Effect of Phase Change Materials (PCMs Integrated into a Concrete Block on Heat Gain Prevention in a Hot Climate

Directory of Open Access Journals (Sweden)

Ahmad Hasan

2016-10-01

Full Text Available In the current study, a phase change material (PCM contained in an insulated concrete block is tested in extremely hot weather in the United Arab Emirates (UAE to evaluate its cooling performance. An insulated chamber is constructed behind the block containing PCM to mimic a scaled down indoor space. The effect of placement of the PCM layer on heat gain indoors is studied at two locations: adjacent to the outer as well as the inner concrete layer. The inclusion of PCM reduced heat gain through concrete blocks compared to blocks without PCM, yielding a drop in cooling load indoors. The placement of PCM and insulation layers adjacent to indoors exhibited better cooling performance compared to that adjacent to the outdoors. In the best case, a temperature drop of 8.5% and a time lag of 2.6 h are achieved in peak indoor temperature, rendering a reduction of 44% in the heat gain. In the tested hot climate, the higher ambient temperature and the lower wind speed hampered heat dissipation and PCM re-solidification by natural ventilation. The findings recommend employing a mechanical ventilation in hot climates to enhance regeneration of the PCM to solid state for its optimal performance.

Experience gained in France on heat recovery from nuclear plants for agriculture and pisciculture

International Nuclear Information System (INIS)

Balligand, P.; Le Gouellec, P.; Dumont, M.; Grauby, A.

1978-01-01

Since 1972, the Commissariat a l'Energie Atomique, Electricite de France, and the French Ministry of Agriculture have jointly examined the possibility of using thermal wastes from nuclear power plants for the benefit of agricultural production. A new process to heat greenhouses with water at 303 K using a double-wall plastic mulching laid directly on the soil has been successfully used for a few years on several hectares. When necessary, heat pumps are utilized. Very good results have been obtained for tomatoes, cucumbers, flowers, and strawberries, etc. Outdoor soil heating with buried pipes has been tested in Cadarache near an experimental pressurized water reactor for market garden crops and forestry. Gains in precocity and yield have been excellent, especially for asparagus, strawberries, and potatoes. Growing of eels has been four times faster in warm water over one year

Light-scattering properties of a woven shade-screen material used for daylighting and solar heat-gain control

Energy Technology Data Exchange (ETDEWEB)

Jonsson, Jacob; Jonsson, Jacob C.; Lee, Eleanor S.; Rubin, Mike

2008-08-01

Shade-screens are widely used in commercial buildings as a way to limit the amount of direct sunlight that can disturb people in the building. The shade screens also reduce the solar heat-gain through glazing the system. Modern energy and daylighting analysis software such as EnergyPlus and Radiance require complete scattering properties of the scattering materials in the system. In this paper a shade screen used in the LBNL daylighting testbed is characterized using a photogoniometer and a normal angle of incidence integrating sphere. The data is used to create a complete bi-directional scattering distribution function (BSDF) that can be used in simulation programs. The resulting BSDF is compared to a model BADFs, both directly and by calculating the solar heat-gain coefficient for a dual pane system using Window 6.

Energy Gaining Windows for Residental Buildings

DEFF Research Database (Denmark)

Kragh, Jesper; Laustsen, Jacob Birck; Svendsen, Svend

2008-01-01

window is made of fiber-reinforced plastic (plastic reinforced by fine fibers made of glass). This composite material is a weatherproof material with very low thermal conductivity and high mechanical strength. These properties make the material very suitable for frame profiles due to lower heat loss...... minus the heat loss integrated over the heating season. It is assumed that in northern cold climates all of the solar gain during the heating season can be utilized for space heating. Problems with overheating in the summer period must be solved with overhang or moveable solar shading devices. Two...... and longer durability of the window. The glazing in these fiber reinforced polyester windows is both unsealed and sealed triple glazing units. To increase the net energy gain slim frame profiles have been developed to increase the glazing area and thereby the solar gain. The challenge when developing slim...

An inverse method for calculation of thermal inertia and heat gain in air conditioning and refrigeration systems

International Nuclear Information System (INIS)

Fayazbakhsh, M.A.; Bagheri, F.; Bahrami, M.

2015-01-01

Highlights: • An inverse method is proposed to calculate thermal inertia in HVAC-R systems. • Real-time thermal loads are estimated using the proposed intelligent algorithm. • Calculation algorithm is validated with on-site measurements. • Freezer duty cycle data are extracted only based on temperature measurements. - Abstract: A new inverse method is proposed for estimation of thermal inertia and heat gain in air conditioning and refrigeration systems using on-site temperature measurements. The method is applied on a walk-in freezer room of a restaurant in Surrey, British Columbia, Canada during one week of its regular operation. The thermal inertia and instantaneous heat gain are calculated and the results are validated using actual information of the materials inside the freezer room. The proposed method can be implemented in intelligent control systems designed for new and existing HVAC-R systems to improve their overall energy efficiency and reduce their environmental impacts

The contact heat conductance at diamond-OFHC copper interface with GaIn eutectic as a heat transfer medium

International Nuclear Information System (INIS)

Assoufid, L.; Khounsary, A.M.

1996-01-01

Results of an experimental study of the contact heat conductance across a single diamond crystal interface with OFHC copper (Cu) are reported. Gallium-indium (GaIn) eutectic was used as an interstitial material. Contact conductance data are important in the design and the prediction of the performance of x-ray diamond monochromators under high-heat-load conditions. Two sets of experiments were carried out. In one, the copper surface in contact with diamond was polished and then electroless plated with 1 μm of nickel, while in the other, the copper contact surface was left as machined. Measured average interface heat conductances are 44.7 ±8 W/cm 2 -K for nonplated copper and 23.0 ±3 W/cm 2 -K for nickel-plated copper. For reference, the thermal contact conductances at a copper-copper interface (without diamond) were also measured, and the results are reported. A typical diamond monochromator, 0.2 mm thick, will absorb about 44 W under a standard undulator beam at the Advanced Photon Source. The measured conductance for nickel-plated copper suggests that the temperature drop across the interface of diamond and nickel-plated copper, with a 20 mm 2 contact area, will be about 10 degree C. Therefore temperature rises are rather modest, and the accuracy of the measured contact conductances presented here are sufficient for design purposes

Western Canadian Sedimentary Basin temperature–depth transients from repeated well logs: evidence of recent decade subsurface heat gain due to climatic warming

Czech Academy of Sciences Publication Activity Database

Majorowicz, J.; Skinner, W.; Šafanda, Jan

2012-01-01

Roč. 9, č. 2 (2012), s. 127-137 ISSN 1742-2132 Institutional research plan: CEZ:AV0Z30120515 Keywords : borehole temperatures * climate warming * ground heat flux and heat gain * Canadian Prairies Subject RIV: DC - Siesmology, Volcanology, Earth Structure Impact factor: 0.721, year: 2012

Solar Energy Gain and Space-Heating Energy Supply Analyses for Solid-Wall Dwelling Retrofitted with the Experimentally Achievable U-value of Novel Triple Vacuum Glazing

Directory of Open Access Journals (Sweden)

Saim Memon

2017-06-01

Full Text Available A considerable effort is devoted to devising retrofit solutions for reducing space-heating energy in the domestic sector. Existing UK solid-wall dwellings, which have both heritage values and historic fabric, are being improved but they tend to have meagre thermal performance, partly, due to the heat-loss through glazings. This paper takes comparative analyses approach to envisage space-heating supply required in order to maintain thermal comfort temperatures and attainable solar energy gains to households with the retrofit of an experimentally achievable thermal performance of the fabricated sample of triple vacuum glazing to a UK solid-wall dwelling. 3D dynamic thermal models (timely regimes of heating, occupancy, ventilation and internal heat gains of an externally-insulated solid-wall detached dwelling with a range of existing glazing types along with triple vacuum glazings are modelled. A dramatic decrease of space-heating load and moderate increase of solar gains are resulted with the dwelling of newly achievable triple vacuum glazings (having centre-of-pane U-value of 0.33 Wm-2K-1 compared to conventional glazing types. The space-heating annual cost of single glazed dwellings was minimised to 15.31% (≈USD 90.7 with the retrofit of triple-vacuum glazings. An influence of total heat-loss through the fabric of solid-wall dwelling was analysed with steady-state calculations which indicates a fall of 10.23 % with triple vacuum glazings compared to single glazings.

Experience gained in the process of the variable mass heat flow control implemented in the district heat supply system of the city of Gyor

Energy Technology Data Exchange (ETDEWEB)

Nagy, F.; Milanovich, L.; Lelek, J.; Kekk, I. [District Heating LTD. of Gyor (Hungary)

1996-11-01

The district heating system of the city of Gyor is fed from a hot water boiler plant. The total heat demand for 23,000 residential homes and several public facilities is 260 MW. The variable mass flow control was implemented in 1991 through 1992. Design, preparatory job and the majority of implementation was carried out without external involvement. The paper presents historical background and brief project presentation which is followed by comparative presentation of the variable mass flow control and constant mass flow control. This comparative survey has been conducted on the basis of operating data for 1993 and those for 1988. In the conclusion the gained experience is summarized.

Estimation of combustion flue gas acid dew point during heat recovery and efficiency gain

Energy Technology Data Exchange (ETDEWEB)

Bahadori, A. [Curtin University of Technology, Perth, WA (Australia)

2011-06-15

When cooling combustion flue gas for heat recovery and efficiency gain, the temperature must not be allowed to drop below the sulfur trioxide dew point. Below the SO{sub 3} dew point, very corrosive sulfuric acid forms and leads to operational hazards on metal surfaces. In the present work, simple-to-use predictive tool, which is easier than existing approaches, less complicated with fewer computations is formulated to arrive at an appropriate estimation of acid dew point during combustion flue gas cooling which depends on fuel type, sulfur content in fuel, and excess air levels. The resulting information can then be applied to estimate the acid dew point, for sulfur in various fuels up to 0.10 volume fraction in gas (0.10 mass fraction in liquid), excess air fractions up to 0.25, and elemental concentrations of carbon up to 3. The proposed predictive tool shows a very good agreement with the reported data wherein the average absolute deviation percent was found to be around 3.18%. This approach can be of immense practical value for engineers and scientists for a quick estimation of acid dew point during combustion flue gas cooling for heat recovery and efficiency gain for wide range of operating conditions without the necessity of any pilot plant setup and tedious experimental trials. In particular, process and combustion engineers would find the tool to be user friendly involving transparent calculations with no complex expressions for their applications.

Ground surface temperature and continental heat gain: uncertainties from underground

International Nuclear Information System (INIS)

Beltrami, Hugo; Matharoo, Gurpreet S; Smerdon, Jason E

2015-01-01

Temperature changes at the Earth's surface propagate and are recorded underground as perturbations to the equilibrium thermal regime associated with the heat flow from the Earth's interior. Borehole climatology is concerned with the analysis and interpretation of these downward propagating subsurface temperature anomalies in terms of surface climate. Proper determination of the steady-state geothermal regime is therefore crucial because it is the reference against which climate-induced subsurface temperature anomalies are estimated. Here, we examine the effects of data noise on the determination of the steady-state geothermal regime of the subsurface and the subsequent impact on estimates of ground surface temperature (GST) history and heat gain. We carry out a series of Monte Carlo experiments using 1000 Gaussian noise realizations and depth sections of 100 and 200 m as for steady-state estimates depth intervals, as well as a range of data sampling intervals from 10 m to 0.02 m. Results indicate that typical uncertainties for 50 year averages are on the order of ±0.02 K for the most recent 100 year period. These uncertainties grow with decreasing sampling intervals, reaching about ±0.1 K for a 10 m sampling interval under identical conditions and target period. Uncertainties increase for progressively older periods, reaching ±0.3 K at 500 years before present for a 10 m sampling interval. The uncertainties in reconstructed GST histories for the Northern Hemisphere for the most recent 50 year period can reach a maximum of ±0.5 K in some areas. We suggest that continuous logging should be the preferred approach when measuring geothermal data for climate reconstructions, and that for those using the International Heat Flow Commission database for borehole climatology, the steady-state thermal conditions should be estimated from boreholes as deep as possible and using a large fitting depth range (∼100 m). (letter)

The effect and contribution of wind generated rotation on outlet temperature and heat gain of LS-2 parabolic trough solar collector

Directory of Open Access Journals (Sweden)

Sadaghiyani Omid Karimi

2013-01-01

Full Text Available The Monte Carlo ray tracing method is applied and coupled with finite volume numerical methods to study effect of rotation on outlet temperature and heat gain of LS-2 parabolic trough concentrator (PTC. Based on effect of sunshape, curve of mirror and use of MCRT, heat flux distribution around of inner wall of evacuated tube is calculated. After calculation of heat flux, the geometry of LS-2 Luz collector is created and finite volume method is applied to simulate. The obtained results are compared with Dudley et al test results for irrotational cases to validate these numerical solving models. Consider that, for rotational models ,the solving method separately with K.S. Ball's results. In this work, according to the structure of mentioned collector, we use plug as a flow restriction. In the rotational case studies, the inner wall rotates with different angular speeds. We compare results of rotational collector with irrotational. Also for these two main states, the location of plug changed then outlet temperature and heat gain of collector are studied. The results show that rotation have positive role on heat transfer processing and the rotational plug in bottom half of tube have better effectual than upper half of tube. Also the contribution of rotation is calculated in the all of case studies. Working fluid of these study is one of the oil derivatives namely Syltherm-800. The power of wind can be used to rotate tube of collector.

Solar Heat Gain Reduction of Ventilated Double Skin Windows without a Shading Device

Directory of Open Access Journals (Sweden)

Bokyoung Koo

2017-12-01

Full Text Available With global efforts to strengthen various energy-saving policies for buildings to reduce greenhouse gas emissions, in South Korea, new laws and regulations have been in force since May 2015 to install shading devices in public buildings and to include the solar heat gain coefficient (SHGC reduction performance of shading devices in the evaluation of building performance. By making a ventilated air layer outer glass and inner glass to lower the temperatures of the air layer and glass surface, it is possible to reduce the amount of heat flowing into the building while maintaining the same level of light transmission as plain window systems. This study proposes a double-skin façade window with a 20 mm ventilated air cavity, and assumes that insolation inflow indoors would be reduced through ventilation in the air cavity. The artificial solar lab test results show that the SHGC can be lowered through ventilation by 28% to 52.9%. Additionally, in an outdoor test cell experiment, the results show that the mean temperature was 0.6 K and the peak temperature was 0.9 K lower with ventilation in the air cavity than that without ventilation in the air cavity.

Review: heat pipe heat exchangers at IROST

OpenAIRE

E. Azad

2012-01-01

The use of the heat pipe as a component in a heat recovery device has gained worldwide acceptance. Heat pipes are passive, highly reliable and offer high heat transfer rates. This study summarizes the investigation of different types of heat pipe heat recovery systems (HPHRSs). The studies are classified on the basis of the type of the HPHRS. This research is based on 30 years of experience on heat pipe and heat recovery systems that are presented in this study. Copyright , Oxford University ...

Energy performance of windows based on the net energy gain

DEFF Research Database (Denmark)

Svendsen, Svend; Kragh, Jesper; Laustsen, Jacob Birck

2005-01-01

The paper presents a new method to set up energy performance requirements and energy classes for windows of all dimensions and configurations. The net energy gain of windows is the solar gain minus the heat loss integrated over the heating season. The net energy gain can be calculated for one...... be expressed as a function of two parameters representing the energy performance and two parameters representing the geometry of the window. The two energy performance parameters are the net energy gain per area of the glazing unit and the sum of the heat losses through the frame and the assembly per length...... of the frame. The two geometry numbers are the area of the glazing unit relative to the window area and the length of the frame profiles relative to the window area. Requirements and classes for the energy performance of the window can be given by assigning values to the two energy performance parameters...

Geothermal heat pumps - gaining ground in the UK and worldwide

International Nuclear Information System (INIS)

Curtis, Robin

2001-01-01

This 2001 edition of the guide to UK renewable energy companies examines the geothermal heat pump sector, and discusses the technology involved, installations of geothermal heat pumps, the activity in the UK market with increased interest in UK geothermal heat pump products from abroad, and developments in the building sector. The UK government's increased support for the industry including its sponsorship of the Affordable Warmth programme, and the future potential of ground source systems are discussed

Shifts of heat availability and stressful temperatures in Russian Federation result in gains and losses of wheat thermal suitability

Science.gov (United States)

Di Paola, Arianna; Caporaso, Luca; Santini, Monia; Di Paola, Francesco; Vasenev, Ivan; Valentini, Riccardo

2017-04-01

Climate changes are likely to shift the suitability of lands devoted to cropping systems. We explored the past-to-future thermal suitability of Russian Federation for wheat (Triticum aestivum) culture through an ensemble of bias corrected CMIP5-GCMs outputs considering two representative concentration pathways (RCP 4.5 and 8.5). Thermal suitability assesses where wheat heat requirement, counted from suggested sowing dates, is satisfied without the occurrence of stressful hot and frost temperatures. Thermal requirement was estimated by means of phenological observations on soft wheat involving different wheat cultivar collected in different regions of Russian Federation, Azerbaidhan, Kazakhstan and Tadzhikistan, whilst stressful temperatures were taken from a literature survey. Results showed projected geographical shift of heat resource toward the north-eastern regions, currently mainly covered by forests and croplands, but also an increase of very hot temperatures in the most productive areas of the southern regions. Gains and losses were then quantified and discussed from both agronomical and climatic perspective.

Subpicosecond gain dynamics in GaAlAs laser diodes

Energy Technology Data Exchange (ETDEWEB)

Kesler, M.P.; Ippen, E.P.

1987-11-30

Ultrafast gain dynamics in GaAlAs diode amplifiers have been studied using 100 fs optical pulses. Pulse propagation through the amplifier resulted in temporal broadening and pulse shaping due to both gain saturation and material dispersion. Pump-probe experiments indicate the presence of two processes contributing to the gain dynamics but give no evidence of spectral hole burning. A dynamic carrier heating model is presented to explain all of the observed gain nonlinearities, and the implications of our results on the dynamic response of laser diodes are discussed.

A Methodology to Link the Internal Heat Gains from Lighting to the Global Consumption for the Energy Certification of Buildings in Italy

Directory of Open Access Journals (Sweden)

Valerio R.M. Lo Verso

2014-12-01

Full Text Available This paper critically discusses the procedure prescribed by the Italian Technical Standards to account for the internal gains in the calculation of the energy performance indices for a building. This procedure is based on a tabular value set depending on the building usage only (e.g., 6 W/m2 for office buildings, independently of the site and of the controls for blinds and lighting systems. Instead, the paper proposes a new procedure, which relies on the lighting energy numerical indicator (LENI according to the European Standard EN 15193:2007. Basically, the procedure consists of the following steps: 1 internal gains from lighting are calculated accounting for the integration between electric appliances and daylighting; 2 these gains are summed to the internal gains from occupants and appliances; 3 the global gains are used as input data to calculate the energy performance indices for an office building (for space heating, space cooling, and lighting consumption following the Italian Technical Standards. The office building which was used as case-study is the Department of Energy of the Politecnico di Torino. This was assumed to be located both in Turin (northern Italy and in Palermo (southern Italy. In the study, the use of a manual on/off switch and of a photodimming sensor was also compared. For each configuration, the single and the global energy performance indices were calculated comparing two approaches to calculate the internal gains (Italian standard vs. new proposed procedure: a shift of one energy class for the building energy label was observed depending on the approach, which was used.

Can LENR Energy Gains Exceed 1000?

Science.gov (United States)

Nagel, David J.

2011-03-01

Energy gain is defined as the energy realized from reactions divided by the energy required to produce those reactions. Low Energy Nuclear Reactions (LENR) have already been measured to significantly exceed the energy gain of 10 projected from ITER,possibly 15 years from now. Electrochemical experiments using the Pd-D system have shown energy gains exceeding 10. Gas phase experiments with the Ni-H system were reported to yield energy gains of over 100. Neither of these reports has been adequately verified or reproduced. However, the question in the title still deserves consideration. If, as thought by many, it is possible to trigger nuclear reactions that yield MeV energies with chemical energies of the order of eV, then the most optimistic expectation is that LENR gains could approach one million. Hence, the very tentative answer to the question above is yes. However, if LENR could be initiated with some energy cost, and then continue to ``burn,'' very high energy gains might be realized. Consider a match and a pile of dry logs. The phenomenon termed ``heat after death'' will be examined to see if it might be the initial evidence for nuclear ``burning.''

Optimal heat rejection pressure in transcritical carbon dioxide air conditioning and heat pump systems

DEFF Research Database (Denmark)

Liao, Shengming; Jakobsen, Arne

1998-01-01

Due to the urgent need for environmentally benign refrigerants, the use of the natural substance carbon dioxide in refrigeration systems has gained more and more attention. In systems such as automobile air-conditioners and heat pumps, owing to the relatively high heat rejection temperatures, the...... dioxide air conditioning or heat pump systems and for intelligent controlling such systems.......Due to the urgent need for environmentally benign refrigerants, the use of the natural substance carbon dioxide in refrigeration systems has gained more and more attention. In systems such as automobile air-conditioners and heat pumps, owing to the relatively high heat rejection temperatures......, the cycles using carbon dioxide as refrigerant will have to operate in the transcritical area. In a transcritical carbon dioxide system, there is an optimal heat rejection pressure that gives a maximum COP. In this paper, it is shown that the value of this optimal heat rejection pressure mainly depends...

Heating and Domestic Hot Water Systems in Buildings Supplied by Low-Temperature District Heating

DEFF Research Database (Denmark)

Brand, Marek

solutions simply redirect the bypassed water back to the DH network without additional cooling, but bypassed water can instead be redirected to floor heating in the bathroom to be further cooled and thus reduce heat loss from the DH network while improving comfort for occupants and still ensure fast DHW...... increased risk of Legionella if the DH substation and DHW system are designed for the low-temperature supply conditions. To ensure the fast provision of DHW during non-heating periods, the supply service pipe should be kept warm, preferably with the bypass solution redirecting the bypass flow to bathroom...... temperature. To accord with the literature, the modelling of internal heat gains reflected the improved efficiency of equipment by reduction of value from 5W/m2 to 4.2W/m2, also modelled as intermittent heat gains based on a realistic week schedule. Furthermore, the indoor set-point temperature was increased...

Waste heat of HTR power stations for district heating

International Nuclear Information System (INIS)

Bonnenberg, H.; Schlenker, H.V.

1975-01-01

The market situation, the applied techniques, and the transport, for district heating in combination with HTR plants are considered. Analysis of the heat market indicates a high demand for heat at temperatures between 100 and 150 0 C in household and industry. This market for district heating can be supplied by heat generated in HTR plants using two methods: (1) the combined heat and power generation in steam cycle plants by extracting steam from the turbine, and (2) the use of waste heat of a closed gas turbine cycle. The heat generation costs of (2) are negligible. The cost for transportation of heat over the average distance between existing plant sites and consumer regions (25 km) are between 10 and 20% of the total heat price, considering the high heat output of nuclear power stations. Comparing the price of heat gained by use of waste heat in HTR plants with that of conventional methods, considerable advantages are indicated for the combined heat and power generation in HTR plants. (author)

Experience gained at the CEA by thermal effluent utilization for agriculture and fish-breeding

International Nuclear Information System (INIS)

Balligand.

1976-01-01

Results obtained at the CEA for waste heat utilization are examined. Water at T+10 0 C is used for open air soil heating (forest, agriculture), eel breeding and greenhouse, heating (with the help of heat pumps). Water at T+23 0 C or 30 0 C is used for greenhouses. Facilities are described experience gained and results of the different exploitations are given [fr

Study on high gain broadband optical parametric chirped pulse amplification

International Nuclear Information System (INIS)

Zhang, S.K.; Fujita, M.; Yamanaka, C.; Yoshida, H.; Kodama, R.; Fujita, H.; Nakatsuka, M.; Izawa, Y.

2000-01-01

Optical parametric chirped pulse amplification has apparent advantages over the current schemes for high energy ultrashort pulse amplification. High gain in a single pass amplification, small B-integral, low heat deposition, high contrast ratio and, especially the extremely broad gain bandwidth with large-size crystals available bring people new hope for over multi-PW level at which the existing Nd:glass systems suffered difficulties. In this paper we present simulation and experimental studies for a high gain optical parametric chirped pulse amplification system which may be used as a preamplifier to replace the current complicated regenerative system or multi-pass Ti:sapphire amplifiers. Investigations on the amplification bandwidth and gain with BBO are performed. Analysis and discussions are also given. (author)

Experimental evaluation of heat transfer coefficients between radiant ceiling and room

DEFF Research Database (Denmark)

Causone, Francesco; Corgnati, Stefano P.; Filippi, Marco

2009-01-01

The heat transfer coefficients between radiant surfaces and room are influenced by several parameters: surfaces temperature distributions, internal gains, air movements. The aim of this paper is to evaluate the heat transfer coefficients between radiant ceiling and room in typical conditions...... of occupancy of an office or residential building. Internal gains were therefore simulated using heated cylinders and heat losses using cooled surfaces. Evaluations were developed by means of experimental tests in an environmental chamber. Heat transfer coefficient may be expressed separately for radiation...

Low-energy office buildings using existing technology. Simulations with low internal heat gains

Energy Technology Data Exchange (ETDEWEB)

Flodberg, Kajsa; Blomsterberg, Aake; Dubois, Marie-Claude [Lund Univ. (Sweden). Div. of Energy and Building Design

2012-11-01

Although low-energy and nearly zero-energy residential houses have been built in Sweden in the past decade, there are very few examples of low-energy office buildings. This paper investigates the design features affecting energy use in office buildings and suggests the optimal low-energy design from a Swedish perspective. Dynamic simulations have been carried out with IDA ICE 4 on a typical narrow office building with perimeter cell rooms. The results from the parametric study reveal that the most important design features for energy saving are demand-controlled ventilation as well as limited glazing on the facade. Further energy-saving features are efficient lighting and office equipment which strongly reduce user-related electricity and cooling energy. Together, the simulation results suggest that about 48% energy can be saved compared to a new office building built according to the Swedish building code. Thus, it is possible, using a combination of simple and well-known building technologies and configurations, to have very low energy use in new office buildings. If renewable energy sources, such as solar energy and wind power, are added, there is a potential for the annual energy production to exceed the annual energy consumption and a net zero-energy building can be reached. One aspect of the results concerns user-related electricity, which becomes a major energy post in very low-energy offices and which is rarely regulated in building codes today. This results not only in high electricity use, but also in large internal heat gains and unnecessary high cooling loads given the high latitude and cold climate. (orig.)

