748-9326/abd130ENVIRONMENTAL RESEARCH LETTERS16

High-mobility group box-1 protein, lipopolysaccharide-binding protein, interleukin-6 and C-reactive protein in children with community acquired infections and bacteraemia: a prospective study

<p>Abstract</p> <p>Introduction</p> <p>Even though sepsis is one of the common causes of children morbidity and mortality, specific inflammatory markers for identifying sepsis are less studied in children. The main aim of this study was to compare the levels of high-mobility group box-1 protein (HMGB1), Lipopolysaccharide-binding protein (LBP), Interleukin-6 (IL-6) and C-reactive protein (CRP) between infected children without systemic inflammatory response syndrome (SIRS) and children with severe and less severe sepsis. The second aim was to examine HMGB1, LBP, IL6 and CRP as markers for of bacteraemia.</p> <p>Methods</p> <p>Totally, 140 children with suspected or proven infections admitted to the Children's Clinical University Hospital of Latvia during 2008 and 2009 were included. Clinical and demographical information as well as infection focus were assessed in all patients. HMGB1, LBP, IL-6 and CRP blood samples were determined. Children with suspected or diagnosed infections were categorized into three groups of severity of infection: (i) infected without SIRS (n = 36), (ii) sepsis (n = 91) and, (iii) severe sepsis (n = 13). They were furthermore classified according bacteraemia into (i) bacteremia (n = 30) and (ii) no bacteraemia (n = 74).</p> <p>Results</p> <p>There was no statistically significant difference in HMGB1 levels between children with different levels of sepsis or with and without bacteraemia. The levels of LBP, IL-6 and CRP were statistically significantly higher among patients with sepsis compared to those infected but without SIRS (<it>p </it>< 0.001). Furthermore, LBP, IL-6 and CRP were significantly higher in children with severe sepsis compared to those ones with less severe sepsis (<it>p </it>< 0.001). Median values of LBP, IL6 and CRP were significantly higher in children with bacteraemia compared to those without bacteraemia. The area under the receiver operating curve (ROC) for detecting bacteraemia was 0.87 for both IL6 and CRP and 0.82 for LBP, respectively.</p> <p>Conclusion</p> <p>Elevated levels of LBP, IL-6 and CRP were associated with a more severe level of infection in children. Whereas LBP, IL-6 and CRP seem to be good markers to detect patients with bacteraemia, HMGB1 seem to be of minor importance. LBP, IL-6 and CRP levels may serve as good biomarkers for identifying children with severe sepsis and bacteraemia and, thus, may be routinely used in clinical practice.</p