German central solar heating plants with seasonal heat storage

Energy Technology Data Exchange (ETDEWEB)

Bauer, D.; Marx, R.; Nussbicker-Lux, J.; Ochs, F.; Heidemann, W. [Institute of Thermodynamics and Thermal Engineering (ITW), University of Stuttgart, Pfaffenwaldring 6, D-70550 Stuttgart (Germany); Mueller-Steinhagen, H. [Institute of Thermodynamics and Thermal Engineering (ITW), University of Stuttgart, Pfaffenwaldring 6, D-70550 Stuttgart (Germany); Institute of Technical Thermodynamics (ITT), German Aerospace Centre (DLR), Stuttgart (Germany)

2010-04-15

Central solar heating plants contribute to the reduction of CO{sub 2}-emissions and global warming. The combination of central solar heating plants with seasonal heat storage enables high solar fractions of 50% and more. Several pilot central solar heating plants with seasonal heat storage (CSHPSS) built in Germany since 1996 have proven the appropriate operation of these systems and confirmed the high solar fractions. Four different types of seasonal thermal energy stores have been developed, tested and monitored under realistic operation conditions: Hot-water thermal energy store (e.g. in Friedrichshafen), gravel-water thermal energy store (e.g. in Steinfurt-Borghorst), borehole thermal energy store (in Neckarsulm) and aquifer thermal energy store (in Rostock). In this paper, measured heat balances of several German CSHPSS are presented. The different types of thermal energy stores and the affiliated central solar heating plants and district heating systems are described. Their operational characteristics are compared using measured data gained from an extensive monitoring program. Thus long-term operational experiences such as the influence of net return temperatures are shown. (author)

Urban district heating using nuclear heat - a survey

International Nuclear Information System (INIS)

Beresovski, T.; Oliker, I.

1979-01-01

The use of heat from nuclear power plants is of great interest in connection with projected future expansions of large urban district heating systems. Oil price escalation and air pollution from increased burning of fossil fuels are substantial incentivers for the adoption of nuclear heat and power plants. The cost of the hot water piping system from the nuclear plant to the city is a major factor in determining the feasibility of using nuclear heat. To achieve reasonable costs, the heat load should be at least 1500 MW(th), transport temperatures 125-200 0 C and distances preferably 50 km or less. Heat may be extracted from the turbines of conventional power reactors. Alternatively, some special-purpose smaller reactors are under development which are specially suited to production of heat with little or no power coproduct. Many countries are conducting studies of future expansions of district heating systems to use nuclear heat. Several countries are developing technology suitable for this application. Actual experience with the use of nuclear heat for district heating is currently being gained only in the USSR, however. While district heating appears to be a desirable technology at a time of increasing fossil-fuel costs, the use of nuclear heat will require siting of nuclear plants within transmission radius of cities. The institutional barries toward use of nuclear heating will have to be overcome before the energy conservation potential of this approach can be realized on a significant scale. (author)

Efficiency gains in Danish district heating. Is there anything to learn from benchmarking?

DEFF Research Database (Denmark)

Munksgaard, Jesper; Pade, Lise-Lotte; Fristrup, P.

2005-01-01

Facing a market structure of independent heating systems and cost-of-service regulation the regulator considers ways to create incentives for increasing efficiency in heat production.One way is to implement benchmark regulation. The aim of this paper is twofold: (1) To investigate the potential f...

Self-Heating Effects In Polysilicon Source Gated Transistors

Science.gov (United States)

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

Temporal Gain Correction for X-Ray Calorimeter Spectrometers

Science.gov (United States)

Porter, F. S.; Chiao, M. P.; Eckart, M. E.; Fujimoto, R.; Ishisaki, Y.; Kelley, R. L.; Kilbourne, C. A.; Leutenegger, M. A.; McCammon, D.; Mitsuda, K.

2016-01-01

Calorimetric X-ray detectors are very sensitive to their environment. The boundary conditions can have a profound effect on the gain including heat sink temperature, the local radiation temperature, bias, and the temperature of the readout electronics. Any variation in the boundary conditions can cause temporal variations in the gain of the detector and compromise both the energy scale and the resolving power of the spectrometer. Most production X-ray calorimeter spectrometers, both on the ground and in space, have some means of tracking the gain as a function of time, often using a calibration spectral line. For small gain changes, a linear stretch correction is often sufficient. However, the detectors are intrinsically non-linear and often the event analysis, i.e., shaping, optimal filters etc., add additional non-linearity. Thus for large gain variations or when the best possible precision is required, a linear stretch correction is not sufficient. Here, we discuss a new correction technique based on non-linear interpolation of the energy-scale functions. Using Astro-HSXS calibration data, we demonstrate that the correction can recover the X-ray energy to better than 1 part in 104 over the entire spectral band to above 12 keV even for large-scale gain variations. This method will be used to correct any temporal drift of the on-orbit per-pixel gain using on-board calibration sources for the SXS instrument on the Astro-H observatory.

Analytical models of Ohmic heating and conventional heating in food processing

Science.gov (United States)

Serventi, A.; Bozzoli, F.; Rainieri, S.

2017-11-01

Ohmic heating is a food processing operation in which an electric current is passed through a food and the electrical resistance of the food causes the electric power to be transformed directly into heat. The heat is not delivered through a surface as in conventional heat exchangers but it is internally generated by Joule effect. Therefore, no temperature gradient is required and it origins quicker and more uniform heating within the food. On the other hand, it is associated with high energy costs and its use is limited to a particular range of food products with an appropriate electrical conductivity. Sterilization of foods by Ohmic heating has gained growing interest in the last few years. The aim of this study is to evaluate the benefits of Ohmic heating with respect to conventional heat exchangers under uniform wall temperature, a condition that is often present in industrial plants. This comparison is carried out by means of analytical models. The two different heating conditions are simulated under typical circumstances for the food industry. Particular attention is paid to the uniformity of the heat treatment and to the heating section length required in the two different conditions.

Heat extraction from turbines of Czechoslovak nuclear power plants for district heating

International Nuclear Information System (INIS)

Drahy, J.

1985-01-01

Two design are described of SKODA extraction turbines for Czechoslovak nuclear power plants with WWER-440 and WWER-1000 reactors. 220 MW steam turbines were originally designed as pure condensation turbines with uncontrolled steam extraction. Optimal ways are now being sought for their use for heating hot water for district heating. For district heating of the town of Trnava, the nuclear power plant at Jaslovske Bohunice will provide a two-step heating of water from 70 to 120 degC with a heat supply of 60 MW th from one turbine unit. The ratio of obtained heat power to lost electric power is 5.08. Investigations showed the possibility of extracting 85 MW th of heat from uncontrolled steam extraction, this at three-step water heating from 60 to 145 degC, the ratio of gained and lost power being 7.14. Information is presented on the SKODA 220 MW turbine with steam extraction for heat supply purposes and on the 1000 MW turbine with 893 MW th heat extraction. The specifications of both types are given. (Pu)

Receiver gain function: the actual NMR receiver gain

OpenAIRE

Mo, Huaping; Harwood, John S.; Raftery, Daniel

2010-01-01

The observed NMR signal size depends on the receiver gain parameter. We propose a receiver gain function to characterize how much the raw FID is amplified by the receiver as a function of the receiver gain setting. Although the receiver is linear for a fixed gain setting, the actual gain of the receiver may differ from what the gain setting suggests. Nevertheless, for a given receiver, we demonstrate that the receiver gain function can be calibrated. Such a calibration enables accurate compar...

Nova Upgrade: A proposed ICF facility to demonstrate ignition and gain, revision 1

Science.gov (United States)

1992-07-01

The present objective of the national Inertial Confinement Fusion (ICF) Program is to determine the scientific feasibility of compressing and heating a small mass of mixed deuterium and tritium (DT) to conditions at which fusion occurs and significant energy is released. The potential applications of ICF will be determined by the resulting fusion energy yield (amount of energy produced) and gain (ratio of energy released to energy required to heat and compress the DT fuel). Important defense and civilian applications, including weapons physics, weapons effects simulation, and ultimately the generation of electric power will become possible if yields of 100 to 1,000 MJ and gains exceeding approximately 50 can be achieved. Once ignition and propagating bum producing modest gain (2 to 10) at moderate drive energy (1 to 2 MJ) has been achieved, the extension to high gain (greater than 50) is straightforward. Therefore, the demonstration of ignition and modest gain is the final step in establishing the scientific feasibility of ICF. Lawrence Livermore National Laboratory (LLNL) proposes the Nova Upgrade Facility to achieve this demonstration by the end of the decade. This facility would be constructed within the existing Nova building at LLNL for a total cost of approximately $400 M over the proposed FY 1995-1999 construction period. This report discusses this facility.

A comparison of the heat and mechanical energy of a heat-pump wind turbine system

Energy Technology Data Exchange (ETDEWEB)

Aybek, A.; Arslan, S.; Yildiz, E.; Atik, K. [University of Kahramanmaras (Turkey). Dept. of Agricultural Machinery

2000-07-01

While a variety of applications of wind energy have been studied in Turkey, no significant efforts have been made to utilize heat pumps for heat generation. The use of heat pumps in wind energy systems is worth considering because of the high efficiency of heat production. In this study, a directly coupled wind turbine-heat pump system was designed, constructed, and tested. Measurements determined the mechanical energy of the rotors of the wind turbine and the heat energy generated by the heat pump driven by the rotor shaft. Based on the comparisons between the power generated by the heat pump and the power of the Savonius rotors, it was found that the heat energy gained by the heat pump was four times greater than the mechanical energy obtained from the turbine. It was suggested that heat pumps could be efficiently used in wind energy systems. (Author)

Efficiency gains of photovoltaic system using latent heat thermal energy storage

NARCIS (Netherlands)

Tan, Lippong; Date, Abhijit; Fernandes, Gabriel; Singh, Baljit; Ganguly, Sayantan

This paper presents experimental assessments of the thermal and electrical performance of photovoltaic (PV) system by comparing the latent heat-cooled PV panel with the naturally-cooled equivalent. It is commonly known that the energy conversion efficiency of the PV cells declines with the increment

Nutritional evaluation of heat treated sunflower meal on the performance of broiler chicks

International Nuclear Information System (INIS)

Ali, S.; Kausar, T.; Shah, W.H.

2004-01-01

Pre-pressed and solvent extracted sunflower meal (SFM) was heated to 90 degree, 100 degree, 110 degree and 120 degree C. Lysine content of SFM decreased from 2.25 to 1.60%. The untreated and heat treated SFM was incorporated in broiler's ration. Maximum weight gain (1525g) and feed efficiency (2.24) were shown by the ration containing SFM heated to 90 degree, which was better than the control ration (weight gain 1454g, feed efficiency 2038). Processing of SFM at higher temperature (100 - 120 degree C) adversely affected weight gain (1388 - 1315g) and feed efficiency (2.46-251). (author)

Radiant Heating and Cooling Systems. Part two

DEFF Research Database (Denmark)

Kim, Kwan Woo; Olesen, Bjarne W.

2015-01-01

Control of the heating and cooling system needs to be able to maintain the indoor temperatures within the comfort range under the varying internal loads and external climates. To maintain a stable thermal environment, the control system needs to maintain the balance between the heat gain...

Soft measures and incremental gains in mines; Mesures douces et gains incrementaux : mines

Energy Technology Data Exchange (ETDEWEB)

Laliberte, P. [Natural Resources Canada, Ottawa, ON (Canada). CANMET Mining and Mineral Sciences Laboratories

2008-07-01

This paper presented a variety of measures that mine operators can adopt to save energy. Researchers at the CANMET Mining and Mineral Sciences Laboratories of Natural Resources Canada have conducted a joint study with Hydro-Quebec to investigate the impact of alternate energy technologies and control systems on energy savings. The impacts of a range of technologies were evaluated and rates of energy efficiency were compared. Technologies included hybrid vehicles; fuel cell-powered vehicles; automated ventilation control systems; heat recovery; compressed air; and electrical mining equipment. Energy profiles for various industrial applications were included. This paper also provided details of computerized simulations currently being conducted to estimate the potential incremental gains associated with the use of technology innovations in mining applications. 9 tabs., 3 figs.

Energy efficiency of gas engine driven heat pumps for heating and cooling applications; Energieeffizienter Einsatz von Gasmotorwaermepumpen fuer Heiz- und Kuehlanwendungen

Energy Technology Data Exchange (ETDEWEB)

Schmidt, Juergen [Magdeburg Univ. (Germany). Inst. fuer Stroemungstechnik und Thermodynamik

2012-11-15

Heat pumps are gaining in importance for a sustainable and ecological heat supply. Gas engine driven systems can contribute to a decentralized energy supply by power heat cogeneration. In the paper, a pilot plant, which offers high energy efficiency by simultaneous use of the heat of evaporation and condensation, is presented. The plant permits the testing of different operating modes and obtains high values above three for the primary energy ratio. (orig.)

Nuclear heat applications in Russia: Experience, status and prospects

International Nuclear Information System (INIS)

Mitenkov, F.M.; Kusmartsev, E.V.

1998-01-01

The extensive experience gained with nuclear district heating in Russia is described. Most of the WWER reactors in Russia are cogeneration plants. Steam is extracted through LP turbine bleeders and condensed in intermediate heat exchangers to hot water which is then supplied to DH grids. Also some small dedicated nuclear heating plants are operated. (author)

Cutaneous C-polymodal fibers lacking TRPV1 are sensitized to heat following inflammation, but fail to drive heat hyperalgesia in the absence of TPV1 containing C-heat fibers

Directory of Open Access Journals (Sweden)

Koerber H Richard

2010-09-01

Full Text Available Abstract Background Previous studies have shown that the TRPV1 ion channel plays a critical role in the development of heat hyperalgesia after inflammation, as inflamed TRPV1-/- mice develop mechanical allodynia but fail to develop thermal hyperalgesia. In order to further investigate the role of TRPV1, we have used an ex vivo skin/nerve/DRG preparation to examine the effects of CFA-induced-inflammation on the response properties of TRPV1-positive and TRPV1-negative cutaneous nociceptors. Results In wildtype mice we found that polymodal C-fibers (CPMs lacking TRPV1 were sensitized to heat within a day after CFA injection. This sensitization included both a drop in average heat threshold and an increase in firing rate to a heat ramp applied to the skin. No changes were observed in the mechanical response properties of these cells. Conversely, TRPV1-positive mechanically insensitive, heat sensitive fibers (CHs were not sensitized following inflammation. However, results suggested that some of these fibers may have gained mechanical sensitivity and that some previous silent fibers gained heat sensitivity. In mice lacking TRPV1, inflammation only decreased heat threshold of CPMs but did not sensitize their responses to the heat ramp. No CH-fibers could be identified in naïve nor inflamed TRPV1-/- mice. Conclusions Results obtained here suggest that increased heat sensitivity in TRPV1-negative CPM fibers alone following inflammation is insufficient for the induction of heat hyperalgesia. On the other hand, TRPV1-positive CH fibers appear to play an essential role in this process that may include both afferent and efferent functions.

Angular spectrum characters of high gain non-critical phase match optical parametric oscillators

International Nuclear Information System (INIS)

Liu Jian-Hui; Liu Qiang; Gong Ma-Li

2011-01-01

The angular spectrum gain characters and the power magnification characters of high gain non-walk-off colinear optical parametric oscillators have been studied using the non-colinear phase match method for the first time. The experimental results of the KTiOAsO 4 and the KTiOPO 4 crystals are discussed in detail. At the high energy single resonant condition, low reflective ratio of the output mirror for the signal and long non-linear crystal are beneficial for small divergence angles. This method can also be used for other high gain non-walk-off phase match optical parametric processes. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

Economic and safety aspects of using moderator heat for feed water heating in a nuclear power plant

International Nuclear Information System (INIS)

Patwegar, I.A.; Dutta, Anu; Chaki, S.K.; Venkat Raj, V.

2002-01-01

Full text: In the proposed advanced heavy water reactor (AHWR), coolant and moderator are separated by the coolant channel. The coolant absorbs most of the fission heat produced in the reactor core. However, the moderator absorbs about 5 to 6 % of the fission heat. In a reactor producing 750 MW(th) power, this moderator heat is about 40 MW. In the present Indian PHWR (pressurized heavy water reactor) systems, this moderator heat is lost to a sink through the moderator heat exchangers, which are cooled by process water. This paper presents the results of the steam cycle analysis carried out for AHWR using moderator heat exchangers as part of the feed heating system. The present study is an attempt to determine the gain in electrical output (MW) if moderator heat is utilized for feed water heating. The operational and safety aspects of using moderator heat are also discussed in the paper

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

International Nuclear Information System (INIS)

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

2016-01-01

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. - Highlights: • Spin-valve effect of heat generation happens when Coulomb repulsion in quantum dot is less than phonon frequency. • When Coulomb repulsion is larger than phonon frequency, inverse spin-valve effect appears and is enlarged with bias increasing. • The variation of spin polarization degree can change heat generation effectively. • The heat magnetoresistance can be modulated from heat-resistance to heat-gain by gate voltage easily.

Experience gained from high heat flux actively cooled PFCs in Tore Supra

International Nuclear Information System (INIS)

Grosman, A.; Bayetti, P.; Brosset, C.; Bucalossi, J.; Cordier, J.J.; Durocher, A.; Escourbiac, F.; Ghendrih, Ph.; Guilhem, D.; Gunn, J.; Loarer, T.; Lipa, M.; Mitteau, R.; Pegourie, B.; Reichle, R.; Schlosser, J.; Tsitrone, E.; Vallet, J.C.

2005-01-01

The implementation of actively cooled high heat flux plasma facing components (PFCs) is one of the major ingredients required for operating the Tore Supra tokamak with very long pulses. A pioneering activity has been developed in this field from the very beginning of the device operation that is today culminating with the routine operation of an actively cooled toroidal pumped limiter (TPL) capable to sustain up to 10 MW/m 2 of nominal convected heat flux. Technical information is drawn from the whole development up to the industrialisation and focuses on a number of critical issues, such as bonding technology analysis, manufacture processes, repair processes, destructive and non-destructive testing. The actual experience in Tore Supra allows to address the question of D retention on carbon walls. Redeposition on surfaces without plasma flux is suspected to cause the final 'burial' of about half of the injected gas during long discharges

Magnetic induced heating of nanoparticle solutions

Energy Technology Data Exchange (ETDEWEB)

Murph, S. Hunyadi [Savannah River Site (SRS), Aiken, SC (United States); Univ. of Georgia, Athens, GA (United States); Brown, M. [Savannah River Site (SRS), Aiken, SC (United States); Coopersmith, K. [Savannah River Site (SRS), Aiken, SC (United States); Fulmer, S. [Savannah River Site (SRS), Aiken, SC (United States); Sessions, H. [Savannah River Site (SRS), Aiken, SC (United States); Ali, M. [Univ. of South Carolina, Columbia, SC (United States)

2016-12-02

Magnetic induced heating of nanoparticles (NP) provides a useful advantage for many energy transfer applications. This study aims to gain an understanding of the key parameters responsible for maximizing the energy transfer leading to nanoparticle heating through the use of simulations and experimental results. It was found that magnetic field strength, NP concentration, NP composition, and coil size can be controlled to generate accurate temperature profiles in NP aqueous solutions.

Pulse Combustor Driven Pressure Gain Combustion for High Efficiency Gas Turbine Engines

KAUST Repository

Lisanti, Joel

2017-02-01

The gas turbine engine is an essential component of the global energy infrastructure which accounts for a significant portion of the total fossil fuel consumption in transportation and electric power generation sectors. For this reason there is significant interest in further increasing the efficiency and reducing the pollutant emissions of these devices. Conventional approaches to this goal, which include increasing the compression ratio, turbine inlet temperature, and turbine/compressor efficiency, have brought modern gas turbine engines near the limits of what may be achieved with the conventionally applied Brayton cycle. If a significant future step increase in gas turbine efficiency is to be realized some deviation from this convention is necessary. The pressure gain gas turbine concept is a well established new combustion technology that promises to provide a dramatic increase in gas turbine efficiency by replacing the isobaric heat addition process found in conventional technology with an isochoric process. The thermodynamic benefit of even a small increase in stagnation pressure across a gas turbine combustor translates to a significant increase in cycle efficiency. To date there have been a variety of methods proposed for achieving stagnation pressure gains across a gas turbine combustor and these concepts have seen a broad spectrum of levels of success. The following chapter provides an introduction to one of the proposed pressure gain methods that may be most easily realized in a practical application. This approach, known as pulse combustor driven pressure gain combustion, utilizes an acoustically resonant pulse combustor to approximate isochoric heat release and thus produce a rise in stagnation pressure.

Summary of Pressure Gain Combustion Research at NASA

Science.gov (United States)

Perkins, H. Douglas; Paxson, Daniel E.

2018-01-01

NASA has undertaken a systematic exploration of many different facets of pressure gain combustion over the last 25 years in an effort to exploit the inherent thermodynamic advantage of pressure gain combustion over the constant pressure combustion process used in most aerospace propulsion systems. Applications as varied as small-scale UAV's, rotorcraft, subsonic transports, hypersonics and launch vehicles have been considered. In addition to studying pressure gain combustor concepts such as wave rotors, pulse detonation engines, pulsejets, and rotating detonation engines, NASA has studied inlets, nozzles, ejectors and turbines which must also process unsteady flow in an integrated propulsion system. Other design considerations such as acoustic signature, combustor material life and heat transfer that are unique to pressure gain combustors have also been addressed in NASA research projects. In addition to a wide range of experimental studies, a number of computer codes, from 0-D up through 3-D, have been developed or modified to specifically address the analysis of unsteady flow fields. Loss models have also been developed and incorporated into these codes that improve the accuracy of performance predictions and decrease computational time. These codes have been validated numerous times across a broad range of operating conditions, and it has been found that once validated for one particular pressure gain combustion configuration, these codes are readily adaptable to the others. All in all, the documentation of this work has encompassed approximately 170 NASA technical reports, conference papers and journal articles to date. These publications are very briefly summarized herein, providing a single point of reference for all of NASA's pressure gain combustion research efforts. This documentation does not include the significant contributions made by NASA research staff to the programs of other agencies, universities, industrial partners and professional society

Low-temperature nuclear heat applications: Nuclear power plants for district heating

International Nuclear Information System (INIS)

1987-08-01

The IAEA reflected the needs of its Member States for the exchange of information in the field of nuclear heat application already in the late 1970s. In the early 1980s, some Member States showed their interest in the use of heat from electricity producing nuclear power plants and in the development of nuclear heating plants. Accordingly, a technical committee meeting with a workshop was organized in 1983 to review the status of nuclear heat application which confirmed both the progress made in this field and the renewed interest of Member States in an active exchange of information about this subject. In 1985 an Advisory Group summarized the Potential of Low-Temperature Nuclear Heat Application; the relevant Technical Document reviewing the situation in the IAEA's Member States was issued in 1986 (IAEA-TECDOC-397). Programme plans were made for 1986-88 and the IAEA was asked to promote the exchange of information, with specific emphasis on the design criteria, operating experience, safety requirements and specifications for heat-only reactors, co-generation plants and power plants adapted for heat application. Because of a growing interest of the IAEA's Member States about nuclear heat employment in the district heating domaine, an Advisory Group meeting was organized by the IAEA on ''Low-Temperature Nuclear Heat Application: Nuclear Power Plants for District Heating'' in Prague, Czechoslovakia in June 1986. The information gained up to 1986 and discussed during this meeting is embodied in the present Technical Document. 22 figs, 11 tabs

Optimal Control of Solar Heating System

KAUST Repository

Huang, Bin-Juine

2017-02-21

Forced-circulation solar heating system has been widely used in process and domestic heating applications. Additional pumping power is required to circulate the water through the collectors to absorb the solar energy. The present study intends to develop a maximum-power point tracking control (MPPT) to obtain the minimum pumping power consumption at an optimal heat collection. The net heat energy gain Qnet (= Qs − Wp/ηe) was found to be the cost function for MPPT. The step-up-step-down controller was used in the feedback design of MPPT. The field test results show that the pumping power is 89 W at Qs = 13.7 kW and IT = 892 W/m2. A very high electrical COP of the solar heating system (Qs/Wp = 153.8) is obtained.

Energy Savings for Solar Heating Systems

DEFF Research Database (Denmark)

Thür, Alexander; Furbo, Simon; Shah, Louise Jivan

2004-01-01

, various simulations of solar heating systems were done for different hot water demands and collector sizes. The result shows that the potential of fuel reduction can be much higher than the solar gain of the solar thermal system. For some conditions the fuel reduction can be up to the double of the solar......In this paper the realistic behaviour and efficiency of heating systems were analysed, based on long term monitoring projects. Based on the measurements a boiler model was evaluated. Comparisons of measured and calculated fuel consumptions showed a good degree of similarity. With the boiler model...... gain due to a strong increase of the system efficiency. As the monitored boilers were not older than 3 years, it can be assumed that the saving potential with older boilers could be even higher than calculated in this paper....

Conceptual design of an active magnetic regenerative heat circulator based on self-heat recuperation technology

International Nuclear Information System (INIS)

Kotani, Yui; Kansha, Yasuki; Tsutsumi, Atsushi

2013-01-01

A conceptual design of an active magnetic regenerative (AMR) heat circulator for self-heat recuperation to realize energy savings in thermal processes is proposed. The process fluid heat is recuperated by the magnetocaloric effect of ferromagnetic material through the AMR heat circulation cycle. In an AMR heat circulator, all the process fluid heat is circulated and no make-up heat is added to raise the process fluid to its set temperature. A one-dimensional mathematical model of the AMR heat circulator was constructed to understand its behavior and verify its energy-saving potential. From the constructed one-dimensional mathematical model, it is seen that AMR heat circulator has potential to drastically reduce the total energy consumption in a thermal process. The temperature–entropy diagram shows that in order to gain the maximum energy saving, optimization of the parameters such as the flow rate and geometry of the ferromagnetic working material beds is needed. - Highlights: • Self-heat recuperative active magnetic regenerative heat circulator is introduced. • One-dimensional model is constructed to verify its energy-saving potential. • Total energy consumption in thermal process is drastically reduced. • Further energy can be saved by reducing the overlapping of thermodynamic cycles

Resveratrol induces antioxidant and heat shock protein mRNA expression in response to heat stress in black-boned chickens.

Science.gov (United States)

Liu, L L; He, J H; Xie, H B; Yang, Y S; Li, J C; Zou, Y

2014-01-01

This study investigated the effects of dietary resveratrol at 0, 200, 400, or 600 mg/kg of diet on the performance, immune organ growth index, serum parameters, and expression levels of heat shock protein (Hsp) 27, Hsp70, and Hsp90 mRNA in the bursa of Fabricius, thymus, and spleen of 42-d-old female black-boned chickens exposed to heat stress at 37 ± 2°C for 15 d. The results showed that heat stress reduced daily feed intake and BW gain; decreased serum glutathione (GSH), growth hormone, and insulin-like growth factor-1 levels; and inhibited GSH peroxidase (GSH-Px), superoxide dismutase (SOD), and catalase (CAT) activities compared with birds subjected to thermo-neutral circumstances. Chickens that were fed diets supplemented with resveratrol exhibited a linear increase in feed intake and BW gain (P stress. In contrast, serum malonaldehyde concentrations were decreased (P stress also reduced (P stress and coincided with an increase in supplemental resveratrol levels. The expression of Hsp27, Hsp70, and Hsp90 mRNA in the bursa of Fabricius and spleen were increased (P stress compared with no heat stress. Resveratrol attenuated the heat stress-induced overexpression of Hsp27, Hsp70, and Hsp90 mRNA in the bursa of Fabricius and spleen and increased the low expression of Hsp27 and Hsp90 mRNA in thymus upon heat stress. The results suggest that supplemental resveratrol improves growth performance and reduces oxidative stress in heat-stressed black-boned chickens by increasing serum growth hormone concentrations and modulating the expression of heat shock genes in organs of the immune system.

Flow visualization in heat-generating porous media

International Nuclear Information System (INIS)

Lee, D.O.; Nilson, R.H.

1977-11-01

The work reported is in support of the Sandia Post-Accident Heat Removal Program, in which simulated LMFBR beds will be subjected to in-pile heating in the ACPR (Annular Core Pulsed Reactor). Flow visualization experiments were performed to gain some insight into the flow patterns and temperature distributions in a fluid-saturated heat-generating porous medium. Although much of the information presented is of a qualitative nature, it is useful in the recognition of the controlling transport process and in the formulation of analytic and numerical models

Quasi-adaptive fuzzy heating control of solar buildings

Energy Technology Data Exchange (ETDEWEB)

Gouda, M.M. [Faculty of Industrial Education, Cairo (Egypt); Danaher, S. [University of Northumbria, Newcastle upon Tyne, (United Kingdom). School of Engineering; Underwood, C.P. [University of Northumbria, Newcastle upon Tyne (United Kingdom). School of Built Environment and Sustainable Cities Research Institute

2006-12-15

Significant progress has been made on maximising passive solar heat gains to building spaces in winter. Control of the space heating in these applications is complicated due to the lagging influence of the useful solar heat gain coupled with the wide range of construction materials and heating system choices. Additionally, and in common with most building control applications, there is a need to develop control solutions that permit simple and transparent set-up and commissioning procedures. This paper addresses the development and testing of a quasi-adaptive fuzzy logic control method that addresses these issues. The controller is developed in two steps. A feed-forward neural network is used to predict the internal air temperature, in which a singular value decomposition (SVD) algorithm is used to remove the highly correlated data from the inputs of the neural network to reduce the network structure. The fuzzy controller is then designed to have two inputs: the first input being the error between the set-point temperature and the internal air temperature and the second the predicted future internal air temperature. The controller was implemented in real-time using a test cell with controlled ventilation and a modulating electric heating system. Results, compared with validated simulations of conventionally controlled heating, confirm that the proposed controller achieves superior tracking and reduced overheating when compared with the conventional method of control. (author)

Calculation Tool for Determining the Net Energy Gain

DEFF Research Database (Denmark)

Laustsen, Jacob Birck; Svendsen, Svend

2002-01-01

is dependent on both the U-values and the g-values. Beyond this it is dependent on the orientation of the windows and the climate and the actual period. This makes it difficult to choose the glazings and windows that are optimal with regard to energy performance in a given case. These facts have aroused a need...... for simple and accurate methods to determine and compare the energy performance of different window products. When choosing windows for new buildings or retrofitting a calculation tool that in a simple way determines the net energy gain from the specific windows in the actual building will ease the selection...... of the best window solution. Such a tool combined with a database with window products can make calculations of the heat loss or energy demand corresponding to the requirements in the new building code easier and more correct. In the paper, methods to determine energy performance data and the net energy gain...

Power-heat coupling plant of the Hacker-Pschorr Braeu AG, Munich

Energy Technology Data Exchange (ETDEWEB)

Treiber, K

1978-01-01

The power-heat co-generation plan of a large-scale brewery is specified. The specific heat consumption, the cost of in-house power generation, and cost savings gained are determined. In-house power costs and extraneous power costs are contrasted.

Exploitation of humid air latent heat by means of solar assisted heat pumps operating below the dew point

International Nuclear Information System (INIS)

Scarpa, Federico; Tagliafico, Luca A.

2016-01-01

Highlights: • The opportunity of humid air latent heat exploitation by DX-SAHP is investigated. • A set of experimental tests confirms this opportunity and quantifies it as relevant. • A parametric analysis is performed, via simulation, to deepen the subject. • The energy gain is relevant during both night and daytime. - Abstract: Nowadays, the exploitation of environmental exergy resources for heating purposes (solar energy, convection heat transfer from ambient air, moist air humidity condensation) by means of properly designed heat pump systems is a possible opportunity. In particular, the use of direct expansion solar assisted heat pumps (DX-SAHP) is investigated in this study, when a bare external plate (the solar collector) is kept at temperatures lower than the dew point temperature of ambient air, so that condensation takes place on it. The potential of this technology is settled and an instrumented prototype of a small DX-SAHP system is used to verify the actual performance of the system, in terms of specific thermal energy delivered to the user, efficiency and regulation capabilities. Results clearly show that the contribution of the condensation is significant (20%–30% of the total harvested energy) overnight or in cloudy days with very low or no solar irradiation, and must be taken into account in a system model devoted to describe the DX-SAHP behavior. During daytime, the percentage gain decreases but is still consistent. By investigating along these lines, the heat due to condensation harvested by the collector is found to be a function of the dew-point temperature alone.

Heat generation: prices have only a minor influence

International Nuclear Information System (INIS)

Stadelmann, M.

2006-01-01

This article takes a look at long-term trends in the heat generation market. Here, heat-pumps, gas heaters and wood-fired systems, together with their combination with solar collectors, are gaining ground, whereas heating oil is loosing its share of the market. The various influences on the market and, in particular, price increases for oil are discussed. The influence of revised energy legislation is discussed, which calls for 20% of the standardised energy requirements of housing to be met by renewables or increased thermal insulation. Increased sales in the solar sector are discussed, as are future trends in the heating market

Three-Dimensional Numerical Simulation of Plate Forming by Line Heating

DEFF Research Database (Denmark)

Clausen, Henrik Bisgaard

1999-01-01

addressed the problem of simulating the process, and although very few have been successful in gaining accurate results valuable information about the mechanics have been derived. However, the increasing power of computers now allows for numerical simulations of the forming process using a three......Line Heating is the process of forming (steel) plates into shape by means of localised heating often along a line. Though any focussed heat source will do, the inexpensive and widely available oxyacettylene gas torch is commonly applied in ship production.Over the years, many researchers have......-dimensional thermo-mechanical model. Although very few have been successful in gaining accurate results valuable information about the mechanics has been derived. However, the increasing power of computers now allows for numerical simulations of the forming process using a three-dimensional thermo-mechanical model....

Procedures for selecting and buying district heating equipment. Sofia district heating. Final report

Energy Technology Data Exchange (ETDEWEB)

NONE

1997-11-01

The aim of this Final Report, prepared for the project `Procedures for Selecting and Buying DistRict Heating Equipment - Sofia District Heating Company`, is to establish an overview of the activities accomplished, the outputs delivered and the general experience gained as a result of the project. The main objective of the project is to enable Sofia District Heating Company to prepare specifications and tender documents, identify possible suppliers, evaluate offers, etc. in connection with purchase of district heating equipment. This objective has been reached by using rehabilitation of sub-stations as an example requested by Sofia DH. The project was originally planned to be finalized end of 1995, but due to the extensions of the scope of work, the project has been prolonged until end 1997. The following main activities were accomplished: Preparation of a detailed work plan; Collection of background information; Discussion and advice about technical specifications and tender documents for sub-station rehabilitation; Input to terms of reference for a master plan study; Input to technical specification for heat meters; Collection of ideas for topics and examples related to dissemination of information to consumers about matters related to district heating consumption. (EG)

A THEORETICAL HEAT ANALYSIS OF BUILDINGS IN SUMMER CONDITION

Directory of Open Access Journals (Sweden)

R. Tuğrul OĞULATA

1997-01-01

Full Text Available It is possible to achive the bio-climatical comfort is buildings by setting the indoor temperature at certain level at which the people feels himself comfortable. The indoor temperature changing with the summer-winter climate conditions and with the building materials should always be around desirable level. Therefore, the variation of indoor temperature depending on the natural and artifical cooling and heating of building materials, within the range of design, is becoming so important. For this reason, in this investigation, the variation of indoor temperature has been analysed considering the variation of heat gain by convection, radiation and infiltration, the heat capacity of materials used in building including the outdoor and the temperature of outer ambient. In addition to this, the variation of indoor temperature with time has been computed under the condition that whether the cooling source exist or not. For this purpose, the heat gains, the indoor and outer temperature, the capacity of cooling system and solar radiation have been expressed analyticaly by transforming them into Fourier series.

Energy Savings for Solar Heating Systems

DEFF Research Database (Denmark)

Thür, Alexander; Furbo, Simon; Shah, Louise Jivan

2006-01-01

showed a good degree of similarity. With the boiler model, various simulations of solar domestic hot water heating systems were done for different hot water demands and collector sizes. The result shows that the potential of fuel reduction can be much higher than the solar gain of the solar thermal...... system. For some conditions the fuel reduction can be up to the double of the solar gain due to a strong increase of the system efficiency. As the monitored boilers were not older than 3 years, it can be assumed that the saving potential with older boilers could be even higher than calculated......In this paper the realistic behaviour and efficiency of heating systems were analysed, based on long term monitoring projects. Based on the measurements a boiler model used to calculate the boiler efficiency on a monthly basis was evaluated. Comparisons of measured and calculated fuel consumptions...

Random walk and the heat equation

CERN Document Server

Lawler, Gregory F

2010-01-01

The heat equation can be derived by averaging over a very large number of particles. Traditionally, the resulting PDE is studied as a deterministic equation, an approach that has brought many significant results and a deep understanding of the equation and its solutions. By studying the heat equation by considering the individual random particles, however, one gains further intuition into the problem. While this is now standard for many researchers, this approach is generally not presented at the undergraduate level. In this book, Lawler introduces the heat equation and the closely related notion of harmonic functions from a probabilistic perspective. The theme of the first two chapters of the book is the relationship between random walks and the heat equation. The first chapter discusses the discrete case, random walk and the heat equation on the integer lattice; and the second chapter discusses the continuous case, Brownian motion and the usual heat equation. Relationships are shown between the two. For exa...

Temperature mapping, thermal diffusivity and subsoil heat flux at ...

Indian Academy of Sciences (India)

R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

vide an understanding of the gain or loss of heat by the soil from the atmosphere. Many studies made earlier have been related to sim- ilar issues such as prediction of soil tempera- tures; heat storage variations; thermal diffusivity of the soil, etc. (Kelkar et al 1980; Chowdhury et al 1991; Lamba and Khambete 1991; Retnaku ...

The largest Swiss diffusion storage system - Geology, petrophysics, hydro-geology and experience gained from the realisation of heat probes; Groesster saisonaler Diffusionsspeicher der Schweiz D4 in Root (LU): Geologie, Petrophysik, Hydrogeologie und Erfahrungen mit der Realisation des Sondenfeldes

Energy Technology Data Exchange (ETDEWEB)

Keller, B.

2007-07-15

This article takes a look at a large heat-diffusion storage system that is to be implemented in stages at a business and innovation centre in Root, near Lucerne in Switzerland. The aim is to meet 50 percent of energy needs using renewable energy. Apart from conventional oil and gas-fired systems, a combined heat and power (CHP) unit, heat and cold storage, a solar roof and photovoltaics, a seasonal underground diffusion storage system is used. This storage system is 'filled' with heat in summer from the roof and waste heat. It then functions in winter as a heat source. The system features two fields of 49, 160 metre-long heat probes that use a volume of 376,000 cubic metres of rock. The dimensioning of the rock-storage system was simulated using the PILESIM program and the first field was implemented in 2001. A geological overview is presented and the physical properties of the rock structures used are discussed. The temperature profile measured is presented and the precautions taken as a result of the possibility of meeting pockets of natural gas are discussed. Know-how gained from the implementation of the first probe field is discussed.

Seasonal variability of heat flux divergence in the coastal waters of Visakhapatnam

Digital Repository Service at National Institute of Oceanography (India)

Rao, B.P.; Sadhuram, Y.

Heat flux divergence (Qv) in the coastal waters of Visakhapatnam, Andhra, Pradesh, India during different seasons, was estimated for the period February 1980-January 1981. It is found that the water column (0-60 m) gains heat during winter...

Heat budget parameters for the southwestern Arabian Sea during monsoon - 88 experiment

Digital Repository Service at National Institute of Oceanography (India)

RameshBabu, V.; Gopalakrishna, V.V.; Sastry, J.S.

. The cooling in the upper layers is partly accountEd. by the surface heat exchange processes and the subsurface heat gain suggests the influence of sinking motion in the study area wherein the dynamic topography field is predominantly characterised...

Quantum heat engines and refrigerators: continuous devices.

Science.gov (United States)

Kosloff, Ronnie; Levy, Amikam

2014-01-01

Quantum thermodynamics supplies a consistent description of quantum heat engines and refrigerators up to a single few-level system coupled to the environment. Once the environment is split into three (a hot, cold, and work reservoir), a heat engine can operate. The device converts the positive gain into power, with the gain obtained from population inversion between the components of the device. Reversing the operation transforms the device into a quantum refrigerator. The quantum tricycle, a device connected by three external leads to three heat reservoirs, is used as a template for engines and refrigerators. The equation of motion for the heat currents and power can be derived from first principles. Only a global description of the coupling of the device to the reservoirs is consistent with the first and second laws of thermodynamics. Optimization of the devices leads to a balanced set of parameters in which the couplings to the three reservoirs are of the same order and the external driving field is in resonance. When analyzing refrigerators, one needs to devote special attention to a dynamical version of the third law of thermodynamics. Bounds on the rate of cooling when Tc→0 are obtained by optimizing the cooling current. All refrigerators as Tc→0 show universal behavior. The dynamical version of the third law imposes restrictions on the scaling as Tc→0 of the relaxation rate γc and heat capacity cV of the cold bath.

Gestational weight gain.

Science.gov (United States)

Kominiarek, Michelle A; Peaceman, Alan M

2017-12-01

Prenatal care providers are advised to evaluate maternal weight at each regularly scheduled prenatal visit, monitor progress toward meeting weight gain goals, and provide individualized counseling if significant deviations from a woman's goals occur. Today, nearly 50% of women exceed their weight gain goals with overweight and obese women having the highest prevalence of excessive weight gain. Risks of inadequate weight gain include low birthweight and failure to initiate breast-feeding whereas the risks of excessive weight gain include cesarean deliveries and postpartum weight retention for the mother and large-for-gestational-age infants, macrosomia, and childhood overweight or obesity for the offspring. Prenatal care providers have many resources and tools to incorporate weight and other health behavior counseling into routine prenatal practices. Because many women are motivated to improve health behaviors, pregnancy is often considered the optimal time to intervene for issues related to eating habits and physical activity to prevent excessive weight gain. Gestational weight gain is a potentially modifiable risk factor for a number of adverse maternal and neonatal outcomes and meta-analyses of randomized controlled trials report that diet or exercise interventions during pregnancy can help reduce excessive weight gain. However, health behavior interventions for gestational weight gain have not significantly improved other maternal and neonatal outcomes and have limited effectiveness in overweight and obese women. Copyright © 2017 Elsevier Inc. All rights reserved.

Operational gain : measuring the capture of genetic gain ...

African Journals Online (AJOL)

The concept of operational gain is more than the weighted average of the genetic quality of planted hectares, and encompasses tree breeding efficiencies, propagation efficiencies, matching of species and genotype to site, plant use efficiency and early measures of stand density and growth. To test the operational gain ...

A parametric study of a humidification dehumidification (HDH) desalination system using low grade heat sources

International Nuclear Information System (INIS)

He, W.F.; Han, D.; Yue, C.; Pu, W.H.

2015-01-01

Highlights: • The HDH desalination system coupling with the waste heat plate LGHC is proposed. • Performance of the desalination system and the plate LGHC is presented. • Influence from the operation pressure on the system performance is investigated. • Gained investment ratio is proposed to characterize the desalination system consumption. - Abstract: Humidification dehumidification (HDH) desalination system is applicable to recover the low grade heat source to heat the seawater before the humidifier. In the paper, plate heat exchangers are integrated to recover the waste heat from the exhaust in the water heated closed air open water (CAOW) HDH desalination system. The performance of the HDH desalination system as well as the plate type of low grade heat collector (LGHC) is investigated at different operation pressures. Gain investment ratio (GIR) is proposed and defined to depict the overall consumption of the whole system. The simulation results show that the modified heat capacity ratio of the dehumidifier (HCRd) is vital for the performance of the HDH desalination system as well as the plate LGHC with a top value of gain output ratio (GOR) at the balance point, HCRd = 1, and the maximum GOR, GOR = 2.44, results from the raised pressure of p = 0.15 MPa. Furthermore, taking the cost for the heat transfer surface area of the LGHC and the air and seawater pipes into consideration, it is revealed that the conditions, HCRd > 1, are more economical due to the increase of GIR, which indicates the profit of unit consumption is more significant.

Performance of RF power and phase control on JT-60 LHRF heating system

International Nuclear Information System (INIS)

Fujii, T.; Ikeda, Y.; Imai, T.; Honda, M.; Kiyono, K.; Maebara, S.; Saigusa, M.; Sakamoto, K.; Sawahata, M.; Seki, M.

1987-01-01

The performance of RF power and phase control on the JT-60 LHRFD heating system are presented. The JT-60 LHRF heating system has three units of huge RF source with a total output of 24 MW, each unit consisting of eight amplifier chains. A high power klystron generating 1 MW for 10 s at 2 GHz is used in each chain. Automatic gain control is employed to regulate the output power not only against gain fluctuations in the chain but also against the unstable plasma load without any output circulator for the klystron

Numerical simulation of the effect of hydrogen on recombination gain in the transition to ground state of Li III

International Nuclear Information System (INIS)

Avitzour, Yoav; Suckewer, Szymon

2006-01-01

Numerical simulations of recombination gain in the Li III transition to ground state (2→1 at 13.5 nm) are presented. The plasma simulated is a mixture of Li and H ions, and the space-time-dependent gain coefficient is calculated for different mixing ratios and different pumping beam parameters. The numerical model includes the initial optical field ionization of the plasma by an intense 100 fs laser pulse, taking into account residual heating, particle collisions, and spatial effects. Gain is then calculated during the process of recombination as the plasma expands and cools. We show that the addition of hydrogen to the plasma can lead to higher gain with a less restrictive range of experimental parameters. We analyze the effects of the addition of hydrogen on the gain and point to the optimal plasma and pump parameters to produce gain

Efficiency of two-step solar thermochemical non-stoichiometric redox cycles with heat recovery

International Nuclear Information System (INIS)

Lapp, J.; Davidson, J.H.; Lipiński, W.

2012-01-01

Improvements in the effectiveness of solid phase heat recovery and in the thermodynamic properties of metal oxides are the most important paths to achieving unprecedented thermal efficiencies of 10% and higher in non-stoichiometric solar redox reactors. In this paper, the impact of solid and gas phase heat recovery on the efficiency of a non-stoichiometric cerium dioxide-based H 2 O/CO 2 splitting cycle realized in a solar-driven reactor are evaluated in a parametric thermodynamic analysis. Application of solid phase heat recovery to the cycling metal oxide allows for lower reduction zone operating temperatures, simplifying reactor design. An optimum temperature for metal oxide reduction results from two competing phenomena as the reduction temperature is increased: increasing re-radiation losses from the reactor aperture and decreasing heat loss due to imperfect solid phase heat recovery. Additionally, solid phase heat recovery increases the efficiency gains made possible by gas phase heat recovery. -- Highlights: ► Both solid and gas phase heat recovery are essential to achieve high thermal efficiency in non-stoichiometric ceria-based solar redox reactors. ► Solid phase heat recovery allows for lower reduction temperatures and increases the gains made possible by gas phase heat recovery. ► The optimum reduction temperature increases with increasing concentration ratio and decreasing solid phase heat recovery effectiveness. ► Even moderate levels of heat recovery dramatically improve reactor efficiency from 3.5% to 16%.

Heat release from wood wall assemblies using oxygen consumption method

Science.gov (United States)

Hao C. Tran; Robert E. White

1990-01-01

The concept of heat release rate is gaining acceptance in the evaluation of fire performance of materials and assemblies. However, this concept has not been incorporated into fire endurance testing such as the ASTM E-119 test method. Heat release rate of assemblies can be useful in determining the time at which the assemblies start to contribute to the controlled fire...

Comparative economic performance of selected passive solar heating and cooling technologies

Science.gov (United States)

Rutter, W.

1981-05-01

The economic performance of selected passive solar heating and cooling technologies which incorporate energy storage is assessed by using a set of uniform assumptions and methodologies. Where data are available, a given system is assessed at more than one geographical location. Results are obtained in the form of both payback period and net present value for residential applications, and in terms of net present value only for industrial/commercial uses. Results indicate that ventilated trombe walls, solar roof ponds, and certain night effect/floor storage strategies are cost effective, but night effect/rock bed cooling is not. Results also show that, although direct gain out-performs trombe walls in most parts of the country, both direct gain and trombe walls usually produce a net savings in the residential sector. Generally, however, tax regulations result in net economic loss for direct gain and trombe walls used to heat industrial and commercial buildings.

MOS current gain cells with electronically variable gain and constant bandwidth

NARCIS (Netherlands)

Klumperink, Eric A.M.; Seevinck, Evert

1989-01-01

Two MOS current gain cells are proposed that provide linear amplification of currents supplied by several linear MOS V-I converters. The gain is electronically variable by a voltage or a current and can be made insensitive to temperature and IC processing. The gain cells have a constant

The influence of a vertical ground heat exchanger length on the electricity consumption of the heat pumps

Energy Technology Data Exchange (ETDEWEB)

Michopoulos, A.; Kyriakis, N. [Process Equipment Design Laboratory, Mechanical Engineer Department, Aristotle University of Thessaloniki (AUTh), P.O. Box 487, 541 24 Thessaloniki (Greece)

2010-07-15

The use of heat pumps combined with vertical ground heat exchangers for heating and cooling of buildings, has significantly gained popularity in recent years. The design method for these systems, as it is proposed by ASHRAE, is taking into account the maximum thermal and cooling loads of the building, the thermophysical properties of the soil at the area of installation and a minimum Coefficient of Performance (COP) of the heat pumps. This approach usually results in larger than needed length of the ground heat exchanger, thus increasing the installation cost. A new analytical simulation tool, capable to determine the required ground heat exchanger length has been developed at the Process Equipment Design Laboratory (PEDL) of the AUTh. It models the function of the system as a whole over long time periods, e.g. 20 years, using as input parameters the thermal and cooling loads of the building, the thermophysical properties of the borehole and the characteristic curves of the heat pumps. The results include the electricity consumption of the heat pumps and the heat absorbed from or rejected to the ground. The aim of this paper is to describe the developed simulation algorithm and present the results of such a simulation in a case study. It is proved that the total required length of the ground heat exchanger is less than that calculated using the common numerical method. (author)

The economics of supplying the supplementary heat in a closed loop water source heat pump system

International Nuclear Information System (INIS)

Johnson, R.P.; Bartkus, V.E.; Singh, J.B.

1993-01-01

The paper describes the details of a research and demonstration project that will be completed in August 1992 at a healthcare facility in northeastern Pennsylvania. The purpose of the project is to compare the economics of several methods of supplying the supplementary heating in a facility served by a closed loop water source heat pump system. The systems being tested include a storage hot water tank with electric resistance heaters and three air source heat pumps that have the ability to supply the same heat during on-peak hours as well as off-peak hours. The paper compares the projected operating costs of the following: (1) Gas boiler supplying the supplementary heat. (2) Stored hot water supplying the supplementary heat which is generated and stored during off-peak hours using resistance heat on PP ampersand L's offpeak rate. (3) Stored hot water supplying the supplementary heat generated during off-peak hours using the air source heat pumps on PP ampersand L's off-peak rate. (4) Hot water generated by the air source heat pumps supplying the supplementary loop heating on PP ampersand L's general service and time-of-day electric rates. It is generally known in the HVAC industry that a closed loop water source heat pump system can provide one of the most efficient means of space conditioning to a building with high internal gains by transferring the excess heat available in one part of the building to another part of the building where it may be needed for heating. The following flow diagram depicts the relationship of the air source heat pumps with the storage tanks and the building closed water loop

Ground source heat pumps designed for earth-sheltered, low-energy atrium building

NARCIS (Netherlands)

Pawlovski, A.; Heim, D.; Hensen, J.L.M.

2003-01-01

One of the main strategies in design of earth-sheltered buildings is to reduce heat losses in the winter and heat gains in the summer by using the relatively stable thermal conditions of the soil. Additionally, construction work carried out at the site allows a reduction of the installation costs

Electron heating and energy inventory during asymmetric reconnection in a laboratory plasma

Science.gov (United States)

Yoo, J.; Na, B.; Jara-Almonte, J.; Yamada, M.; Ji, H.; Roytershteyn, V.; Argall, M. R.; Fox, W.; Chen, L. J.

2017-12-01

Electron heating and the energy inventory during asymmetric reconnection are studied in the Magnetic Reconnection Experiment (MRX) [1]. In this plasma, the density ratio is about 8 across the current sheet. Typical features of asymmetric reconnection such as the large density gradients near the low-density-side separatrices, asymmetric in-plane electric field, and bipolar out-of-plane magnetic field are observed. Unlike the symmetric case [2], electrons are also heated near the low-density-side separatrices. The measured parallel electric field may explain the observed electron heating. Although large fluctuations driven by lower-hybrid drift instabilities are also observed near the low-density-side separatrices, laboratory measurements and numerical simulations reported here suggest that they do not play a major role in electron energization. The average electron temperature increase in the exhaust region is proportional to the incoming magnetic energy per an electron/ion pair but exceeds the scaling of the previous space observations [3]. This discrepancy is explained by differences in the boundary condition and system size. The profile of electron energy gain from the electric field shows that there is additional electron energy gain associated with the electron diamagnetic current besides a large energy gain near the X-line. This additional energy gain increases electron enthalpy, not the electron temperature. Finally, a quantitative analysis of the energy inventory during asymmetric reconnection is conducted. Unlike the symmetric case where the ion energy gain is about twice more than the electron energy gain [4], electrons and ions obtain a similar amount of energy during asymmetric reconnection. [1] J. Yoo et al., accepted for a publication in J. Geophys. Res. [2] J. Yoo et al., Phys. Plasmas 21, 055706 (2014). [3] T. Phan et al., Geophys. Res. Lett. 40, 4475 (2013). [4] M. Yamada et al., Nat. Comms. 5, 4474 (2014).

Optical gain and gain suppression of quantum-well lasers with valence band mixing

International Nuclear Information System (INIS)

Ahn, D.; Chuang, S.L.

1990-01-01

The effects of valence band mixing on the nonlinear gains of quantum-well lasers are studied theoretically. The authors' analysis is based on the multiband effective-mass theory and the density matrix formalism with intraband relaxation taken into account. The gain and the gain-suppression coefficient of a quantum-well laser are calculated from the complex optical susceptibility obtained by the density matrix formulation with the theoretical dipole moments obtained from the multiband effective-mass theory. The calculated gain spectrum shows that there are remarkable differences (both in peak amplitude and spectral shape) between our model with valence band mixing and the conventional parabolic band model. The shape of the gain spectrum calculated by the authors' model becomes more symmetric due to intraband relaxation together with nonparabolic energy dispersions and is closer to the experimental observations when compared with the conventional method using the parabolic band model and the multiband effective-mass calculation without intraband relaxation. Both give quite asymmetric gain spectra. Optical intensity in the GaAs active region is estimated by solving rate equations for the stationary states with nonlinear gain suppression. The authors calculate the mode gain for the resonant mode including the gain suppression, which results in spectral hole burning of the gain spectrum

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

Science.gov (United States)

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 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 heating the GHP house was significantly lower (P heating system for broiler chickens.

Heat pumps barometer - EurObserv'ER 2016

International Nuclear Information System (INIS)

2016-01-01

The heat pump (HP) sector had an excellent year in 2015. Appliance sales taking all heating and cooling market technologies into account, increased by 20% from 2212898 units in 2014 to 2655331 units in 2015. The emerging trend over the past few years specific to the HP segment for water-borne systems is that air-source HPs are clearly gaining market shares to the detriment of the ground-source HP market, while reversible HPs using air as their vector are taking advantage of record temperatures that have given a boost to the cooling market

Effects of heat stress on baroreflex function in humans

Science.gov (United States)

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.

End users heat energy savings using thermostat regulation valves radiators, v. 16(64)

International Nuclear Information System (INIS)

Jakimovska, Emilija Misheva; Potsev, Eftim

2008-01-01

Billing the used heat energy offers the opportunity to motivate end users to use the heat energy rationally and to save the energy. Installing the thermostat valves on the radiators it is possible frequently to regulate the room temperature and to use the heat gains, obtaining comfortable climate in the apartments and saving the energy. Thermostat valves give the possibility to use the heat energy rationally and save the energy, and these way and users can regulate the heat energy consumption according to their own level of thermal comfort. (Author)

End users heat energy savings using thermostat regulation valves radiators, v. 16(63)

International Nuclear Information System (INIS)

Jakimovska, Emilija Misheva; Potsev, Eftim

2008-01-01

Billing the used heat energy offers the opportunity to motivate end users to use the heat energy rationally and to save the energy. Installing the thermostat valves on the radiators it is possible frequently to regulate the room temperature and to use the heat gains, obtaining comfortable climate in the apartments and saving the energy. Thermostat valves give the possibility to use the heat energy rationally and save the energy, and these way and users can regulate the heat energy consumption according to their own level of thermal comfort. (Author)

Heat-deproteinated xenogeneic bone from slaughterhouse waste ...

Indian Academy of Sciences (India)

Unknown

Xenogeneic bone procured from the slaughterhouse waste was deproteinated by heat treatment method intended for use as a bone ... bone resembles hydroxyapatite (HA) with composition,. Ca10(PO4)6(OH)2. HA is a potential implant .... order to obtain antigenic-free inorganic bone minerals. To gain information about the ...

Benefits of Integrating Geographically Distributed District Heating Systems

DEFF Research Database (Denmark)

Dominkovic, Dominik Franjo; Bačeković, I.; Sveinbjörnsson, Dadi Þorsteinn

2016-01-01

Although liberalization of the electricity day-ahead markets has gained pace throughout the Europe, district heating markets are often dominated by lack of competition between suppliers, which curbs the potential of having cheaper systems in terms of socio-economic costs, and technically better s...

Liquid-Crystal Display (LCD) Screen Thermal Testing to Simulate Solar Gain

Science.gov (United States)

2015-12-01

determined that shielding the screen from solar gains was the best way to avoid monitor failure. In order to accomplish this Hot Mirror glass from...side of the monitor in order to shield the monitor from the solar loading. 2.7 Test 7 – Bench Test with a 250 W Heat Lamp and Hot Mirror Glass , 1 Inch...method to shield the screen from solar loading. The Hot Mirror glass uses a glass substrate with a coating on 1 side that passes visible light, but

A quantitative determination of air-water heat fluxes in Hermit Lake, New Hampshire under varying meteorological conditions, time of day, and time of year

Science.gov (United States)

Kyper, Nicholas D.

An extensive heat flux study is performed at Hermit Lake, New Hampshire from May 26, 2010 till November 7, 2010 to determine the effects of the five individual heat fluxes on Hermit Lake and the surrounding amphibian community. Hermit Lake was chosen due to the relatively long meteorological observations record within the White Mountains of New Hampshire, a new lakeside meteorological station, and ongoing phenology studies of the surrounding eco-system. Utilizing meteorological data from the lakeside weather station and moored water temperature sensors, the incident (Qi), blackbody ( Qbnet ), latent (Qe), sensible (Q s), and net (Qn) heat fluxes are calculated. The incident heat flux is the dominate term in the net flux, accounting for 93% of the variance found in Qn and producing a heat gain of ˜ 19x108 J m-2 throughout the period of study. This large gain produces a net gain of heat in the lake until October 1, 2010, where gains by Qi are offset by the large combined losses of Qbnet , Qs, and Qe thereby producing a gradual decline of heat within the lake. The latent and blackbody heat fluxes produce the largest losses of heat in the net heat flux with a total losses of ˜ -8x108 J m-2 and ˜ -7x108 J m-2, respectively. The sensible heat flux is negligible, producing a total minimal loss of ˜ -1x108 J m-2. Overall the net heat produces a net gain of heat of 2x108 J m-2 throughout the study period. Frog calls indicative of breeding are recorded from May 26, 2010 until August 16, 2010. The spring peeper, American toad, and green frog each produced enough actively calling days to be compared to air temperature, surface water temperature, and wind speed data, as well as data from the five heat fluxes. Linear regression analysis reveals that certain water temperature thresholds affect the calling activities of the spring peeper and green frog, while higher wind speeds have a dramatic effect on the calling activities of both the green frog and American toad. All three

Low-Cost Gas Heat Pump for Building Space Heating

Energy Technology Data Exchange (ETDEWEB)

Garrabrant, Michael [Stone Mountain Technologies, Inc., Johnson City, TN (United States); Keinath, Christopher [Stone Mountain Technologies, Inc., Johnson City, TN (United States)

2016-10-11

, which will allow for improved load matching. In addition, the energy savings analysis showed that a house in Albany, NY, Chicago, IL and Minneapolis, MN would save roughly 32, 28.5 and 36.5 MBtu annually when compared to a 100% efficient boiler, respectively. The gas absorption heat pump achieves this performance by using high grade heat from the combustion of natural gas in combination with low grade heat extracted from the ambient to produce medium grade heat suitable for space and water heating. Expected product features include conventional outdoor installation practices, 4:1 modulation, and reasonable economic payback. These factors position the technology to gain significant market penetration, resulting in a large reduction of energy use and greenhouse gas emissions for residential space heating.

Should I Gain Weight?

Science.gov (United States)

... Videos for Educators Search English Español Should I Gain Weight? KidsHealth / For Teens / Should I Gain Weight? ... something about it. Why Do People Want to Gain Weight? Some of the reasons people give for ...

Heat generation above break-even from laser-induced fusion in ultra-dense deuterium

Directory of Open Access Journals (Sweden)

Leif Holmlid

2015-08-01

Full Text Available Previous results from laser-induced processes in ultra-dense deuterium D(0 give conclusive evidence for ejection of neutral massive particles with energy >10 MeV u−1. Such particles can only be formed from nuclear processes like nuclear fusion at the low laser intensity used. Heat generation is of interest for future fusion energy applications and has now been measured by a small copper (Cu cylinder surrounding the laser target. The temperature rise of the Cu cylinder is measured with an NTC resistor during around 5000 laser shots per measured point. No heating in the apparatus or the gas feed is normally used. The fusion process is suboptimal relative to previously published studies by a factor of around 10. The small neutral particles HN(0 of ultra-dense hydrogen (size of a few pm escape with a substantial fraction of the energy. Heat loss to the D2 gas (at <1 mbar pressure is measured and compensated for under various conditions. Heat release of a few W is observed, at up to 50% higher energy than the total laser input thus a gain of 1.5. This is uniquely high for the use of deuterium as fusion fuel. With a slightly different setup, a thermal gain of 2 is reached, thus clearly above break-even for all neutronicity values possible. Also including the large kinetic energy which is directly measured for MeV particles leaving through a small opening gives a gain of 2.3. Taking into account the lower efficiency now due to the suboptimal fusion process, previous studies indicate a gain of at least 20 during long periods.

Developmental gains in visuospatial memory predict gains in mathematics achievement.

Directory of Open Access Journals (Sweden)

Yaoran Li

Full Text Available Visuospatial competencies are related to performance in mathematical domains in adulthood, but are not consistently related to mathematics achievement in children. We confirmed the latter for first graders and demonstrated that children who show above average first-to-fifth grade gains in visuospatial memory have an advantage over other children in mathematics. The study involved the assessment of the mathematics and reading achievement of 177 children in kindergarten to fifth grade, inclusive, and their working memory capacity and processing speed in first and fifth grade. Intelligence was assessed in first grade and their second to fourth grade teachers reported on their in-class attentive behavior. Developmental gains in visuospatial memory span (d = 2.4 were larger than gains in the capacity of the central executive (d = 1.6 that in turn were larger than gains in phonological memory span (d = 1.1. First to fifth grade gains in visuospatial memory and in speed of numeral processing predicted end of fifth grade mathematics achievement, as did first grade central executive scores, intelligence, and in-class attentive behavior. The results suggest there are important individual differences in the rate of growth of visuospatial memory during childhood and that these differences become increasingly important for mathematics learning.

Developmental gains in visuospatial memory predict gains in mathematics achievement.

Science.gov (United States)

Li, Yaoran; Geary, David C

2013-01-01

Visuospatial competencies are related to performance in mathematical domains in adulthood, but are not consistently related to mathematics achievement in children. We confirmed the latter for first graders and demonstrated that children who show above average first-to-fifth grade gains in visuospatial memory have an advantage over other children in mathematics. The study involved the assessment of the mathematics and reading achievement of 177 children in kindergarten to fifth grade, inclusive, and their working memory capacity and processing speed in first and fifth grade. Intelligence was assessed in first grade and their second to fourth grade teachers reported on their in-class attentive behavior. Developmental gains in visuospatial memory span (d = 2.4) were larger than gains in the capacity of the central executive (d = 1.6) that in turn were larger than gains in phonological memory span (d = 1.1). First to fifth grade gains in visuospatial memory and in speed of numeral processing predicted end of fifth grade mathematics achievement, as did first grade central executive scores, intelligence, and in-class attentive behavior. The results suggest there are important individual differences in the rate of growth of visuospatial memory during childhood and that these differences become increasingly important for mathematics learning.

Developmental Gains in Visuospatial Memory Predict Gains in Mathematics Achievement

Science.gov (United States)

Li, Yaoran; Geary, David C.

2013-01-01

Visuospatial competencies are related to performance in mathematical domains in adulthood, but are not consistently related to mathematics achievement in children. We confirmed the latter for first graders and demonstrated that children who show above average first-to-fifth grade gains in visuospatial memory have an advantage over other children in mathematics. The study involved the assessment of the mathematics and reading achievement of 177 children in kindergarten to fifth grade, inclusive, and their working memory capacity and processing speed in first and fifth grade. Intelligence was assessed in first grade and their second to fourth grade teachers reported on their in-class attentive behavior. Developmental gains in visuospatial memory span (d = 2.4) were larger than gains in the capacity of the central executive (d = 1.6) that in turn were larger than gains in phonological memory span (d = 1.1). First to fifth grade gains in visuospatial memory and in speed of numeral processing predicted end of fifth grade mathematics achievement, as did first grade central executive scores, intelligence, and in-class attentive behavior. The results suggest there are important individual differences in the rate of growth of visuospatial memory during childhood and that these differences become increasingly important for mathematics learning. PMID:23936154

Waste heat and water recovery opportunities in California tomato paste processing

International Nuclear Information System (INIS)

Amón, Ricardo; Maulhardt, Mike; Wong, Tony; Kazama, Don; Simmons, Christopher W.

2015-01-01

Water and energy efficiency are important for the vitality of the food processing industry as demand for these limited resources continues to increase. Tomato processing, which is dominated by paste production, is a major industry in California – where the majority of tomatoes are processed in the United States. Paste processing generates large amounts of condensate as moisture is removed from the fruit. Recovery of the waste heat in this condensate and reuse of the water may provide avenues to decrease net energy and water use at processing facilities. However, new processing methods are needed to create demand for the condensate waste heat. In this study, the potential to recover condensate waste heat and apply it to the tomato enzyme thermal inactivation processing step (the hot break) is assessed as a novel application. A modeling framework is established to predict heat transfer to tomatoes during the hot break. Heat recovery and reuse of the condensate water are related to energy and monetary savings gained through decreased use of steam, groundwater pumping, cooling towers, and wastewater processing. This analysis is informed by water and energy usage data from relevant unit operations at a commercial paste production facility. The case study indicates potential facility seasonal energy and monetary savings of 7.3 GWh and $166,000, respectively, with most savings gained through reduced natural gas use. The sensitivity of heat recovery to various process variables associated with heat exchanger design and processing conditions is presented to identify factors that affect waste heat recovery. - Highlights: • The potential to recovery waste heat in tomato paste processing is examined. • Heat transfer from evaporator condensate to tomatoes in the hot break is modeled. • Processing facility data is used in model to predict heat recovery energy savings. • The primary benefit of heat recovery is reduced use of natural gas in boilers. • Reusing

Detective quantum efficiency gains compared with speed gains for hypersensitized astronomical plates

International Nuclear Information System (INIS)

Kaye, A.L.

1977-01-01

It is reasonable to assume that gains in detective quantum efficiency (DQE) are far better criteria for assessing the performance of hypersensitizing techniques than gains in speed. It is shown here that gains in speed can be misleading, for some methods of hypersensitization give plates of increased speed but reduced detective quantum efficiency. (author)

Thermal load forecasting in district heating networks using deep learning and advanced feature selection methods

NARCIS (Netherlands)

Suryanarayana, Gowri; Lago Garcia, J.; Geysen, Davy; Aleksiejuk, Piotr; Johansson, Christian

2018-01-01

Recent research has seen several forecasting methods being applied for heat load forecasting of district heating networks. This paper presents two methods that gain significant improvements compared to the previous works. First, an automated way of handling non-linear dependencies in linear

Essentials of radiation heat transfer

CERN Document Server

Balaji

2014-01-01

Essentials of Radiation Heat Transfer is a textbook presenting the essential, fundamental information required to gain an understanding of radiation heat transfer and equips the reader with enough knowledge to be able to tackle more challenging problems. All concepts are reinforced by carefully chosen and fully worked examples, and exercise problems are provided at the end of every chapter. In a significant departure from other books on this subject, this book completely dispenses with the network method to solve problems of radiation heat transfer in surfaces. It instead presents the powerful radiosity-irradiation method and shows how this technique can be used to solve problems of radiation in enclosures made of one to any number of surfaces. The network method is not easily scalable. Secondly, the book introduces atmospheric radiation, which is now being considered as a potentially important area, in which engineers can contribute to the technology of remote sensing and atmospheric sciences in general, b...

Preventing Weight Gain

Science.gov (United States)

... Local Programs Related Topics Diabetes Nutrition Preventing Weight Gain Language: English (US) Español (Spanish) Recommend on Facebook ... cancer. Choosing an Eating Plan to Prevent Weight Gain So, how do you choose a healthful eating ...

Optimal waste heat recovery and reuse in industrial zones

International Nuclear Information System (INIS)

Stijepovic, Mirko Z.; Linke, Patrick

2011-01-01

Significant energy efficiency gains in zones with concentrated activity from energy intensive industries can often be achieved by recovering and reusing waste heat between processing plants. We present a systematic approach to target waste heat recovery potentials and design optimal reuse options across plants in industrial zones. The approach first establishes available waste heat qualities and reuse feasibilities considering distances between individual plants. A targeting optimization problem is solved to establish the maximum possible waste heat recovery for the industrial zone. Then, a design optimization problem is solved to identify concrete waste heat recovery options considering economic objectives. The paper describes the approach and illustrates its application with a case study. -- Highlights: → Developed a systematic approach to target waste heat recovery potentials and to design optimal recovery and reuse options across plants in industrial zones. → Five stage approach involving data acquisition, analysis, assessment, targeting and design. → Targeting optimization problem establishes the maximum possible waste heat recovery and reuse limit for the industrial zone. → Design optimization problem provides concrete waste heat recovery and reuse network design options considering economic objectives.

Numerical study of an innovative design of a finned double-pipe heat exchanger with variable fin-tip thickness

International Nuclear Information System (INIS)

Syed, K.S.; Ishaq, Muhammad; Iqbal, Zafar; Hassan, Ahmad

2015-01-01

Highlights: • Variable fin tip angle significantly effect the velocity and temperature distribution. • Significant gain in the thermal performance with decrease in the friction factor. • Variable fin tip angle must be considered an important parameter in designing finned annulus. - Abstract: The analysis of fully developed laminar convective heat transfer in an innovate design of a finned double-pipe heat exchanger (DPHE) with longitudinal fins of variable thickness of the tip subjected to the constant heat transfer rate boundary conditions is investigated here. The tip thickness is controlled by the ratio of tip to base angles as a parameter whose values varying from 0 to 1 correspond to the fin shapes varying from the triangular to the rectangular cross-section. Upto the knowledge of the authors, this parameter is being introduced for the first time in the literature. Discontinuous Galerkin finite element method (DG-FEM) has been employed in the present work. The overall performance of the proposed DPHE has been investigated by considering the friction factor, the Nusselt number and the j-factor. Upto 178% gain in the Nusselt number and 89% gain in the j-factor have been achieved relative to the rectangular cross-section. Such gains relative to the triangular cross-section are respectively 9.5% and 19%. The results indicate that the newly introduced parameter the ratio of tip to base angles has proved to play significant role in the design of a double-pipe heat exchanger in reducing the cost, weight and frictional loss, in improving the heat transfer rate and making the exchanger energy-efficient. Therefore, it must be considered as an important design parameter for heat exchanger design

Comprehensive thermodynamic analysis of a renewable energy sourced hybrid heating system combined with latent heat storage

International Nuclear Information System (INIS)

Utlu, Zafer; Aydın, Devrim; Kıncay, Olcay

2014-01-01

Highlights: • An experimental thermal investigation of hybrid renewable heating system is presented. • Analyses were done by using real data obtained from a prototype structure. • Exergy efficiency of system components investigated during discharging period are close to each other as 32%. • The average input energy and exergy rates to the LHS were 0.770 and 0.027 kW. • Overall total energy and exergy efficiencies of LHS calculated as 72% and 28.4%. - Abstract: In this study an experimental thermal investigation of hybrid renewable heating system is presented. Latent heat storage stores energy, gained by solar collectors and supplies medium temperature heat to heat pump both day time also night time while solar energy is unavailable. In addition to this an accumulation tank exists in the system as sensible heat storage. It provides supply–demand balance with storing excess high temperature heat. Analyses were done according to thermodynamic’s first and second laws by using real data obtained from a prototype structure, built as part of a project. Results show that high percent of heat loses took place in heat pump with 1.83 kW where accumulator-wall heating cycle followed it with 0.42 kW. Contrarily highest break-down of exergy loses occur accumulator-wall heating cycle with 0.28 kW. Averagely 2.42 kW exergy destruction took place in whole system during the experiment. Solar collectors and heat pump are the promising components in terms of exergy destruction with 1.15 kW and 1.09 kW respectively. Exergy efficiency of system components, investigated during discharging period are in a close approximately of 32%. However, efficiency of solar collectors and charging of latent heat storage are 2.3% and 7% which are relatively low. Average overall total energy and exergy efficiencies of latent heat storage calculated as 72% and 28.4% respectively. Discharging energy efficiency of latent heat storage is the highest through all system components. Also heat

Corrosion resistance of structural material AlMg-2 in water following heat treatment and cooling

International Nuclear Information System (INIS)

Maman Kartaman A; Djoko Kisworo; Dedi Hariyadi; Sigit

2005-01-01

Corrosion tests of structural material AlMg-2 in water were carried out using autoclave in order to study the effects of heat treatment on the corrosion resistance of the material. Prior to the tests, the samples were heat-treated at temperatures of 90, 200, 300 and 500 °C and cooled in air, sand and water. The corrosion tests were conducted in water at temperature of 150 °C for 250 hours. The results showed that AlMg-2 samples were corroded although the increase of mass gain was relatively small. Heat treatment from 90 to 500 °C in sand cooling media resulted in an increase of mass gain despite that at 300 °C the increase was less than those at 200 °C and 500 °C. For water cooling media in the temperature range of 90 to 200 °C, the mass gain increased from 0.1854 g/cm 2 to 2.1204 g/cm 2 although after 200 °C it decreased to 1.8207 g/cm 2 and 1.6779 g/cm 2 respectively. For air cooling media, the mass gain was relatively constant. Based on the experiment results, it can be concluded that heat treatment and cooling did not significantly influence the corrosion resistance of material AlMg-2. The passive film Al 2 O 3 on the surface was able to protect the inner surface from further corrosion. Water media with pH range from 4 – 9 did not cause damage to passive layer formed. (author)

Influences of finite gain bandwidth on pulse propagation in parabolic fiber amplifiers with distributed gain profiles

International Nuclear Information System (INIS)

Zhao Jia-Sheng; Li Pan; Chen Xiao-Dong; Feng Su-Juan; Mao Qing-He

2012-01-01

The evolutions of the pulses propagating in decreasing and increasing gain distributed fiber amplifiers with finite gain bandwidths are investigated by simulations with the nonlinear Schrödinger equation. The results show that the parabolic pulse propagations in both the decreasing and the increasing gain amplifiers are restricted by the finite gain bandwidth. For a given input pulse, by choosing a small initial gain coefficient and gain variation rate, the whole gain for the pulse amplification limited by the gain bandwidth may be higher, which is helpful for the enhancement of the output linearly chirped pulse energy. Compared to the decreasing gain distributed fiber amplifier, the increasing gain distributed amplifier may be more conducive to suppress the pulse spectral broadening and increase the critical amplifier length for achieving a larger output linearly chirped pulse energy

Applications of artificial neural networks for thermal analysis of heat exchangers - A review

International Nuclear Information System (INIS)

Mohanraj, M.; Jayaraj, S.; Muraleedharan, C.

2015-01-01

Artificial neural networks (ANN) have been widely used for thermal analysis of heat exchangers during the last two decades. In this paper, the applications of ANN for thermal analysis of heat exchangers are reviewed. The reported investigations on thermal analysis of heat exchangers are categorized into four major groups, namely (i) modeling of heat exchangers, (ii) estimation of heat exchanger parameters, (iii) estimation of phase change characteristics in heat exchangers and (iv) control of heat exchangers. Most of the papers related to the applications of ANN for thermal analysis of heat exchangers are discussed. The limitations of ANN for thermal analysis of heat exchangers and its further research needs in this field are highlighted. ANN is gaining popularity as a tool, which can be successfully used for the thermal analysis of heat exchangers with acceptable accuracy. (authors)

The Consequences of Unpredictable Development of Economic Conditions on Heat Exchanger Network Configurations and Economic Results

DEFF Research Database (Denmark)

Mou, C.; Qvale, Einar Bjørn

2002-01-01

streams. The primary objective of the present work was to gain an understanding of the influence of dramatic economic changes on heat exchanger network (HEN) configurations, their profitability and how an existing HEN could restrict future possibilities of heat recovery. HENs were designed to maximise...

Heat pumps in Denmark - From ugly duckling to white swan

DEFF Research Database (Denmark)

Nyborg, Sophie; Røpke, Inge

2015-01-01

Over the last 10 years, the smart grid and heat pumps have increasingly gained attention in Denmark as an integral part of the low carbon transition of the energy system. The main reason being that the smart grid enables the integration of large amounts of intermittent wind energy...... into the electricity system via, among other things, intelligent interoperation with domestic heat pumps, which consume the 'green' electricity. Unfortunately, recent years' sales of heat pumps have been disappointing. Several studies have investigated the 'dissemination potential' of heat pumps in Denmark, primarily...... through conventional market research approaches. However, there is clearly a lack of studies that take a more socio-technical approach to understanding how technologies such as the heat pump develop and how they come to have a place in society as a result of contingent, emergent and complex historical...

Spectral hole-burning and carrier-heating dynamics in quantum-dot amplifiers: Comparison with bulk amplifiers

DEFF Research Database (Denmark)

Borri, P.; Langbein, W.; Hvam, Jørn Märcher

2001-01-01

The ultrafast gain dynamics in an electrically pumped InAs/InGaAs/GaAs quantum-dot amplifier are measured at room temperature with femtosecond resolution, and compared with results on an InGaAsP bulk amplifier. The role of spectral hole burning and carrier heating in the recovery of the gain...

Inkjet printing of novel wideband and high gain antennas on low-cost paper substrate

KAUST Repository

Cook, Benjamin Stassen

2012-09-01

A complete characterization of the inkjet printing process using metallic nanoparticle inks on a paper substrate for microwave frequencies up to 12.5 GHz as well as its application to low-cost, high gain and wideband antenna design are demonstrated in this work. Laser and heat sintering of metallic nanoparticles are compared on paper substrate for the first time which demonstrate immense cost and time benefits of laser sintering. The antennas fabricated using the characterized process include a Vivaldi for the UWB band which exhibits a significantly higher gain of up to 8 dBi as compared to the currently published inkjet printed antennas, and a novel slow-wave log periodic dipole array which employs a new miniaturization technique to show 20% width reduction. © 1963-2012 IEEE.

The Closing Wells as Heat Source

Directory of Open Access Journals (Sweden)

Gonet Andrzej

2004-09-01

Full Text Available The Turaszówka crude oil field is situated within the borders of Krosno town. The oil resources are nearly depleted. Many of the boreholes have already been liquidated. Currently, only 22 boreholes are being exploited. Eight of them are watered and exploiting oil along with the reservoir water.The boreholes were submitted for producing the geothermal energy, because of their location. They are situated within the urban area. The suggested solution allows for gaining the pure energy and also does not require additional expenditure for mining researches connected with closing of the abandoned boreholes of the field.The paper points to the suggestion and preliminary analysis for wells of Turaszówka oil field adaptation for borehole heat exchangers. There is also presentation of using the heat for Complex of Upper Grammar School heating system and the swimming pool which are both placed close to the oil field.

Review of lower hybrid wave heating and current drive

International Nuclear Information System (INIS)

Gormezano, C.

1986-01-01

Interaction of Lower Hybrid waves and plasmas is a very versatile method which has proven to be effective in a large range of applications: bulk ion heating, bulk electron heating, non inductive current drive. If the ratio between the mean velocity of HF induced fast particles and the thermal velocity of the bulk population is relatively small, effective bulk ion heating or bulk electron heating can occur via collisional transfer. If the above ratio is too large, fast ions, which have mainly a perpendicular energy, are poorly confined. Moreover they can be harmful for the discharge (impurities, etc...) since they are lost on the walls. In contrast, HF induced fast electrons gain essentially a parallel momentum from the wave. If unidirectional waves are launched, the dissymetry in electron distribution result in the obtention of an effective non inductive current

Active rc filter permits easy trade-off of amplifier gain and sensitivity to gain

Science.gov (United States)

Kerwin, W. J.; Shaffer, C. V.

1968-01-01

Passive RC network was designed with zeros of transmission in the right half of the complex frequency plane in the feedback loop of a simple negative-gain amplifier. The proper positioning provides any desired trade-off between amplifier gain and sensitivity to amplifier gain.

Potential of low-temperature nuclear heat applications

International Nuclear Information System (INIS)

1986-12-01

At present, more than one third of the fossil fuel currently used is being consumed to produce space heating and to meet industrial needs in many countries of the world. Imported oil still represents a large portion of this fossil fuel and despite its present relatively low price future market evolutions with consequent upward cost revisions cannot be excluded. Thus the displacement of the fossil fuel by cheaper low-temperature heat produced in nuclear power plants is a matter which deserves careful consideration. Technico-economic studies in many countries have shown that the use of nuclear heat is fully competitive with most of fossil-fuelled plants, the higher investment costs being offset by lower production cost. Another point in favour of heat generation by nuclear source is its indisputable advantage in terms of benefits to the environment. The IAEA activity plans for 1985-86 concentrate on information exchange with specific emphasis on the design criteria, operating experience, safety requirements and specifications of heat-only reactors, co-generation plants and existing power plants backfitted for additional heat applications. The information gained up to 1985 was discussed during the Advisory Group Meeting on the Potential of Low-Temperature Nuclear Heat Applications held in the Federal Institute for Reactor Research, Wuerenlingen, Switzerland in September 1985 and, is included in the present Technical Document

Air distribution and ventilation effectiveness in an occupied room heated by warm air

DEFF Research Database (Denmark)

Krajcik, Michal; Simone, Angela; Olesen, Bjarne W.

2012-01-01

and at different simulated outside conditions, internal heat gains and air change rates. Floor heating was also simulated and compared with the warm air heating system. Vertical air temperature profiles, air velocity profiles and equivalent temperatures were derived in order to describe the thermal environment...... floor heating system was simulated, the cooler ventilation air introduced to the room mixed well and created uniform conditions with a ventilation effectiveness of about 1.......Air distribution, ventilation effectiveness and thermal environment were experimentally studied in a simulated room in a low-energy building heated and ventilated by warm air supplied by a mixing ventilation system. Measurements were performed for various positions of the air terminal devices...

An output amplitude configurable wideband automatic gain control with high gain step accuracy

International Nuclear Information System (INIS)

He Xiaofeng; Ye Tianchun; Mo Taishan; Ma Chengyan

2012-01-01

An output amplitude configurable wideband automatic gain control (AGC) with high gain step accuracy for the GNSS receiver is presented. The amplitude of an AGC is configurable in order to cooperate with baseband chips to achieve interference suppression and be compatible with different full range ADCs. And what's more, the gain-boosting technology is introduced and the circuit is improved to increase the step accuracy. A zero, which is composed by the source feedback resistance and the source capacity, is introduced to compensate for the pole. The AGC is fabricated in a 0.18 μm CMOS process. The AGC shows a 62 dB gain control range by 1 dB each step with a gain error of less than 0.2 dB. The AGC provides 3 dB bandwidth larger than 80 MHz and the overall power consumption is less than 1.8 mA, and the die area is 800 × 300 μm 2 . (semiconductor integrated circuits)

The role of the velocity gradient in laminar convective heat transfer through a tube with a uniform wall heat flux

International Nuclear Information System (INIS)

Wang Liangbi; Zhang Qiang; Li Xiaoxia

2009-01-01

This paper aims to contribute to a better understanding of convective heat transfer. For this purpose, the reason why thermal diffusivity should be placed before the Laplacian operator of the heat flux, and the role of the velocity gradient in convective heat transfer are analysed. The background to these analyses is that, when the energy conservation equation of convective heat transfer is used to explain convective heat transfer there are two points that are difficult for teachers to explain and for undergraduates to understand: thermal diffusivity is placed before the Laplacian operator of temperature; on the wall surface (the fluid side) the velocity is zero, a diffusion equation of temperature is gained from energy conservation equation, however, temperature cannot be transported. Consequently, the real physical meaning of thermal diffusivity is not clearly reflected in the energy conservation equation, and whether heat transfer occurs through a diffusion process or a convection process on the wall surface is not clear. Through a simple convective heat transfer case: laminar convective heat transfer in a tube with a uniform wall heat flux on the tube wall, this paper explains these points more clearly. The results declare that it is easier for teachers to explain and for undergraduates to understand these points when a description of heat transfer in terms of the heat flux is used. In this description, thermal diffusivity is placed before the Laplacian operator of the heat flux; the role of the velocity gradient in convective heat transfer appears, on the wall surface, the fact whether heat transfer occurs through a diffusion process or a convection process can be explained and understood easily. The results are not only essential for teachers to improve the efficiency of university-level physics education regarding heat transfer, but they also enrich the theories for understanding heat transfer

Small reactors for low-temperature nuclear heat applications

International Nuclear Information System (INIS)

1988-06-01

In accordance with the Member States' calls for information exchange in the field of nuclear heat application (NHA) two IAEA meetings were organized already in 1976 and 1977. After this ''promising period'', the development of relevant programmes in IAEA Member States was slowed down and therefore only after several years interruption a new Technical Committee Meeting with a Workshop was organized in late 1983, to review the status of NHA, after a few new specific plans appeared in some IAEA Member States in the early 1980's for the use of heat from existing or constructed NPPs and for developing nuclear heating plants (NHP). In June 1987 an Advisory Group Meeting was convened in Winnipeg, Canada, to discuss and formulate a state-of-the-art review on ''Small Reactors for Low Temperature Nuclear Heat Application''. Information on this subject gained up to 1987 in the Member States whose experts attended this meeting is embodied in the present Technical Report. Figs and tabs

Development of a helium/helium intermediate heat exchanger with helical coil tube bundle

International Nuclear Information System (INIS)

Czimczik, A.; Hirschle, G.

1984-01-01

Besides the research and development work leading to the design basis for the reference heat exchanger, the stages of development up to the realisation of a nuclear He/He intermediate heat exchanger (IHX) include selected experiments in manufacturing techniques and with individual test components, as well as the design, fabrication and testing of representative prototype component. The process of manufacturing and experiences gained so far are described

Potential for solar space heating in Scotland

Energy Technology Data Exchange (ETDEWEB)

Macgregor, A W.K.

1980-07-01

This paper investigates the relative effectiveness of passive-type solar-assisted space heating systems at various latitudes within the British Isles. A comparison is made of the useful solar gain of the same system linked to the same house at four different locations. Month-by-month energy balances indicate that the annual useful solar contribution at the highest latitude (Lerwick, 60 deg N) is about 35% higher than at the lowest latitude (Kew, 53 deg N). The main reason for this difference is the higher heating loads in the north, particularly outside the winter months. The estimated available irradiation on south-facing vertical surfaces was almost the same at all four locations. Previous work in the UK indicates that, contrary to the conclusions in this paper, more southerly latitudes were the most favorable for solar space heating. The reasons for the disparity are discussed. It is recommended that research and development of passive solar-assisted space heating systems should be most vigorously pursued in the more northerly latitudes of the British Isles, where both the potential benefit and the need are greatest.

Correlation analysis of heat flux and fire behaviour and hazards of polycrystalline silicon photovoltaic panels

Science.gov (United States)

Ju, Xiaoyu; Zhou, Xiaodong; Peng, Fei; Wu, Zhibo; Lai, Dimeng; Hu, Yue; Yang, Lizhong

2017-05-01

This work aims to gain a better understanding of fire behaviour and hazards of PV panels under different radiation heat fluxes. The cone calorimeter tests were applied to simulate the situations when the front and back surfaces are exposed to heat flux in a fire, respectively. Through comparison of ignition time, mass loss rate and heat release rate, it is found that the back-up condition is more hazardous than face-up condition. Meanwhile, three key parameters: flashover propensity, total heat release and FED, were introduced to quantitatively illustrate fire hazards of a PV panel.

Gain attenuation of gated framing camera

International Nuclear Information System (INIS)

Xiao Shali; Liu Shenye; Cao Zhurong; Li Hang; Zhang Haiying; Yuan Zheng; Wang Liwei

2009-01-01

The theoretic model of framing camera's gain attenuation is analyzed. The exponential attenuation curve of the gain along the pulse propagation time is simulated. An experiment to measure the coefficient of gain attenuation based on the gain attenuation theory is designed. Experiment result shows that the gain follows an exponential attenuation rule with a quotient of 0.0249 nm -1 , the attenuation coefficient of the pulse is 0.00356 mm -1 . The loss of the pulse propagation along the MCP stripline is the leading reason of gain attenuation. But in the figure of a single stripline, the gain dose not follow the rule of exponential attenuation completely, instead, there is a gain increase at the stripline bottom. That is caused by the reflection of the pulse. The reflectance is about 24.2%. Combining the experiment and theory, which design of the stripline MCP can improved the gain attenuation. (authors)

Weight Gain during Pregnancy

Science.gov (United States)

... Global Map Premature Birth Report Cards Careers Archives Pregnancy Before or between pregnancies Nutrition, weight & fitness Prenatal ... fitness > Weight gain during pregnancy Weight gain during pregnancy E-mail to a friend Please fill in ...

The effect of intermittent lighting on metabolizable energy intake and heat production of male broilers.

Science.gov (United States)

Ohtani, S; Leeson, S

2000-02-01

Experiments were conducted to compare the effects of an intermittent lighting (IL) schedule with repeated cycles of 1 h light and 2 h darkness with a continuous lighting (CL) schedule on the performance, ME intake, and heat production of male broiler chickens. Body weight gain and feed intake were temporarily reduced after the changing from CL to IL; however, they were significantly higher in IL vs CL chickens during the subsequent period of 3 to 6 wk of age. The IL chickens exhibited a higher ME intake at 6 and 8 wk of age than did CL chickens. Total heat production in IL chickens was higher than for CL chickens, although heat production during the dark period was less than that during the light period for IL chickens. The higher feed intake observed in IL chickens appears to explain the superior body weight gain in IL broilers in simple terms.

Heat transfer in Rockwool modelling and method of measurement. Modelling radiative heat transfer in fibrous materials

Energy Technology Data Exchange (ETDEWEB)

Dyrboel, Susanne

1998-05-01

Fibrous materials are some of the most widely used materials for thermal insulation. In this project the focus of interest has been on fibrous materials for building application. Interest in improving the thermal properties of insulation materials is increasing as legislation is being tightened to reduce the overall energy consumption. A knowledge of the individual heat transfer mechanisms - whereby heat is transferred within a particular material is an essential tool to improve continuously the thermal properties of the material. Heat is transferred in fibrous materials by four different transfer mechanisms: conduction through air, conduction through fibres, thermal radiation and convection. In a particular temperature range the conduction through air can be regarded as a constant, and conduction through fibres is an insignificant part of the total heat transfer. Radiation, however, constitutes 25-40% of the total heat transfer in light fibrous materials. In Denmark and a number of other countries convection in fibrous materials is considered as non-existent when calculating heat transmission as well as when designing building structures. Two heat transfer mechanisms have been the focus of the current project: radiation heat transfer and convection. The radiation analysis serves to develop a model that can be used in further work to gain a wider knowledge of the way in which the morphology of the fibrous material, i.e. fibre diameter distribution, fibre orientation distribution etc., influences the radiation heat transfer under different conditions. The convection investigation serves to examine whether considering convection as non-existent is a fair assumption to use in present and future building structures. The assumption applied in practically is that convection makes a notable difference only in very thick insulation, at external temperatures below -20 deg. C, and at very low densities. For lager thickness dimensions the resulting heat transfer through the

Hybrid Ventilation with Innovative Heat Recovery—A System Analysis

Directory of Open Access Journals (Sweden)

Bengt Hellström

2013-02-01

Full Text Available One of the most important factors when low energy houses are built is to have good heat recovery on the ventilation system. However, standard ventilation units use a considerable amount of electricity. This article discusses the consequences on a system level of using hybrid ventilation with heat recovery. The simulation program TRNSYS was used in order to investigate a ventilation system with heat recovery. The system also includes a ground source storage and waste water heat recovery system. The result of the analysis shows that the annual energy gain from ground source storage is limited. However, this is partly a consequence of the fact that the well functioning hybrid ventilation system leaves little room for improvements. The analysis shows that the hybrid ventilation system has potential to be an attractive solution for low energy buildings with a very low need for electrical energy.

Effects of self-fields on electron trajectory and gain in two-stream electromagnetically pumped free-electron laser with ion channel guiding

International Nuclear Information System (INIS)

Saviz, S.; Ghorannevis, M.; Aghamir, Farzin M.; Mehdian, H.

2011-01-01

A theory for the two-stream free-electron laser with an electromagnetic wiggler (EMW) and an ion channel guiding is developed. In the analysis, the effects of self-fields have been taken into account. The electron trajectories and the small signal gain are derived. The stability of the trajectories, the characteristics of the linear gain and the normalized maximum gain are studied numerically. The dependence of the normalized frequency ω-circumflex corresponding to the maximum gain on the ion-channel frequency is presented. The results show that there are seven groups of orbits in the presence of the self-fields, which are similar to those reported in the absence of the self-fields. It is also shown that the normalized gains of 2 groups decrease while the rest increase with the increasing normalized ion-channel frequency. Furthermore, it is found that the two-stream instability and the self-field lead to a decrease in the maximum gain except for group 4. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

Critical heat flux analysis on change of plate temperature and cooling water flow rate for rectangular narrow gap with bilateral-heated cases

International Nuclear Information System (INIS)

M Hadi Kusuma; Mulya Juarsa; Anhar Riza Antariksawan

2013-01-01

Boiling heat transfer phenomena on rectangular narrow gap was related to the safety of nuclear reactors. Research done in order to study the safety of nuclear reactors in particular relating to boiling heat transfer and useful on the improvement of next-generation reactor designs. The research focused on calculation of the heat flux during the cooling process in rectangular narrow gap size 1.0 mm. with initial temperatures 200°C. 400°C, and 600°C, also the flow rates of cooling water 0,1 liters/second. 0,2 liters/second. and 0,3 liters/second. Experiments carried out by injecting water at a certain flow rate with the water temperature 85°C. Transient temperature measurement data recorded by the data acquisition system. Transient temperature measurement data is used to calculate the flux of heat gain is then used to obtain the heat transfer coefficient. This research aimed to obtain the correlation between critical heat flux and heat transfer coefficient to changes in temperatures and water flow rates for bilaterally-heated cases on rectangular narrow gap. The results obtained for a constant cooling water flow rate, critical heat flux will increase when hot plate temperature also increased. While on a constant hot plate temperature, coefficient heat transfer will increase when cooling water flow rate also increased. Thus it can be said that the cooling water flow rate and temperature of the hot plate has a significant effect on the critical heat flux and heat transfer coefficient resulted in quenching process of vertical rectangular narrow gap with double-heated cases. (author)

Errors in macromolecular synthesis after stress. A study of the possible protective role of the small heat shock proteinsBiochemistry

NARCIS (Netherlands)

Marin Vinader, L.

2006-01-01

The general goal of this thesis was to gain insight in what small heat shock proteins (sHsps) do with respect to macromolecular synthesis during a stressful situation in the cell. It is known that after a non-lethal heat shock, cells are better protected against a subsequent more severe heat shock,

The effect of location of a convective heat source on displacement ventilation: CFD study

Energy Technology Data Exchange (ETDEWEB)

Park, H.J.; Holland, D. [Dunham Associates, Inc., Minneapolis, MN (United States). Advanced Technologies Group

2001-08-01

Two-dimensional computational simulations are performed to examine the effect of vertical location of a convective heat source on thermal displacement ventilation systems. In this study, a heat source is modeled with seven different heights from the floor (0.5, 0.75, 1.0, 1.25, 1.5, 1.75, 2.0 m) in a displacement ventilation environment. The flow and temperature fields in thermal displacement ventilation systems vary depending on the location of the heat source. As the heat source rises, the convective heat gain from the heat source to an occupied zone becomes less significant. This effect changes the temperature field and results in the reduction of the cooling load in the occupied zone. The stratification level is also affected by the heat source location at a given flow rate. (author)

Risk Assessment of Heating, Ventilating, and Air-Conditioning Strategies in Low-Load Homes

Energy Technology Data Exchange (ETDEWEB)

Poerschke, Andrew [IBACOS, Inc., Pittsburgh, PA (United States)

2016-02-17

"Modern, energy efficient homes conforming to the Zero Energy Ready Home standard face the challenge of meeting high customer expectations for comfort. Traditional heating, ventilation, and air conditioning (HVAC) sizing and control strategies may be insufficient to adequately condition each zone due to unique load patterns in each room caused by a number of factors. These factors include solar heat gains, occupant-related gains, and gains associated with appliances and electronics. Because of shrinking shell loads, these intermittent factors are having an increasingly significant impact on the thermal load in each zone. Consequently, occupant comfort can be compromised. To evaluate the impact of climate and house geometry, as well as HVAC system and control strategies on comfort conditions, IBACOS analyzed the results of 99 TRNSYS multiple-zone simulations. The results of this analysis indicate that for simple-geometry and single-story plans, a single zone and thermostat can adequately condition the entire house. Demanding house geometry and houses with multiple stories require the consideration of multiple thermostats and multiple zones.

Principles of heat and mass transfer

CERN Document Server

Incropera, Frank P; Bergman, Theodore L; Lavine, Adrienne S

2013-01-01

Completely updated, the seventh edition provides engineers with an in-depth look at the key concepts in the field. It incorporates new discussions on emerging areas of heat transfer, discussing technologies that are related to nanotechnology, biomedical engineering and alternative energy. The example problems are also updated to better show how to apply the material. And as engineers follow the rigorous and systematic problem-solving methodology, they'll gain an appreciation for the richness and beauty of the discipline.

Leading Gainful Employment Metric Reporting

Science.gov (United States)

Powers, Kristina; MacPherson, Derek

2016-01-01

This chapter will address the importance of intercampus involvement in reporting of gainful employment student-level data that will be used in the calculation of gainful employment metrics by the U.S. Department of Education. The authors will discuss why building relationships within the institution is critical for effective gainful employment…

Waste Heat Recovery from a High Temperature Diesel Engine

Science.gov (United States)

Adler, Jonas E.

Government-mandated improvements in fuel economy and emissions from internal combustion engines (ICEs) are driving innovation in engine efficiency. Though incremental efficiency gains have been achieved, most combustion engines are still only 30-40% efficient at best, with most of the remaining fuel energy being rejected to the environment as waste heat through engine coolant and exhaust gases. Attempts have been made to harness this waste heat and use it to drive a Rankine cycle and produce additional work to improve efficiency. Research on waste heat recovery (WHR) demonstrates that it is possible to improve overall efficiency by converting wasted heat into usable work, but relative gains in overall efficiency are typically minimal ( 5-8%) and often do not justify the cost and space requirements of a WHR system. The primary limitation of the current state-of-the-art in WHR is the low temperature of the engine coolant ( 90 °C), which minimizes the WHR from a heat source that represents between 20% and 30% of the fuel energy. The current research proposes increasing the engine coolant temperature to improve the utilization of coolant waste heat as one possible path to achieving greater WHR system effectiveness. An experiment was performed to evaluate the effects of running a diesel engine at elevated coolant temperatures and to estimate the efficiency benefits. An energy balance was performed on a modified 3-cylinder diesel engine at six different coolant temperatures (90 °C, 100 °C, 125 °C, 150 °C, 175 °C, and 200 °C) to determine the change in quantity and quality of waste heat as the coolant temperature increased. The waste heat was measured using the flow rates and temperature differences of the coolant, engine oil, and exhaust flow streams into and out of the engine. Custom cooling and engine oil systems were fabricated to provide adequate adjustment to achieve target coolant and oil temperatures and large enough temperature differences across the

Can Beta Blockers Cause Weight Gain?

Science.gov (United States)

... cause weight gain? Can beta blockers cause weight gain? Answers from Sheldon G. Sheps, M.D. Yes. Weight gain can occur as a side effect of some ... and metoprolol (Lopressor, Toprol-XL). The average weight gain is about 2.6 pounds (about 1.2 ...

Floral temperature and optimal foraging: is heat a feasible floral reward for pollinators?

Directory of Open Access Journals (Sweden)

Sean A Rands

Full Text Available As well as nutritional rewards, some plants also reward ectothermic pollinators with warmth. Bumble bees have some control over their temperature, but have been shown to forage at warmer flowers when given a choice, suggesting that there is some advantage to them of foraging at warm flowers (such as reducing the energy required to raise their body to flight temperature before leaving the flower. We describe a model that considers how a heat reward affects the foraging behaviour in a thermogenic central-place forager (such as a bumble bee. We show that although the pollinator should spend a longer time on individual flowers if they are warm, the increase in total visit time is likely to be small. The pollinator's net rate of energy gain will be increased by landing on warmer flowers. Therefore, if a plant provides a heat reward, it could reduce the amount of nectar it produces, whilst still providing its pollinator with the same net rate of gain. We suggest how heat rewards may link with plant life history strategies.

Fifteen years of heating enterprise in southern Finland; Laempoeyrittaejyyttae Uudellamaalla jo 15 vuotta

Energy Technology Data Exchange (ETDEWEB)

Vuorio, K.; Lahdensaari-Natt, L., Email: kari.vuorio@tts.fi, Email: liisa.lahdensaari@tts.fi

2013-06-01

Heating entrepreneurs produce heat locally and sell heat to the end user at an agreed price. Heat is usually produced by burning wood chips from the companys own forests or from the surrounding forests. There were more than 500 heating plants run by heating entrepreneurs in Finland in the beginning of 2012. Some thirty of them were situated in the area of Uusimaa in southern Finland. It seems that heating entrepreneurship is steadily gaining ground, since the amount of heating plants has increased annually by around twenty. TTS-Tyoetehoseura (Work Efficiency Institute) started the nationwide research and development of heating entrepreneurship in 1993. At that time there were only three heating companies in Finland. The first started to operate in Uusimaa during 1994-1998. Among the first heating plants to be built in 1998 were Perttula Vocational School (KEUDA) with 500 kiloWatts capacity in Nurmijaervi, Ohkola school with 200 kiloWatts capacity in Maentsaelae and the Vaestankvarn schoolfarm with 700 kiloWatts capacity in Inkoo, of which we will give more info about in this bulletin. (orig.)

Estimating the potential gains from mergers

DEFF Research Database (Denmark)

Bogetoft, Peter; Wang, Dexiang

2005-01-01

We introduce simple production economic models to estimate the potential gains from mergers. We decompose the gains into technical ef¿ciency, size (scale) and harmony (mix) gains, and we discuss alternative ways to capture these gains. We propose to approximate the production processes using...... the non-parametric. Data Envelopment Analysis (DEA) approach, and we use the resulting operational approach to estimate the potential gains from merging agricultural extension of¿ces in Denmark....

An analysis of electro-osmotic and magnetohydrodynamic heat pipes

International Nuclear Information System (INIS)

Harrison, M.A.

1988-01-01

Mechanically simple methods of improving heat transport in heat pipes are investigated. These methods are electro-osmotic and magnetohydrodynamic augmentation. For the electro-osmotic case, a detailed electrokinetic model is used. The electrokinetic model used includes the effects of pore surface curvature and multiple ion diffusivities. The electrokinetic model is extended to approximate the effects of elevated temperature. When the electro-osmotic model is combined with a suitable heat-pipe model, it is found that the electro-osmotic pump should be a thin membrane. Arguments are provided that support the use of a volatile electrolyte. For the magnetohydrodynamic case, a brief investigation is provided. A quasi-one-dimensional hydromagnetic duct flow model is used. This hydromagnetic model is extended to approximate flow effects unique to heat pipes. When combined with a suitable heat pipe model, it is found that there is no performance gain for the case considered. In fact, there are serious pressure-distribution problems that have not been previously recognized. Potential solutions to these pressure-distribution problems are suggested

Fabrication experiments for large helix heat exchangers

International Nuclear Information System (INIS)

Burgsmueller, P.

1978-01-01

The helical tube has gained increasing attention as a heat transfer element for various kinds of heat exchangers over the last decade. Regardless of reactor type and heat transport medium, nuclear steam generators of the helix type are now in operation, installlation, fabrication or in the project phase. As a rule, projects are based on the extrapolation of existing technologies. In the particlular case of steam generators for HTGR power stations, however, existing experience is with steam generators of up to about 2 m diameter whereas several projects involve units more than twice as large. For this reason it was felt that a fabrication experiment was necessary in order to verify the feasibility of modern steam generator designs. A test rig was erected in the SULZER steam generator shops at Mantes, France, and skilled personnel and conventional production tools were employed in conducting experiments relating to the coiling, handling and threading of large helices. (Auth.)

Analysis of Decentralized Control for Absorption Cycle Heat Pumps

DEFF Research Database (Denmark)

Vinther, Kasper; Just Nielsen, Rene; Nielsen, Kirsten Mølgaard

2015-01-01

Email Print Request Permissions This paper investigates decentralized control structures for absorption cycle heat pumps and a dynamic nonlinear model of a single-effect LiBr-water absorption system is used as case study. The model has four controllable inputs, which can be used to stabilize...... the operation of the heat pump under different load conditions. Different feasible input-output pairings are analyzed by computation of relative gain array matrices and scaled condition numbers, which indicate the best pairing choice and the potential of each input-output set. Further, it is possible...... to minimize the effect of cross couplings and improve stability with the right pairing of input and output. Simulation of selected candidate input-output pairings demonstrate that decentralized control can provide stable operation of the heat pump....

A Comparative Cycle and Refrigerant Simulation Procedure Applied on Air-Water Heat Pumps

DEFF Research Database (Denmark)

Mader, Gunda; Palm, Björn; Elmegaard, Brian

2012-01-01

A vapor compression heat pump absorbs heat from the environment at a low temperature level and rejects heat at a high temperature level. The bigger the difference between the two temperature levels the more challenging is it to gain high energy efficiency with a basic cycle layout as found in most...... small capacity heat pump applications today. Many of the applicable refrigerants also reach their technical limits regarding low vapor pressure for very low source temperatures and high discharge temperatures for high sink temperatures. These issues are especially manifest for air-water heat pumps. Many...... alternative cycle setups and refrigerants are known to improve the energy efficiency of a vapor compression cycle and reduce discharge temperatures. However not all of them are feasible for small capacity heat pumps from a cost and complexity point of view. This paper presents a novel numerical approach...

Patterns of Seasonal Heat Uptake and Release Over the Arctic Ocean Between 1979-2016

Science.gov (United States)

Helmberger, M. N.; Serreze, M. C.

2017-12-01

As the Arctic Ocean loses its sea ice cover, there is a stronger oceanic heat gain from the surface fluxes throughout the spring and summer; ultimately meaning that there is more energy to transfer out of the ocean to the atmosphere and outer space in the autumn and winter. Recent work has shown that the increased oceanic heat content at the end of summer in turn delays autumn ice growth, with implications for marine shipping and other economic activities. Some of the autumn and winter heat loss to the atmosphere is represented by evaporation, which increases the atmospheric water vapor content, and there is growing evidence that this is contributing to increases in regional precipitation. However, depending on patterns of seasonal sea ice retreat and weather conditions, the spring-summer heat uptake and autumn-winter heat loss can be highly variable from year to year and regionally. Here, we examine how the seasonality in upper ocean heat uptake and release has evolved over the past 37 years and the relationships between this seasonal heat gain and loss and the evolution of sea ice cover. We determine which regions have seen the largest increases in total seasonal heat uptake and how variable this uptake can be. Has the timing at which the Arctic Ocean (either as a whole or by region) transitions from an atmospheric energy sink to an atmospheric energy source (or from a source to a sink) appreciably changed? What changes have been observed in the seasonal rates of seasonal heat uptake and release? To begin answering these questions, use is made of surface fluxes from the ERA-Interim reanalysis and satellite-derived sea ice extent spanning the period 1979 through the present. Results from ERA-Interim will be compared to those from other reanalyses and satellite-derived flux estimates.

Recent trends and developments in infrared heating in food processing.

Science.gov (United States)

Rastogi, Navin K

2012-01-01

Fruit processing and preservation technologies must keep fresh-like characteristics while providing an acceptable and convenient shelf life as well as assuring safety and nutritional value. Processing technologies include a wide range of methodologies to inactivate microorganisms, improve quality and stability, and preserve and minimize changes of fruit fresh-like characteristics. Infrared (IR) heating offers many advantages over conventional heating under similar conditions, which include reduced heating time, uniform heating, reduced quality losses, versatile, simple and compact equipment, and significant energy saving. The integration of IR with other matured processing operations such as blanching, dehydration, freeze-dehydration, thawing, roasting, baking, cooking has been shown to open up new processing options. Combinations of IR heating with microwave heating and other common conductive and convective modes of heating have been gaining momentum because of increased energy throughput. A number of publications and patents have demonstrated novel and diverse uses of this technology. This review aims at identifying the opportunities and challenges associated with this technology. The effect of IR on food quality attributes is also discussed. The types of equipment commonly used for IR processing have also been summarized.

Influence of different technologies on dynamic pricing in district heating systems: Comparative case studies

DEFF Research Database (Denmark)

Dominkovic, Dominik Franjo; Wahlroos, Mikko; Syri, Sanna

2018-01-01

District heating markets are often dominated by monopolies in both Denmark and Finland. The same companies, often owned by local municipalities, are usually operating both supplying plants and district heating networks, while the pricing mechanisms are rigid, often agreed upon for one year...... in advance. The mentioned ownership scheme may cause problems, when one tries to gain a third party access in order to deliver excess heat or heat from cheaper heating plants. In this paper, two case studies were carried out to simulate the district heating systems based on dynamic pricing. Case studies were...... carried out for Sønderborg, Denmark and Espoo, Finland. The results showed that dynamic pricing fosters feeding the waste heat into the grid, as dynamic pricing reduced the total primary energy consumption and CO2 emissions in both case studies. In the best scenarios, the weighted average heat price...

Monitoring of a heat pump to energy recovery and process temperature control

Energy Technology Data Exchange (ETDEWEB)

Kaneps, M

1986-03-01

This reports on the development and implementation of a heat pump monitoring program detailing the application and adaptation of standard commercial heat pump equipment for the extraction and use of themal energy from ocean source seawater along Canada's Atlantic Coast. The specific application was a lobster holding facility owned by Clearwater Lobsters Limited of Halifax, Nova Scotia. Examination of the daata indicated the heat pump system could extract and use thermal energy at or near initial design conditions. The lobsters were able to be held at consistently lower temperatures which improved product quality and reduced shrinkage. Influx of seawater debris, marine growth, and dryland pound heat gain were indentified as the only major problems. The information gathered from the monitoring study indicated that heat pump systems can be adapted to extract and utilize thermal energy from ocean source seawater. 50 figs., 123 tabs.

A gain-coefficient switched Alexandrite laser

International Nuclear Information System (INIS)

Lee, Chris J; Van der Slot, Peter J M; Boller, Klaus-J

2013-01-01

We report on a gain-coefficient switched Alexandrite laser. An electro-optic modulator is used to switch between high and low gain states by making use of the polarization dependent gain of Alexandrite. In gain-coefficient switched mode, the laser produces 85 ns pulses with a pulse energy of 240 mJ at a repetition rate of 5 Hz.

Methodology used to calculate moderator-system heat load at full power and during reactor transients in CANDU reactors

International Nuclear Information System (INIS)

Aydogdu, K.

1998-01-01

Nine components determine the moderator-system heat load during full-power operation and during a reactor power transient in a CANDU reactor. The components that contribute to the total moderator-system heat load at any time consist of the heat generated in the calandria tubes, guide tubes and reactivity mechanisms, moderator and reflector; the heat transferred from calandria shell, the inner tubesheets and the fuel channels; and the heat gained from moderator pumps and heat lost from piping. The contributions from each of these components will vary with time during a reactor transient. The sources of heat that arise from the deposition of nuclear energy can be divided into two categories, viz., a) the neutronic component (which is directly proportional to neutronic power), which includes neutron energy absorption, prompt-fission gamma absorption and capture gamma absorption; and b) the fission-product decay-gamma component, which also varies with time after initiation of the transient. An equation was derived to calculate transient heat loads to the moderator. The equation includes two independent variables that are the neutronic power and fission-product decay-gamma power fractions during the transient and a constant term that represents the heat gained from moderator pumps and heat lost from piping. The calculated heat load in the moderator during steady-state full-power operation for a CANDU 6 reactor was compared with available measurements from the Point Lepreau, Wolsong 1 and Gentilly-2 nuclear generating stations. The calculated and measured values were in reasonably good agreement. (author)

Efficiency gain of solid oxide fuel cell systems by using anode offgas recycle - Results for a small scale propane driven unit

Science.gov (United States)

Dietrich, Ralph-Uwe; Oelze, Jana; Lindermeir, Andreas; Spitta, Christian; Steffen, Michael; Küster, Torben; Chen, Shaofei; Schlitzberger, Christian; Leithner, Reinhard

The transfer of high electrical efficiencies of solid oxide fuel cells (SOFC) into praxis requires appropriate system concepts. One option is the anode-offgas recycling (AOGR) approach, which is based on the integration of waste heat using the principle of a chemical heat pump. The AOGR concept allows a combined steam- and dry-reforming of hydrocarbon fuel using the fuel cell products steam and carbon dioxide. SOFC fuel gas of higher quantity and quality results. In combination with internal reuse of waste heat the system efficiency increases compared to the usual path of partial oxidation (POX). The demonstration of the AOGR concept with a 300 Wel-SOFC stack running on propane required: a combined reformer/burner-reactor operating in POX (start-up) and AOGR modus; a hotgas-injector for anode-offgas recycling to the reformer; a dynamic process model; a multi-variable process controller; full system operation for experimental proof of the efficiency gain. Experimental results proof an efficiency gain of 18 percentage points (η·POX = 23%, η·AOGR = 41%) under idealized lab conditions. Nevertheless, further improvements of injector performance, stack fuel utilization and additional reduction of reformer reformer O/C ratio and system pressure drop are required to bring this approach into self-sustaining operation.

Optimal Management of Geothermal Heat Extraction

Science.gov (United States)

Patel, I. H.; Bielicki, J. M.; Buscheck, T. A.

2015-12-01

Geothermal energy technologies use the constant heat flux from the subsurface in order to produce heat or electricity for societal use. As such, a geothermal energy system is not inherently variable, like systems based on wind and solar resources, and an operator can conceivably control the rate at which heat is extracted and used directly, or converted into a commodity that is used. Although geothermal heat is a renewable resource, this heat can be depleted over time if the rate of heat extraction exceeds the natural rate of renewal (Rybach, 2003). For heat extraction used for commodities that are sold on the market, sustainability entails balancing the rate at which the reservoir renews with the rate at which heat is extracted and converted into profit, on a net present value basis. We present a model that couples natural resource economic approaches for managing renewable resources with simulations of geothermal reservoir performance in order to develop an optimal heat mining strategy that balances economic gain with the performance and renewability of the reservoir. Similar optimal control approaches have been extensively studied for renewable natural resource management of fisheries and forests (Bonfil, 2005; Gordon, 1954; Weitzman, 2003). Those models determine an optimal path of extraction of fish or timber, by balancing the regeneration of stocks of fish or timber that are not harvested with the profit from the sale of the fish or timber that is harvested. Our model balances the regeneration of reservoir temperature with the net proceeds from extracting heat and converting it to electricity that is sold to consumers. We used the Non-isothermal Unconfined-confined Flow and Transport (NUFT) model (Hao, Sun, & Nitao, 2011) to simulate the performance of a sedimentary geothermal reservoir under a variety of geologic and operational situations. The results of NUFT are incorporated into the natural resource economics model to determine production strategies that

Study of gain-coupled distributed feedback laser based on high order surface gain-coupled gratings

Science.gov (United States)

Gao, Feng; Qin, Li; Chen, Yongyi; Jia, Peng; Chen, Chao; Cheng, LiWen; Chen, Hong; Liang, Lei; Zeng, Yugang; Zhang, Xing; Wu, Hao; Ning, Yongqiang; Wang, Lijun

2018-03-01

Single-longitudinal-mode, gain-coupled distributed feedback (DFB) lasers based on high order surface gain-coupled gratings are achieved. Periodic surface metal p-contacts with insulated grooves realize gain-coupled mechanism. To enhance gain contrast in the quantum wells without the introduction of effective index-coupled effect, groove length and depth were well designed. Our devices provided a single longitudinal mode with the maximum CW output power up to 48.8 mW/facet at 971.31 nm at 250 mA without facet coating, 3dB linewidth (39 dB). Optical bistable characteristic was observed with a threshold current difference. Experimentally, devices with different cavity lengths were contrasted on power-current and spectrum characteristics. Due to easy fabrication technique and stable performance, it provides a method of fabricating practical gain-coupled distributed feedback lasers for commercial applications.

Analysis of the efficiency of a hybrid foil tunnel heating system

Science.gov (United States)

Kurpaska, Sławomir; Pedryc, Norbert

2017-10-01

The paper analyzes the efficiency of the hybrid system used to heat the foil tunnel. The tested system was built on the basis of heat gain in a cascade manner. The first step is to heat the water in the storage tank using the solar collectors. The second stage is the use of a heat pump (HP) in order to heat the diaphragm exchangers. The lower HP heat source is a cascade first stage buffer. In the storage tank, diaphragm exchangers used for solar collectors and heat pumps are installed. The research was carried out at a research station located in the University of Agriculture in Cracow. The aim was to perform an analysis of the efficiency of a hybrid system for the heating of a foil tunnel in the months from May to September. The efficiency of the entire hybrid system was calculated as the relation of the effect obtained in reference to the electrical power used to drive the heat pump components (compressor drive, circulation pump), circulation pumps and fans installed in the diaphragm heaters. The resulting effect was the amount of heat supplied to the interior of the object as a result of the internal air being forced through the diaphragm exchangers.

Cylinder pressure, performance parameters, heat release, specific heats ratio and duration of combustion for spark ignition engine

Energy Technology Data Exchange (ETDEWEB)

Shehata, M.S. [Mechanical Engineering Technology Department, Higher Institute of Technology, Banha University, 4Zagalol Street, Benha, Galubia 1235 Z (Egypt)

2010-12-15

An experimental work were conducted for investigating cylinder pressure, performance parameters, heat release, specific heat ratio and duration of combustion for multi cylinder spark ignition engine (SIE). Ccylinder pressure was measured for gasoline, kerosene and Liquefied Petroleum Gases (LPG) separately as a fuel for SIE. Fast Fourier Transformations (FFT) was used to cylinder pressure data transform from time domain into frequency domain to develop empirical correlation for calculating cylinder pressures at different engine speeds and different fuels. In addition, Inverse Fast Fourier Transformations (IFFT) was used to cylinder pressure reconstruct into time domain. The results gave good agreement between the measured cylinder pressure and the reconstructed cylinder pressure in time domain with different engine speeds and different fuels. The measured cylinder pressure and hydraulic dynamotor were the source of data for calculating engine performance parameters. First law of thermodynamics and single zone heat release model with temperature dependant specific heat ratio {gamma}(T) were the main tools for calculating heat release and heat transfer to cylinder walls. Third order empirical correlation for calculating {gamma}(T) was one of the main gains of the present study. The correlation gave good agreement with other researchers with wide temperatures range. For kerosene, cylinder pressure is higher than for gasoline and LPG due to high volumetric efficiency where kerosene density (mass/volume ratio) is higher than gasoline and LPG. In addition, kerosene heating value is higher than gasoline that contributes in heat release rate and pressure increases. Duration of combustion for different engine speeds was determined using four different methods: (I) Mass fuel burnt, (II) Entropy change, (III) Temperature dependant specific heat ratio {gamma}(T), and (IV) Logarithmic scale of (P and V). The duration of combustion for kerosene is smaller than for gasoline and

Cylinder pressure, performance parameters, heat release, specific heats ratio and duration of combustion for spark ignition engine

International Nuclear Information System (INIS)

Shehata, M.S.

2010-01-01

An experimental work were conducted for investigating cylinder pressure, performance parameters, heat release, specific heat ratio and duration of combustion for multi cylinder spark ignition engine (SIE). Ccylinder pressure was measured for gasoline, kerosene and Liquefied Petroleum Gases (LPG) separately as a fuel for SIE. Fast Fourier Transformations (FFT) was used to cylinder pressure data transform from time domain into frequency domain to develop empirical correlation for calculating cylinder pressures at different engine speeds and different fuels. In addition, Inverse Fast Fourier Transformations (IFFT) was used to cylinder pressure reconstruct into time domain. The results gave good agreement between the measured cylinder pressure and the reconstructed cylinder pressure in time domain with different engine speeds and different fuels. The measured cylinder pressure and hydraulic dynamotor were the sours of data for calculating engine performance parameters. First law of thermodynamics and single zone heat release model with temperature dependant specific heat ratio γ(T) were the main tools for calculating heat release and heat transfer to cylinder walls. Third order empirical correlation for calculating γ(T) was one of the main gains of the present study. The correlation gave good agreement with other researchers with wide temperatures range. For kerosene, cylinder pressure is higher than for gasoline and LPG due to high volumetric efficiency where kerosene density (mass/volume ratio) is higher than gasoline and LPG. In addition, kerosene heating value is higher than gasoline that contributes in heat release rate and pressure increases. Duration of combustion for different engine speeds was determined using four different methods: (I) Mass fuel burnt, (II) Entropy change, (III) Temperature dependant specific heat ratio γ(T), and (IV) Logarithmic scale of (P and V). The duration of combustion for kerosene is smaller than for gasoline and LPG due to high

Weight gain following treatment of hyperthyroidism.

Science.gov (United States)

Dale, J; Daykin, J; Holder, R; Sheppard, M C; Franklyn, J A

2001-08-01

Patients frequently express concern that treating hyperthyroidism will lead to excessive weight gain. This study aimed to determine the extent of, and risk factors for, weight gain in an unselected group of hyperthyroid patients. We investigated 162 consecutive hyperthyroid patients followed for at least 6 months. Height, weight, clinical features, biochemistry and management were recorded at each clinic visit. Documented weight gain was 5.42 +/- 0.46 kg (mean +/- SE) and increase in BMI was 8.49 +/- 0.71%, over a mean 24.2 +/- 1.6 months. Pre-existing obesity, Graves' disease causing hyperthyroidism, weight loss before presentation and length of follow-up each independently predicted weight gain. Patients treated with thionamides or radioiodine gained a similar amount of weight (thionamides, n = 87, 5.16 +/- 0.63 kg vs. radioiodine, n = 62, 4.75 +/- 0.57 kg, P = 0.645), but patients who underwent thyroidectomy (n = 13) gained more weight (10.27 +/- 2.56 kg vs. others, P = 0.007). Development of hypothyroidism (even transiently) was associated with weight gain (never hypothyroid, n = 102, 4.57 +/- 0.52 kg, transiently hypothyroid, n = 29, 5.37 +/- 0.85 kg, on T4, n = 31, 8.06 +/- 1.42 kg, P = 0.014). This difference remained after correcting for length of follow-up. In the whole cohort, weight increased by 3.95 +/- 0.40 kg at 1 year (n = 144) to 9.91 +/- 1.62 kg after 4 years (n = 27) (P = 0.008), representing a mean weight gain of 3.66 +/- 0.44 kg/year. We have demonstrated marked weight gain after treatment of hyperthyroidism. Pre-existing obesity, a diagnosis of Graves' disease and prior weight loss independently predicted weight gain and weight continued to rise with time. Patients who became hypothyroid, despite T4 replacement, gained most weight.

Gain control mechanisms in spinal motoneurons

Directory of Open Access Journals (Sweden)

Michael David Johnson

2014-07-01

Full Text Available Motoneurons provide the only conduit for motor commands to reach muscles. For many years, motoneurons were in fact considered to be little more than passive wires. Systematic studies in the past 25 years however have clearly demonstrated that the intrinsic electrical properties of motoneurons are under strong neuromodulatory control via multiple sources. The discovery of potent neuromodulation from the brainstem and its ability to change the gain of motoneurons shows that the passive view of the motor output stage is no longer tenable. A mechanism for gain control at the motor output stage makes good functional sense considering our capability of generating an enormous range of forces, from very delicate (e.g. putting in a contact lens to highly forceful (emergency reactions. Just as sensory systems need gain control to deal with a wide dynamic range of inputs, so to might motor output need gain control to deal with the wide dynamic range of the normal movement repertoire. Two problems emerge from the potential use of the brainstem monoaminergic projection to motoneurons for gain control. First, the projection is highly diffuse anatomically, so that independent control of the gains of different motor pools is not feasible. In fact, the system is so diffuse that gain for all the motor pools in a limb likely increases in concert. Second, if there is a system that increases gain, probably a system to reduce gain is also needed. In this review, we summarize recent studies that show local inhibitory circuits within the spinal cord, especially reciprocal and recurrent inhibition, have the potential to solve both of these problems as well as constitute another source of gain modulation.

Receiver Gain Modulation Circuit

Science.gov (United States)

Jones, Hollis; Racette, Paul; Walker, David; Gu, Dazhen

2011-01-01

A receiver gain modulation circuit (RGMC) was developed that modulates the power gain of the output of a radiometer receiver with a test signal. As the radiometer receiver switches between calibration noise references, the test signal is mixed with the calibrated noise and thus produces an ensemble set of measurements from which ensemble statistical analysis can be used to extract statistical information about the test signal. The RGMC is an enabling technology of the ensemble detector. As a key component for achieving ensemble detection and analysis, the RGMC has broad aeronautical and space applications. The RGMC can be used to test and develop new calibration algorithms, for example, to detect gain anomalies, and/or correct for slow drifts that affect climate-quality measurements over an accelerated time scale. A generalized approach to analyzing radiometer system designs yields a mathematical treatment of noise reference measurements in calibration algorithms. By treating the measurements from the different noise references as ensemble samples of the receiver state, i.e. receiver gain, a quantitative description of the non-stationary properties of the underlying receiver fluctuations can be derived. Excellent agreement has been obtained between model calculations and radiometric measurements. The mathematical formulation is equivalent to modulating the gain of a stable receiver with an externally generated signal and is the basis for ensemble detection and analysis (EDA). The concept of generating ensemble data sets using an ensemble detector is similar to the ensemble data sets generated as part of ensemble empirical mode decomposition (EEMD) with exception of a key distinguishing factor. EEMD adds noise to the signal under study whereas EDA mixes the signal with calibrated noise. It is mixing with calibrated noise that permits the measurement of temporal-functional variability of uncertainty in the underlying process. The RGMC permits the evaluation of EDA by

Vasculature of the hive: heat dissipation in the honey bee ( Apis mellifera) hive

Science.gov (United States)

Bonoan, Rachael E.; Goldman, Rhyan R.; Wong, Peter Y.; Starks, Philip T.

2014-06-01

Eusocial insects are distinguished by their elaborate cooperative behavior and are sometimes defined as superorganisms. As a nest-bound superorganism, individuals work together to maintain favorable nest conditions. Residing in temperate environments, honey bees ( Apis mellifera) work especially hard to maintain brood comb temperature between 32 and 36 °C. Heat shielding is a social homeostatic mechanism employed to combat local heat stress. Workers press the ventral side of their bodies against heated surfaces, absorb heat, and thus protect developing brood. While the absorption of heat has been characterized, the dissipation of absorbed heat has not. Our study characterized both how effectively worker bees absorb heat during heat shielding, and where worker bees dissipate absorbed heat. Hives were experimentally heated for 15 min during which internal temperatures and heat shielder counts were taken. Once the heat source was removed, hives were photographed with a thermal imaging camera for 15 min. Thermal images allowed for spatial tracking of heat flow as cooling occurred. Data indicate that honey bee workers collectively minimize heat gain during heating and accelerate heat loss during cooling. Thermal images show that heated areas temporarily increase in size in all directions and then rapidly decrease to safe levels (<37 °C). As such, heat shielding is reminiscent of bioheat removal via the cardiovascular system of mammals.

Usage of Heat Pump Dryer in Food Drying Process and Apple Drying Application

Directory of Open Access Journals (Sweden)

Gökhan Gürlek

2015-12-01

Full Text Available In Turkey, drying is achieved natural method by spreading out the material on the ground. In this way, there are many disadvantages like low quality and hygienic problems. The resulting loss of food quality in the dried products may have effect negatively trade potential and economical worth. For preventing the deterioration of the materials different types of drying methods have been developed. Low energy consumption applications are important for drying industry besides high product quality. For this purpose, heat pump dryer is gaining importance day by day in drying applications. In this study, the working principle of the heat pump dryer, heat pump types in the drying process and the heat pump dryer performance criteria will be considered. An example of application will be described using obtained results from apple drying operation that is conducted in the heat pump dryer.

Pulse heating and ignition for off-centre ignited targets

International Nuclear Information System (INIS)

Mahdy, A.I.; Takabe, H.; Mima, K.

1999-01-01

An off-centre ignition model has been used to study the ignition conditions for laser targets related to the fast ignition scheme. A 2-D hydrodynamic code has been used, including alpha particle heating. The main goal of the study is the possibility of obtaining a high gain ICF target with fast ignition. In order to determine the ignition conditions, samples with various compressed core densities having different spark density-radius product (i.e. areal density) values were selected. The study was carried out in the presence of an external heating source, with a constant heating rate. A dependence of the ignition conditions on the heating rate of the external pulse is demonstrated. For a given set of ignition conditions, our simulation showed that an 11 ps pulse with 17 kJ of injected energy into the spark area was required to achieve ignition for a compressed core with a density of 200 g/cm 3 and 0.5 g/cm 2 spark areal density. It is shown that the ignition conditions are highly dependent on the heating rate of the external pulse. (author)

Recent research and development of intermediate heat exchanger for VHTR plant

Energy Technology Data Exchange (ETDEWEB)

Shimizu, Akira; Matsumura, Noboru; Nishikawa, Hidetsugu; Yamada, Seiya [Nagasaki Shipyard and Engine Works, Mitsubishi Heavy Industries, Ltd., Nagasaki (Japan)

1984-07-01

This paper describes recent tests which show progress in design of Intermediate Heat Exchanger (IHX) for high-temperature gas cooled reactor plants developed for process heat application utilizing nuclear thermal energy. As the IHX must have a large heat exchanging capacity, the most important consideration is to design a compact heat exchanger having high efficiency. For the improvement of heat transfer characteristics, tests were performed at Mitsubishi Heavy Industries such as, trial manufacturing, heat transfer characteristic tests and nondestructive inspection tests of finned tubes. Results are as follows; (1) Finned tubes produced by rolling were able to be wound helically by bending machine. (2) Laboratory tests showed this tube had good heat transfer characteristics. (3) There was not much difference between finned tubes and bare tubes for detection of defects by the eddy current tests. (4) A trial assembly using the same scale model showed that the present design is easy to assemble. (5) Automatic orbital welding can be adopted for the welding between tube and tube sheet. As the result of the experiences gained from these successful tests, the design of the IHX has been greatly improved. (author)

Experience gained in France on heat recovery from nuclear plant for agriculture and pisciculture

International Nuclear Information System (INIS)

Balligand, P.; Dumont, M.; Grauby, A.; Le Gouellec, P.

1977-01-01

For just five years the Commissariat a l'Energie Atomique has been interested in the use of thermal wastes from industrial installations particularly from nuclear power plants. Different types of pilot hothouses and their heating with water are presented in detail. The conclusions are that the thermal power plants owing to the Carnot principle release up to 60% of the thermal energy produced in the boiler into the environment but this thermal energy is at a very low temperature. In this paper it has been shown that agriculture and pisciculture can be satisfied with those low temperature waters. But transportation of this low temperature water is quite expensive and the total economy of a project has to be very carefully examined. (M.S.)

Optimal weight gain in triplet pregnancies.

Science.gov (United States)

Johnston, Robert C; Erfani, Hadi; Shamshirsaz, Amir A; Spiel, Melissa; Ravangard, Sam F; Shaman, Majid; Allaf, M Baraa; Shamshirsaz, Alireza A; Haeri, Sina

2017-08-01

To identify appropriate weight gain in triplet gestations, which may aid in reducing the risk of perinatal morbidity within this high-risk cohort. This retrospective cohort study evaluated all non-anomalous triplet pregnancies between 23 and 40 weeks' gestation resulting in live births at five tertiary-care medical centers between 1991 and 2011. Subjects were divided by pre-pregnancy BMI into underweight, normal-weight, overweight, and obese groups, and then stratified by low (gain (≥1.5 lbs/week). Primary outcomes included spontaneous preterm birth and preeclampsia. We included 116 mothers and 348 corresponding neonates for final analysis. The incidence of preeclampsia and preterm delivery less than 32 weeks' gestation was 37% and 41%, respectively. The incidence of preeclampsia increased with weight gain per week, but was not statistically different from subjects who gained less weight. We found no statistical correlation between weight gain per week and preterm delivery. We found no association between preeclampsia or preterm delivery and increasing weight gain in triplet pregnancies. The association with increased risk for preeclampsia was predominantly due to BMI effect. Based on the current study, recommendations for optimal weight gain in mothers with triplet gestations could not be defined.

Passive decay heat removal from the core region

International Nuclear Information System (INIS)

Hichen, E.F.; Jaegers, H.

2002-01-01

The decay heat in commercial Light Water Reactors is commonly removed by active and redundant safety systems supported by emergency power. For advanced power plant designs passive safety systems using a natural circulation mode are proposed: several designs are discussed. New experimental data gained with the NOKO and PANDA facilities as well as operational data from the Dodewaard Nuclear Power Plant are presented and compared with new calculations by different codes. In summary, the effectiveness of these passive decay heat removal systems have been demonstrated: original geometries and materials and for the NOKO facility and the Dodewaard Reactor typical thermal-hydraulic inlet and boundary conditions have been used. With several codes a good agreement between calculations and experimental data was achieved. (author)

Analyzing Design Heating Loads in Superinsulated Buildings

Energy Technology Data Exchange (ETDEWEB)

Arena, Lois [Consortium for Advanced Residential Buildings, Norwalk, CT (United States)

2015-06-16

The U.S. Department of Energy’s Building America research team Consortium for Advanced Residential Buildings (CARB) worked with the EcoVillage cohousing community in Ithaca, New York, on the Third Residential EcoVillage Experience neighborhood. This communityscale project consists of 40 housing units—15 apartments and 25 single-family residences. Units range in size from 450 ft2 to 1,664 ft2 and cost from $80,000 for a studio apartment to $235,000 for a three- or four-bedroom single-family home. For the research component of this project, CARB analyzed current heating system sizing methods for superinsulated homes in cold climates to determine if changes in building load calculation methodology should be recommended. Actual heating energy use was monitored and compared to results from the Air Conditioning Contractors of America’s Manual J8 (MJ8) and the Passive House Planning Package software. Results from that research indicate that MJ8 significantly oversizes heating systems for superinsulated homes and that thermal inertia and internal gains should be considered for more accurate load calculations.

Parametric Analysis of the feasibility of low-temperature geothermal heat recovery in sedimentary basins

Science.gov (United States)

Tomac, I.; Caulk, R.

2016-12-01

The current study explored the feasibility of heat recovery through the installation of heat exchangers in abandoned oil and gas wells. Finite Element Methods (FEM) were employed to determine the effects of various site specific parameters on production fluid temperature. Specifically, the study parameterized depth of well, subsurface temperature gradient, sedimentary rock conductivity, and flow rate. Results show that greater well depth is associated with greater heat flow, with the greatest returns occurring between depths of 1.5 km and 7 km. Beyond 7 km, the rate of return decreases due to a non-linear increase of heat flow combined with a continued linear increase of pumping cost. One cause for the drop of heat flow was the loss of heat as the fluid travels from depth to the surface. Further analyses demonstrated the benefit of an alternative heat exchanger configuration characterized by thermally insulated sections of the upward heat exchanger. These simulations predict production fluid temperature gains between 5 - 10 oC, which may be suitable for geothermal heat pump applications.

Understanding heat and groundwater flow through continental flood basalt provinces: insights gained from alternative models of permeability/depth relationships for the Columbia Plateau, USA

Science.gov (United States)

Burns, Erick R.; Williams, Colin F.; Ingebritsen, Steven E.; Voss, Clifford I.; Spane, Frank A.; DeAngelo, Jacob

2015-01-01

Heat-flow mapping of the western USA has identified an apparent low-heat-flow anomaly coincident with the Columbia Plateau Regional Aquifer System, a thick sequence of basalt aquifers within the Columbia River Basalt Group (CRBG). A heat and mass transport model (SUTRA) was used to evaluate the potential impact of groundwater flow on heat flow along two different regional groundwater flow paths. Limited in situ permeability (k) data from the CRBG are compatible with a steep permeability decrease (approximately 3.5 orders of magnitude) at 600–900 m depth and approximately 40°C. Numerical simulations incorporating this permeability decrease demonstrate that regional groundwater flow can explain lower-than-expected heat flow in these highly anisotropic (kx/kz ~ 104) continental flood basalts. Simulation results indicate that the abrupt reduction in permeability at approximately 600 m depth results in an equivalently abrupt transition from a shallow region where heat flow is affected by groundwater flow to a deeper region of conduction-dominated heat flow. Most existing heat-flow measurements within the CRBG are from shallower than 600 m depth or near regional groundwater discharge zones, so that heat-flow maps generated using these data are likely influenced by groundwater flow. Substantial k decreases at similar temperatures have also been observed in the volcanic rocks of the adjacent Cascade Range volcanic arc and at Kilauea Volcano, Hawaii, where they result from low-temperature hydrothermal alteration.

An experimental investigation of shell and tube latent heat storage for solar dryer using paraffin wax as heat storage material

Directory of Open Access Journals (Sweden)

Ashish Agarwal

2016-03-01

Full Text Available In the presented study the shell and tube type latent heat storage (LHS has been designed for solar dryer and paraffin wax is used as heat storage material. In the first part of the study, the thermal and heat transfer characteristics of the latent heat storage system have been evaluated during charging and discharging process using air as heat transfer fluid (HTF. In the last section of the study the effectiveness of the use of an LHS for drying of food product and also on the drying kinetics of a food product has been determined. A series of experiments were conducted to study the effects of flow rate and temperature of HTF on the charging and discharging process of LHS. The temperature distribution along the radial and longitudinal directions was obtained at different time during charging process to analyze the heat transfer phenomenon in the LHS. Thermal performance of the system is evaluated in terms of cumulative energy charged and discharged, during the charging and discharging process of LHS, respectively. Experimental results show that the LHS is suitable to supply the hot air for drying of food product during non-sunshine hours or when the intensity of solar energy is very low. Temperature gain of air in the range of 17 °C to 5 °C for approximately 10 hrs duration was achieved during discharging of LHS.

Weight suppression predicts total weight gain and rate of weight gain in outpatients with anorexia nervosa.

Science.gov (United States)

Carter, Frances A; Boden, Joseph M; Jordan, Jennifer; McIntosh, Virginia V W; Bulik, Cynthia M; Joyce, Peter R

2015-11-01

The present study sought to replicate the finding of Wildes and Marcus, Behav Res Ther, 50, 266-274, 2012 that higher levels of weight suppression at pretreatment predict greater total weight gain, faster rate of weight gain, and bulimic symptoms amongst patients admitted with anorexia nervosa. Participants were 56 women with anorexia nervosa diagnosed by using strict or lenient weight criteria, who were participating in a randomized controlled psychotherapy trial (McIntosh et al., Am J Psychiatry, 162, 741-747, 2005). Thirty-five women completed outpatient treatment and post-treatment assessment. Weight suppression was the discrepancy between highest lifetime weight at adult height and weight at pretreatment assessment. Outcome variables were total weight gain, rate of weight gain, and bulimic symptoms in the month prior to post-treatment assessment [assessed using the Eating Disorders Examination (Fairburn et al., Binge-Eating: Nature, Assessment and Treatment. New York: Guilford, 1993)]. Weight suppression was positively associated with total weight gain and rate of weight gain over treatment. Regression models showed that this association could not be explained by covariates (age at onset of anorexia nervosa and treatment modality). Weight suppression was not significantly associated with bulimic symptoms in the month prior to post-treatment assessment, regardless of whether bulimic symptoms were examined as continuous or dichotomous variables. The present study reinforces the previous finding that weight suppression predicts total weight gain and rate of weight gain amongst patients being treated for anorexia nervosa. Methodological issues may explain the failure of the present study to find that weight suppression predicts bulimic symptoms. Weight suppression at pretreatment for anorexia nervosa should be assessed routinely and may inform treatment planning. © 2015 Wiley Periodicals, Inc.

Multi-parameter Nonlinear Gain Correction of X-ray Transition Edge Sensors for the X-ray Integral Field Unit

Science.gov (United States)

Cucchetti, E.; Eckart, M. E.; Peille, P.; Porter, F. S.; Pajot, F.; Pointecouteau, E.

2018-04-01

With its array of 3840 Transition Edge Sensors (TESs), the Athena X-ray Integral Field Unit (X-IFU) will provide spatially resolved high-resolution spectroscopy (2.5 eV up to 7 keV) from 0.2 to 12 keV, with an absolute energy scale accuracy of 0.4 eV. Slight changes in the TES operating environment can cause significant variations in its energy response function, which may result in systematic errors in the absolute energy scale. We plan to monitor such changes at pixel level via onboard X-ray calibration sources and correct the energy scale accordingly using a linear or quadratic interpolation of gain curves obtained during ground calibration. However, this may not be sufficient to meet the 0.4 eV accuracy required for the X-IFU. In this contribution, we introduce a new two-parameter gain correction technique, based on both the pulse-height estimate of a fiducial line and the baseline value of the pixels. Using gain functions that simulate ground calibration data, we show that this technique can accurately correct deviations in detector gain due to changes in TES operating conditions such as heat sink temperature, bias voltage, thermal radiation loading and linear amplifier gain. We also address potential optimisations of the onboard calibration source and compare the performance of this new technique with those previously used.

Numerical investigation of heat transfer effects in small wave rotor

International Nuclear Information System (INIS)

Deng, Shi; Okamoto, Koji; Teramoto, Susumu

2015-01-01

Although a wave rotor is expected to enhance the performance of the ultra-micro gas turbine, the device itself may be affected by downsizing. Apart from the immediate effect of viscosity on flow dynamics when downscaled, the effects of heat transfer on flow field increase at such small scales. To gain an insight into the effects of heat transfer on the internal flow dynamics, numerical investigations were carried out with adiabatic, isothermal and conjugate heat transfer boundary treatments at the wall, and the results compared and discussed in the present study. With the light shed by the discussion of adiabatic and conjugate heat transfer boundary treatments, this work presents investigations of the heat flux distributions, as well as the effects of heat transfer on the internal flow dynamics and the consequent charging and discharging processes for various sizes. When heat transfer is taken into account, states of fluid in the cell before compression process varies, shock waves in compression process are found to be weaker, and changes in the charging and discharging processes are observed. Heat transfer differences between conjugate heat transfer boundary treatment and isothermal boundary treatment are addressed through comparisons of local wall temperature and heat flux. As a result, the difference in discharging temperature of high pressure fluid is noticeable in all sizes investigated, and the rapid increase of differences between results of isothermal and conjugate heat transfer boundary treatment in small size reveals that for certain small sizes (length of cell < 23 mm) the thermal boundary treatment should be taken care of.

Heat pipe heat exchangers in heat recovery systems

Energy Technology Data Exchange (ETDEWEB)

Stulc, P; Vasiliev, L L; Kiseljev, V G; Matvejev, Ju N

1985-01-01

The results of combined research and development activities of the National Research Institute for Machine Design, Prague, C.S.S.R. and the Institute for Heat and Mass Transfer, Minsk, U.S.S.R. concerning intensification heat pipes used in heat pipe heat exchangers are presented. This sort of research has been occasioned by increased interest in heat power economy trying to utilise waste heat produced by various technological processes. The developed heat pipes are deployed in construction of air-air, gas-air or gas-gas heat recovery exchangers in the field of air-engineering and air-conditioning. (author).

Measurement of Antenna Bore-Sight Gain

Science.gov (United States)

Fortinberry, Jarrod; Shumpert, Thomas H.

2016-01-01

The absolute or free-field gain of a simple antenna can be approximated using standard antenna theory formulae or for a more accurate prediction, numerical methods may be employed to solve for antenna parameters including gain. Both of these methods will result in relatively reasonable estimates but in practice antenna gain is usually verified and documented via measurements and calibration. In this paper, a relatively simple and low-cost, yet effective means of determining the bore-sight free-field gain of a VHF/UHF antenna is proposed by using the Brewster angle relationship.

Maximum power gains of radio-frequency-driven two-energy-component tokamak reactors

International Nuclear Information System (INIS)

Jassby, D.L.

1974-11-01

Two-energy-component fusion reactors in which the suprathermal component (D) is produced by harmonic cyclotron ''runaway'' of resonant ions are considered. In one ideal case, the fast hydromagnetic wave at ω = 2ω/sub cD/ produces an energy distribution f(W) approximately constant (up to W/sub max/) that includes all deuterons, which then thermalize and react with the cold tritons. In another ideal case, f(W) approximately constant is maintained by the fast wave at ω = ω/sub cD/. If one neglects (1) direct rf input to the bulk-plasma electrons and tritons, and (2) the fact that many deuterons are not resonantly accelerated, then the maximum ideal power gain is about 0.85 Q/sub m/ in the first case and 1.05 Q/sub m/ in the second case, where Q/sub m/ is the maximum fusion gain in the beam-injection scheme (e.g., Q/sub m/ = 1.9 at T/sub e/ = 10 keV). Because of nonideal effects, the cyclotron runaway phenomenon may find its most practical use in the heating of 50:50 D--T plasmas to ignition. (auth)

Gain scheduling using the Youla parameterization

DEFF Research Database (Denmark)

Niemann, Hans Henrik; Stoustrup, Jakob

1999-01-01

Gain scheduling controllers are considered in this paper. The gain scheduling problem where the scheduling parameter vector cannot be measured directly, but needs to be estimated is considered. An estimation of the scheduling vector has been derived by using the Youla parameterization. The use...... in connection with H_inf gain scheduling controllers....

High Gain Advanced GPS Receiver

National Research Council Canada - National Science Library

Brown, Alison; Zhang, Gengsheng

2006-01-01

NAVSYS High Gain Advanced GPS Receiver (HAGR) uses a digital beam-steering antenna array to enable up to eight GPS satellites to be tracked, each with up to 10 dBi of additional antenna gain over a conventional receiver solution...

Determination of the STIS CCD Gain

Science.gov (United States)

Riley, Allyssa; Monroe, TalaWanda; Lockwood, Sean

2016-09-01

This report summarizes the analysis and absolute gain results of the STIS Cycle 23 special calibration program 14424 that was designed to measure the gain of amplifiers A, C and D at nominal gain settings of 1 and 4 e-/DN. We used the mean-variance technique and the results indicate a mean-variance technique.

Error in interpreting field chlorophyll fluorescence measurements: heat gain from solar radiation

International Nuclear Information System (INIS)

Marler, T.E.; Lawton, P.D.

1994-01-01

Temperature and chlorophyll fluorescence characteristics were determined on leaves of various horticultural species following a dark adaptation period where dark adaptation cuvettes were shielded from or exposed to solar radiation. In one study, temperature of Swietenia mahagoni (L.) Jacq. leaflets within cuvettes increased from approximately 36C to approximately 50C during a 30-minute exposure to solar radiation. Alternatively, when the leaflets and cuvettes were shielded from solar radiation, leaflet temperature declined to 33C in 10 to 15 minutes. In a second study, 16 horticultural species exhibited a lower variable: maximum fluorescence (F v :F m ) when cuvettes were exposed to solar radiation during the 30-minute dark adaptation than when cuvettes were shielded. In a third study with S. mahagoni, the influence of self-shielding the cuvettes by wrapping them with white tape, white paper, or aluminum foil on temperature and fluorescence was compared to exposing or shielding the entire leaflet and cuvette. All of the shielding methods reduced leaflet temperature and increased the F v :F m ratio compared to leaving cuvettes exposed. These results indicate that heat stress from direct exposure to solar radiation is a potential source of error when interpreting chlorophyll fluorescence measurements on intact leaves. Methods for moderating or minimizing radiation interception during dark adaptation are recommended. (author)

Nonlinear gain of a millimetre wave antenna array mounted on a re-entry vehicle

International Nuclear Information System (INIS)

Sharma, Ashok Kumar; Kumar, Ashok

2007-01-01

A millimetre wave antenna array, mounted on a space vehicle re-entering the Earth's atmosphere, encounters a high density plasma around it. At high antenna power, the millimetre wave field heats the electrons nonuniformly. The electron temperature, T e , follows the antenna pattern, being maximum along the direction of the principal maximum (z-axis) and falling off rapidly across it. The ambipolar plasma diffusion under the pressure gradient force creates a refractive index profile with maximum on the z-axis, leading to self-convergence of the millimetre wave and enhancement in the effective gain of the antenna

Nonunity gain minimal-disturbance measurement

DEFF Research Database (Denmark)

Sabuncu, Metin; Mišta, L.; Fiurášek, J.

2007-01-01

We propose and experimentally demonstrate an optimal nonunity gain Gaussian scheme for partial measurement of an unknown coherent state that causes minimal disturbance of the state. The information gain and the state disturbance are quantified by the noise added to the measurement outcomes...

Heat transfer in Rockwool modelling and method of measurement. The effect of natural convection on heat transfer in fibrous materials

Energy Technology Data Exchange (ETDEWEB)

Dyrboel, Susanne

1998-05-01

Fibrous materials are some of the most widely used materials for thermal insulation. In this project the focus of interest has been on fibrous materials for building application. Interest in improving the thermal properties of insulation materials is increasing as legislation is being tightened to reduce the overall energy consumption. A knowledge of the individual heat transfer mechanisms - whereby heat is transferred within a particular material is an essential tool to improve continuously the thermal properties of the material. Heat is transferred in fibrous materials by four different transfer mechanisms: conduction through air, conduction through fibres, thermal radiation and convection. In a particular temperature range the conduction through air can be regarded as a constant, and conduction through fibres is an insignificant part of the total heat transfer. Radiation, however, constitutes 25-40% of the total heat transfer in light fibrous materials. In Denmark and a number of other countries convection in fibrous materials is considered as non-existent when calculating heat transmission as well as when designing building structures. Two heat transfer mechanisms have been the focus of the current project: radiation heat transfer and convection. The radiation analysis serves to develop a model that can be used in further work to gain a wider knowledge of the way in which the morphology of the fibrous material, i.e. fibre diameter distribution, fibre orientation distribution etc., influences the radiation heat transfer under different conditions. The convection investigation serves to examine whether considering convection as non-existent is a fair assumption to use in present and future building structures. The assumption applied in practically is that convection makes a notable difference only in very thick insulation, at external temperatures below -20 deg. C, and at very low densities. For large thickness dimensions the resulting heat transfer through the

Energy gains from lattice-enabled nuclear reactions

International Nuclear Information System (INIS)

Nagel, David J.

2015-01-01

The energy gain of a system is defined as the ratio of its output energy divided by the energy provided to operate the system. Most familiar systems have energy gains less than one due to various inefficiencies. By contrast, lattice-enabled nuclear reactions (LENR) offer high energy gains. Theoretical values in excess of 1000 are possible. Energy gains over 100 have already been reported. But, they have not yet been sustained for commercially significant durations. This article summarizes the current status of LENR energy gains. (author)

Charge Gain, Voltage Gain, and Node Capacitance of the SAPHIRA Detector Pixel by Pixel

Science.gov (United States)

Pastrana, Izabella M.; Hall, Donald N. B.; Baker, Ian M.; Jacobson, Shane M.; Goebel, Sean B.

2018-01-01

The University of Hawai`i Institute for Astronomy has partnered with Leonardo (formerly Selex) in the development of HgCdTe linear mode avalanche photodiode (L-APD) SAPHIRA detectors. The SAPHIRA (Selex Avalanche Photodiode High-speed Infra-Red Array) is ideally suited for photon-starved astronomical observations, particularly near infrared (NIR) adaptive optics (AO) wave-front sensing. I have measured the stability, and linearity with current, of a 1.7-um (10% spectral bandpass) infrared light emitting diode (IR LED) used to illuminate the SAPHIRA and have then utilized this source to determine the charge gain (in e-/ADU), voltage gain (in uV/ADU), and node capacitance (in fF) for each pixel of the 320x256@24um SAPHIRA. These have previously only been averages over some sub-array. Determined from the ratio of the temporal averaged signal level to variance under constant 1.7-um LED illumination, I present the charge gain pixel-by-pixel in a 64x64 sub-array at the center of the active area of the SAPHIRA (analyzed separately as four 32x32 sub-arrays) to be about 1.6 e-/ADU (σ=0.5 e-/ADU). Additionally, the standard technique of varying the pixel reset voltage (PRV) in 10 mV increments and recording output frames for the same 64x64 subarray found the voltage gain per pixel to be about 11.7 uV/ADU (σ=0.2 uV/ADU). Finally, node capacitance was found to be approximately 23 fF (σ=6 fF) utilizing the aforementioned charge and voltage gain measurements. I further discuss the linearity measurements of the 1.7-um LED used in the charge gain characterization procedure.

Effect of Various External Shading Devices on Windows for Minimum Heat Gain and Adequate Day lighting into Buildings of Hot and Dry Climatic Zone in India

Directory of Open Access Journals (Sweden)

Kirankumar Gorantla

2018-01-01

Full Text Available Glass is the major component of the building envelope to provide visual comfort to inside the buildings. In général clear and bronze glass was used as a main building envelope for both residential and commercial buildings to provide better day lighting into the buildings. If we use more glass area as a building envelope more radiation allows into the buildings. So that it is necessary to reduce more solar radiation and provide sufficient daylight factor inside the building's through glass windows with the help of external devices called shading devices. In this work four shading devices was tried on bronze glass window to find the heat gain and daylighting into buildings. This paper presents the experimental measurement of spectral characteristics of bronze glass which include transmission and reflection in entire solar spectrum region (300nm-2500nm based on ASTM standards. A MATLAB code was developed to compute visible and solar optical properties as per the British standards. A building model was designed by design builder software tool. 40% window to wall ratio was considered for building models, thermal and day lighting analysis of buildings through windows was carried out in Energy plus software tool for hot and dry climatic zone of India.

Analysis of surface roughness effects on heat transfer in micro-conduits

Energy Technology Data Exchange (ETDEWEB)

Koo, J.; Kleinstreuer, C. [North Carolina State University, Raleigh, NC (United States). Dept. of Mechanical and Aerospace Engineering

2005-06-01

Modern heat rejection systems, such as micro-heat sinks, are attractive because of their potential for high performance at small size and low weight. However, the impact of microscale effects on heat transfer have to be considered and quantitatively analyzed in order to gain physical insight and accurate Nusselt number data. The relative surface roughness (SR) was selected as a key microscale parameter, represented by a porous medium layer (PML) model. Assuming steady laminar fully developed liquid flow in microchannels and microtubes, the SR effects in terms of PML thermal conductivity ratio and Darcy number on the dimensionless temperature profile and Nusselt number were analyzed. In summary, the PML characteristics, especially the SR-number and conductivity ratio k{sub m}/k{sub f}, greatly affect the heat transfer performance where the Nusselt number can be either higher or lower than the conventional value. The PML influence is less pronounced in microtubes than in parallel-plate microchannels. (author)

Studies of electron and proton isochoric heating for fast ignition

International Nuclear Information System (INIS)

Mackinnon, A; Key, M; Akli, K; Beg, F; Clarke, R; Clarke, D; Chen, M; Chung, H; Chen, S; Freeman, R; Green, J; Gu, P; Gregori, G; Highbarger, K; Habara, H; Hatchett, S; Hey, D; Heathcote, R; Hill, J; King, J; Kodama, R; Koch, J; Lancaster, K; Langdon, B; Murphy, C; Norreys, P; Neely, D; Nakatsutsumi, M; Nakamura, H; Patel, N; Patel, P; Pasley, J; Snavley, R; Stephens, R; Stoeckl, C; Foord, M; Tabak, M; Theobald, W; Storm, M; Tanaka, K; Tempo, M; Toley, M; Town, R; Wilks, S; VanWoerkom, L; Weber, R; Yabuuchi, T; Zhang, B

2006-01-01

Isochoric heating of inertially confined fusion plasmas by laser driven MeV electrons or protons is an area of great topical interest in the inertial confinement fusion community, particularly with respect to the fast ignition (FI) proposal to use this technique to initiate burn in a fusion capsule. Experiments designed to investigate electron isochoric heating have measured heating in two limiting cases of interest to fast ignition, small planar foils and hollow cones. Data from Cu Kα fluorescence, crystal x-ray spectroscopy of Cu K shell emission, and XUV imaging at 68eV and 256 eV are used to test PIC and Hybrid PIC modeling of the interaction. Isochoric heating by focused proton beams generated at the concave inside surface of a hemi-shell and from a sub hemi-shell inside a cone have been studied with the same diagnostic methods plus imaging of proton induced Kα. Conversion efficiency to protons has also been measured and modeled. Conclusions from the proton and electron heating experiments will be presented. Recent advances in modeling electron transport and innovative target designs for reducing igniter energy and increasing gain curves will also be discussed

At what level of heat load are age-related impairments in the ability to dissipate heat evident in females?

Directory of Open Access Journals (Sweden)

Jill M Stapleton

Full Text Available Studies have reported that older females have impaired heat loss responses during work in the heat compared to young females. However, it remains unclear at what level of heat stress these differences occur. Therefore, we examined whole-body heat loss [evaporative (HE and dry heat loss, via direct calorimetry] and changes in body heat storage (∆Hb, via direct and indirect calorimetry in 10 young (23±4 years and 10 older (58±5 years females matched for body surface area and aerobic fitness (VO2peak during three 30-min exercise bouts performed at incremental rates of metabolic heat production of 250 (Ex1, 325 (Ex2 and 400 (Ex3 W in the heat (40°C, 15% relative humidity. Exercise bouts were separated by 15 min of recovery. Since dry heat gain was similar between young and older females during exercise (p=0.52 and recovery (p=0.42, differences in whole-body heat loss were solely due to HE. Our results show that older females had a significantly lower HE at the end of Ex2 (young: 383±34 W; older: 343±39 W, p=0.04 and Ex3 (young: 437±36 W; older: 389±29 W, p=0.008, however no difference was measured at the end of Ex1 (p=0.24. Also, the magnitude of difference in the maximal level of HE achieved between the young and older females became greater with increasing heat loads (Ex1=10.2%, Ex2=11.6% and Ex3=12.4%. Furthermore, a significantly greater ∆Hb was measured for all heat loads for the older females (Ex1: 178±44 kJ; Ex2: 151±38 kJ; Ex3: 216±25 kJ, p=0.002 relative to the younger females (Ex1: 127±35 kJ; Ex2: 96±45 kJ; Ex3: 146±46 kJ. In contrast, no differences in HE or ∆Hb were observed during recovery (p>0.05. We show that older habitually active females have an impaired capacity to dissipate heat compared to young females during exercise-induced heat loads of ≥325 W when performed in the heat.

Effects of combined heat and x-rays on tumours in mice

International Nuclear Information System (INIS)

Hill, S.A.

1980-08-01

The therapeutic potential of combined hyperthermia and radiation was investigated in six different types of experimental mouse tumour. Their response to hyperthermia alone and combined heat and X-ray treatments was assessed by delay in tumour regrowth. Thermal sensitivity was found to vary from tumour to tumour. The importance of the order of application and the time interval between treatments was investigated, and the tumour response compared with that of mouse skin as an example of a normal tissue. A therapeutic gain was not seen for X-rays and heat in close sequence. It was however seen when heat was applied several hours after irradiation. Constriction of the tumour blood supply, either artificially, or naturally by implantation into a constricted site, was found to increase thermal sensitivity dramatically. Possible reasons for this are discussed. Heat applied immediately before irradiation may result in a small increase in metastatic spread. Heat applied at other times did not influence the metastatic incidence. Immersion in hot water was examined as a method of heating experimental mouse tumours, and was found to be inadequate in terms of the temperature uniformity achieved. The influence of this factor on results using water bath heating are discussed. (author)

Comparison of Video Head Impulse Test (vHIT) Gains Between Two Commercially Available Devices and by Different Gain Analytical Methods.

Science.gov (United States)

Lee, Sang Hun; Yoo, Myung Hoon; Park, Jun Woo; Kang, Byung Chul; Yang, Chan Joo; Kang, Woo Suk; Ahn, Joong Ho; Chung, Jong Woo; Park, Hong Ju

2018-06-01

To evaluate whether video head impulse test (vHIT) gains are dependent on the measuring device and method of analysis. Prospective study. vHIT was performed in 25 healthy subjects using two devices simultaneously. vHIT gains were compared between these instruments and using five different methods of comparing position and velocity gains during head movement intervals. The two devices produced different vHIT gain results with the same method of analysis. There were also significant differences in the vHIT gains measured using different analytical methods. The gain analytic method that compares the areas under the velocity curve (AUC) of the head and eye movements during head movements showed lower vHIT gains than a method that compared the peak velocities of the head and eye movements. The former method produced the vHIT gain with the smallest standard deviation among the five procedures tested in this study. vHIT gains differ in normal subjects depending on the device and method of analysis used, suggesting that it is advisable for each device to have its own normal values. Gain calculations that compare the AUC of the head and eye movements during the head movements show the smallest variance.

Design of heat exchanger for Ericsson-Brayton piston engine.

Science.gov (United States)

Durcansky, Peter; Papucik, Stefan; Jandacka, Jozef; Holubcik, Michal; Nosek, Radovan

2014-01-01

Combined power generation or cogeneration is a highly effective technology that produces heat and electricity in one device more efficiently than separate production. Overall effectiveness is growing by use of combined technologies of energy extraction, taking heat from flue gases and coolants of machines. Another problem is the dependence of such devices on fossil fuels as fuel. For the combustion turbine is mostly used as fuel natural gas, kerosene and as fuel for heating power plants is mostly used coal. It is therefore necessary to seek for compensation today, which confirms the assumption in the future. At first glance, the obvious efforts are to restrict the use of largely oil and change the type of energy used in transport. Another significant change is the increase in renewable energy--energy that is produced from renewable sources. Among machines gaining energy by unconventional way belong mainly the steam engine, Stirling engine, and Ericsson engine. In these machines, the energy is obtained by external combustion and engine performs work in a medium that receives and transmits energy from combustion or flue gases indirectly. The paper deals with the principle of hot-air engines, and their use in combined heat and electricity production from biomass and with heat exchangers as primary energy transforming element.

Design of Heat Exchanger for Ericsson-Brayton Piston Engine

Directory of Open Access Journals (Sweden)

Peter Durcansky

2014-01-01

Full Text Available Combined power generation or cogeneration is a highly effective technology that produces heat and electricity in one device more efficiently than separate production. Overall effectiveness is growing by use of combined technologies of energy extraction, taking heat from flue gases and coolants of machines. Another problem is the dependence of such devices on fossil fuels as fuel. For the combustion turbine is mostly used as fuel natural gas, kerosene and as fuel for heating power plants is mostly used coal. It is therefore necessary to seek for compensation today, which confirms the assumption in the future. At first glance, the obvious efforts are to restrict the use of largely oil and change the type of energy used in transport. Another significant change is the increase in renewable energy—energy that is produced from renewable sources. Among machines gaining energy by unconventional way belong mainly the steam engine, Stirling engine, and Ericsson engine. In these machines, the energy is obtained by external combustion and engine performs work in a medium that receives and transmits energy from combustion or flue gases indirectly. The paper deals with the principle of hot-air engines, and their use in combined heat and electricity production from biomass and with heat exchangers as primary energy transforming element.

Characterization of transient gain x-ray lasers

International Nuclear Information System (INIS)

Dunn, J.; Osterheld, A.; Shlyaptsev, V.

1999-01-01

We have performed numerical simulations of the transient collisional excitation Ni-like Pd 4d → 4p J = 0 → 1 147 angstrom laser transition recently observed at Lawrence Livermore National Laboratory (LLNL). The high gain ∼35 cm results from the experiment are compared with detailed modeling simulations from the 1-D RADEX code in order to better understand the main physics issues affecting the measured gain and x-ray laser propagation along the plasma column. Simulations indicate that the transient gain lifetime associated with the short pulse pumping and refraction of the x-ray laser beam out of the gain region are the main detrimental effects. Gain lifetimes of ∼7 ps(1/e decay) are inferred from the smoothly changing gain experimental observations and are in good agreement with the simulations. Furthermore, the modeling results indicate the presence of a longer-lived but lower gain later in time associated with the transition from transient to quasi-steady state excitation

Controlling gain one photon at a time

Science.gov (United States)

Schwartz, Gregory W; Rieke, Fred

2013-01-01

Adaptation is a salient property of sensory processing. All adaptational or gain control mechanisms face the challenge of obtaining a reliable estimate of the property of the input to be adapted to and obtaining this estimate sufficiently rapidly to be useful. Here, we explore how the primate retina balances the need to change gain rapidly and reliably when photons arrive rarely at individual rod photoreceptors. We find that the weakest backgrounds that decrease the gain of the retinal output signals are similar to those that increase human behavioral threshold, and identify a novel site of gain control in the retinal circuitry. Thus, surprisingly, the gain of retinal signals begins to decrease essentially as soon as background lights are detectable; under these conditions, gain control does not rely on a highly averaged estimate of the photon count, but instead signals from individual photon absorptions trigger changes in gain. DOI: http://dx.doi.org/10.7554/eLife.00467.001 PMID:23682314

Active metamaterial: Gain and stability, and microfluidic chip for THz cell spectroscopy

Science.gov (United States)

Tang, Qi

Metamaterials are artificially designed composite materials which can exhibit unique and unusual properties such as the negative refractive index, negative phase velocity, etc. The concept of metamaterials becomes prevalent in the electromagnetic society since the first experimental implementation in the early 2000s. Many fascinated potential applications, e.g. super lens, invisibility cloaking, and novel antennas that are electrically small, have been proposed based on metamaterials. However, most of the applications still remain in theory and are not suitable for practical applications mainly due to the intrinsic loss and narrow bandwidth (large dispersion) determined by the fundamental physics of metamaterials. In this dissertation, we incorporate active gain devices into conventional passive metamaterials to overcome loss and even provide gain. Two types of active gain negative refractive index metamaterials are proposed, designed and experimentally demonstrated, including an active composite left-/right-handed transmission line and an active volumetric metamaterial. In addition, we investigate the non-Foster circuits for broadband matching of electrically small antennas. A rigorous way of analyzing the stability of non-Foster circuits by normalized determinant function is proposed. We study the practical factors that may affect the stability of non-Foster circuits, including the device parasitics, DC biasing, layouts and load impedance. A stable floating negative capacitor is designed, fabricated and tested. Moreover, it is important to resolve the sign of refractive index for active gain media which can be quite challenging. We investigate the analytical solution of a gain slab system, and apply the Nyquist criterion to analyze the stability of a causal gain medium. We then emphasize that the result of frequency domain simulation has to be treated with care. Lastly, this dissertation discusses another interesting topic about THz spectroscopy of live cells

Low-grade heat and its definitions of Coefficient-of-Performance (COP)

International Nuclear Information System (INIS)

Wang, Lin-Shu; Ma, Peizheng

2015-01-01

Use of fire for low grade heat, still widely practiced today, is wasteful because it is based on the principle of heat production – which should have become an outmoded idea post-Carnot for low grade heat application as an exergy analysis will readily conclude. Instead of application of exergy analysis, a new thermodynamic analysis resulting from the unification of Kelvin's energy principle and the entropy principle, formulated recently (called the entropic theory of heat), is applied here to reexamine the problem of building heating. Other than improving envelope heat resistance, conventional building efficiency gain is predominantly obtained by improving HVAC efficiency (i.e., boiler efficiency); our finding shows that there is in fact large room in improving the building heating operation surpassing 100% boiler efficiency, as demonstrated by the large value of the Kelvin limit (the theoretical upper bound of Thermal COP). This theoretical possibility of generous amount of heat from fire suggests additional possibilities of heat from primary energy other than fire, and the disclosure of these possibilities by applying the triad framework in the entropic theory of heat in terms of alternative definitions of Coefficient of Performance (COP). Consideration of such alternative COPs suggests real possibility of efficiently and cost effectively obtaining low grade heat from primary energy. - Highlights: • Importance of thinking heat extraction for high energy efficiency in buildings. • The concept of Thermal COP and the determination of its (maximum) Kelvin limit. • Key to find the sweet spot of using heat pump is thinking general heat extraction. • triadCOP &eThermalCOP are measure of energy transformation in the triad framework

Wind power integration with heat pumps, heat storages, and electric vehicles - Energy systems analysis and modelling

Energy Technology Data Exchange (ETDEWEB)

Hedegaard, K.

2013-09-15

This PhD investigates to which extent heat pumps, heat storages, and electric vehicles can support the integration of wind power. Considering the gaps in existing research, the main focus is put on individual heat pumps in the residential sector (one-family houses) and the possibilities for flexible operation, using the heat storage options available. Several energy systems analyses are performed using the energy system models, Balmorel, developed at the former TSO, ElkraftSystem, and, EnergyPLAN, developed at Aalborg University. The Danish energy system towards 2030, with wind power penetrations of up to 60 %, is used as a case study in most of the analyses. Both models have been developed further, resulting in an improved representation of individual heat pumps and heat storages. An extensive model add-on for Balmorel renders it possible to optimise investment and operation of individual heat pumps and different types of heat storages, in integration with the energy system. Total costs of the energy system are minimised in the optimisation. The add-on incorporates thermal building dynamics and covers various different heat storage options: intelligent heat storage in the building structure for houses with radiator heating and floor heating, respectively, heat accumulation tanks on the space heating circuit, as well as hot water tanks. In EnergyPLAN, some of the heat storage options have been modelled in a technical optimisation that minimises fuel consumption of the energy system and utilises as much wind power as possible. The energy systems analyses reveal that in terms of supporting wind power integration, the installation of individual heat pumps is an important step, while adding heat storages to the heat pumps is less influential. When equipping the heat pumps with heat storages, only moderate system benefits can be gained. Hereof, the main system benefit is that the need for peak/reserve capacity investments can be reduced through peak load shaving; in

Effect of heat stress on six beef breeds in the Zastron district: The ...

African Journals Online (AJOL)

A study was done to determine which factors had the greatest influence on a heifer's susceptibility to heat stress. Parameters tested were breed, coat colour, coat score, hide thickness, weight gain, respiration rate and body condition score. The study was conducted in the southeastern Free State. Afrikaner, Bonsmara ...

Climate change and health: Indoor heat exposure in vulnerable populations

International Nuclear Information System (INIS)

White-Newsome, Jalonne L.; Sánchez, Brisa N.; Jolliet, Olivier; Zhang, Zhenzhen; Parker, Edith A.; Timothy Dvonch, J.; O'Neill, Marie S.

2012-01-01

Introduction: Climate change is increasing the frequency of heat waves and hot weather in many urban environments. Older people are more vulnerable to heat exposure but spend most of their time indoors. Few published studies have addressed indoor heat exposure in residences occupied by an elderly population. The purpose of this study is to explore the relationship between outdoor and indoor temperatures in homes occupied by the elderly and determine other predictors of indoor temperature. Materials and methods: We collected hourly indoor temperature measurements of 30 different homes; outdoor temperature, dewpoint temperature, and solar radiation data during summer 2009 in Detroit, MI. We used mixed linear regression to model indoor temperatures' responsiveness to weather, housing and environmental characteristics, and evaluated our ability to predict indoor heat exposures based on outdoor conditions. Results: Average maximum indoor temperature for all locations was 34.85 °C, 13.8 °C higher than average maximum outdoor temperature. Indoor temperatures of single family homes constructed of vinyl paneling or wood siding were more sensitive than brick homes to outdoor temperature changes and internal heat gains. Outdoor temperature, solar radiation, and dewpoint temperature predicted 38% of the variability of indoor temperatures. Conclusions: Indoor exposures to heat in Detroit exceed the comfort range among elderly occupants, and can be predicted using outdoor temperatures, characteristics of the housing stock and surroundings to improve heat exposure assessment for epidemiological investigations. Weatherizing homes and modifying home surroundings could mitigate indoor heat exposure among the elderly.

Simulation of exhaust gas heat recovery from a spray dryer

International Nuclear Information System (INIS)

Golman, Boris; Julklang, Wittaya

2014-01-01

This study explored various alternatives in improving the energy utilization of spray drying process through the exhaust gas heat recovery. Extensible and user-friendly simulation code was written in Visual Basic for Applications within Microsoft Excel for this purpose. The effects of process parameters were analyzed on the energy efficiency and energy saving in the industrial-scale spray drying system with exhaust gas heat recovery in an air-to-air heat exchanger and in the system with partial recirculation of exhaust air. The spray dryer is equipped with an indirect heater for heating the drying air. The maximum gains of 16% in energy efficiency and 50% in energy saving were obtained for spray drying system equipped with heat exchanger for exhaust air heat recovery. In addition, 34% in energy efficiency and 61% in energy saving for system with recirculation of exhaust air in the present range of process parameters. The high energy efficiency was obtained during drying of large amount of dilute slurry. The energy saving was increased using the large amount of hot drying air. - Highlights: • We model industrial-scale spray drying process with the exhaust gas heat recovery. • We develop an Excel VBA computer program to simulate spray dryer with heat recovery. • We examine effects of process parameters on energy efficiency and energy saving. • High energy efficiency is obtained during drying of large amount of dilute slurry. • Energy saving is increased using the large amount of hot drying air

Comments on the current status of aquaculture in heated effluents in North America

International Nuclear Information System (INIS)

Ayles, G.B.

1976-01-01

At the current rate of increase the world demand for fish protein will soon far exceed the supply. The culture of aquatic organisms in low-grade waste heat could be a significant source of animal protein. There are at present thriving trout culture and catfish culture industries in North America. There are a number of small-scale research and commercial aquaculture projects currently in operation and numerous studies have been carried out. However, the knowledge gained has not had a significant impact on waste heat aquaculture development. (author)

An efficient approach to characterizing and calculating carrier loss due to heating and barrier height variation in vertical-cavity surface-emitting lasers

International Nuclear Information System (INIS)

Jian, Wu; Summers, H. D.

2010-01-01

It is important to determine quantitatively the internal carrier loss arising from heating and barrier height variation in a vertical-cavity surface-emitting quantum well laser (VCSEL). However, it is generally difficult to realize this goal using purely theoretical formulas due to difficulty in deriving the parameters relating to the quantum well structure. In this paper, we describe an efficient approach to characterizing and calculating the carrier loss due to the heating and the barrier height change in the VCSEL. In the method, the thermal carrier loss mechanism is combined with gain measurement and calculation. The carrier loss is re-characterized in a calculable form by constructing the threshold current and gain detuning-related loss current using the measured gain data and then substituting them for the quantum well-related parameters in the formula. The result can be expressed as a product of an exponential weight factor linked to the barrier height change and the difference between the threshold current and gain detuning-related loss current. The gain variation at cavity frequency due to thermal carrier loss and gain detuning processes is measured by using an AlInGaAs–AlGaAs VCSEL structure. This work provides a useful approach to analysing threshold and loss properties of the VCSEL, particularly, gain offset design for high temperature operation of VCSELs. (classical areas of phenomenology)

Geothermal waste heat utilization from in situ thermal bitumen recovery operations.

Science.gov (United States)

Nakevska, Nevenka; Schincariol, Robert A; Dehkordi, S Emad; Cheadle, Burns A

2015-01-01

In situ thermal methods for bitumen extraction introduce a tremendous amount of energy into the reservoirs raising ambient temperatures of 13 °C to as high as 200 °C at the steam chamber edge and 50 °C along the reservoir edge. In essence these operations have unintentionally acted as underground thermal energy storage systems which can be recovered after completion of bitumen extraction activities. Groundwater flow and heat transport models of the Cold Lake, Alberta, reservoir, coupled with a borehole heat exchanger (BHE) model, allowed for investigating the use of closed-loop geothermal systems for energy recovery. Three types of BHEs (single U-tube, double U-tube, coaxial) were tested and analyzed by comparing outlet temperatures and corresponding heat extraction rates. Initial one year continuous operation simulations show that the double U-tube configuration had the best performance producing an average temperature difference of 5.7 °C, and an average heat extraction of 41 W/m. Given the top of the reservoir is at a depth of 400 m, polyethylene piping provided for larger extraction gains over more thermally conductive steel piping. Thirty year operation simulations illustrate that allowing 6 month cyclic recovery periods only increases the loop temperature gain by a factor of 1.2 over continuous operation. Due to the wide spacing of existing boreholes and reservoir depth, only a small fraction of the energy is efficiently recovered. Drilling additional boreholes between existing wells would increase energy extraction. In areas with shallower bitumen deposits such as the Athabasca region, i.e. 65 to 115 m deep, BHE efficiencies should be larger. © 2014, National Ground Water Association.

Experimental and numerical contribution to heat transfer enhancement in compact plate heat exchangers - 15563

International Nuclear Information System (INIS)

Vitillo, F.; Cachon, L.; Millan, P.

2015-01-01

In the framework of the CEA program to develop an industrial prototype of sodium-cooled fast reactor named (ASTRID), the present work aims at proposing an innovative compact heat exchanger technology, to provide solid technological basis for the utilization of a Brayton power conversion system. This allows avoiding the energetic sodium-water interaction that could potentially occur if a traditional Rankine cycle was used. The design of the gas-side (which determines the heat transfer resistance of the heat exchanger) of the sodium-gas heat exchanger has been the object of the present work. Compact technologies are necessary for the present application because of the low heat transfer capacity of the gas foreseen, i.e. nitrogen. The basic idea of this work is to design a channel were the fluid flow is as much as 3-dimensional as possible. In particular the proposed channel can be thought as the result of the superposition of 2 single PCHE wavy channels in phase opposition. The innovative channel geometry has to be studied numerically and experimentally to demonstrate its industrial interest and the final compact gain. To numerically provide a physically-consistent model, a new non-linear eddy viscosity named Anisotropic Shear Stress Transport (ASST) model has been developed and implemented into the available solver ANSYS FLUENT. It has been demonstrated that the ASST model can provide a valuable alternative to more complex models. Given the innovation of the proposed geometry, no test case has been found in the literature to be fully applicable to the present study. So, 3 experimental facilities have been used to acquire an extensive aerodynamic database. The Laser Doppler Velocimetry (LDV), Particle Image Velocimetry (PIV) and VHEGAS facilities have been built to investigate the innovative channel flow and heat transfer characteristics. The ASST model, used with a SGDH turbulent heat flux model, has been validate against the acquired thermal-hydraulic database

Competition to provide heat in Kosice

International Nuclear Information System (INIS)

Haluza, I.

2007-01-01

Replacing political nominees at state-owned companies after each change of the cabinet has become a standard. The consequences are all too well-known. In the best case, the company gets a manager that is an expert in the given area and in the worst case the new manager is a person who does not have the vaguest idea of the business and the only reason he has taken the position is to collect the salary. And in addition to this they might harm the company due to a lack of experience and expertise. These post-election changes often remove capable people from company management that do not have friends in the new cabinet but do not wish to leave the business. Over the years, they gained experience so why not start up a new company in the same business area. And heat supply in Kosice is a good example. For many years, there was only one heat supplier in Kosice, the state-owned joint stock company Teplaren Kosice (TEKO). It uses natural gas and coal from Russia. But at the end of last year, a new private limited liability company, Teplarenska spolocnost, was established. And it plans to build a new heating plant using wooden bio-mass for about 300 mil. Sk (8.82 mil. EUR) to compete with TEKO. The owners and managers of the company include former employees of the state-owned heating plant. (author)

Heat pipe heat storage performance

Energy Technology Data Exchange (ETDEWEB)

Caruso, A; Pasquetti, R [Univ. de Provence, Marseille (FR). Inst. Universitaire des Systemes; Grakovich, L P; Vasiliev, L L [A.V. Luikov Heat and Mass Transfer Inst. of the BSSR, Academy of Sciences, Minsk (BY)

1989-01-01

Heat storage offers essential thermal energy saving for heating. A ground heat store equipped with heat pipes connecting it with a heat source and to the user is considered in this paper. It has been shown that such a heat exchanging system along with a batch energy source meets, to a considerable extent, house heating requirements. (author).

Development of a plastic rotary heat exchanger for room-based ventilation in existing apartments

DEFF Research Database (Denmark)

Smith, Kevin Michael; Svendsen, Svend

2015-01-01

The existing building stock will likely undergo widespread energy renovations to meet future emissions targets. Single-room ventilation may enable the process due to its simple installation, low fan power, and potential for local heat recovery. A short plastic rotary heat exchanger is developed...... for single-room ventilation based on thermal design theory. Performance is predicted from correlations of dimensionless groups for regenerative heat exchangers, and this guides the selection of a polycarbonate honeycomb with small circular channels. Experiments quantify flows and determine temperature...... efficiencies at several ventilation rates while accounting for heat gains from motors and air leakage. The measured and modelled temperature efficiencies show adequate agreement and exceed 80% for a balanced nominal ventilation rate of 28m3/h. This result meets the development criteria but cannot validate...

Absorptivity Measurements and Heat Source Modeling to Simulate Laser Cladding

Science.gov (United States)

Wirth, Florian; Eisenbarth, Daniel; Wegener, Konrad

The laser cladding process gains importance, as it does not only allow the application of surface coatings, but also additive manufacturing of three-dimensional parts. In both cases, process simulation can contribute to process optimization. Heat source modeling is one of the main issues for an accurate model and simulation of the laser cladding process. While the laser beam intensity distribution is readily known, the other two main effects on the process' heat input are non-trivial. Namely the measurement of the absorptivity of the applied materials as well as the powder attenuation. Therefore, calorimetry measurements were carried out. The measurement method and the measurement results for laser cladding of Stellite 6 on structural steel S 235 and for the processing of Inconel 625 are presented both using a CO2 laser as well as a high power diode laser (HPDL). Additionally, a heat source model is deduced.

Simulation methods of rocket fuel refrigerating with liquid nitrogen and intermediate heat carrier

Directory of Open Access Journals (Sweden)

O. E. Denisov

2014-01-01

the simulator and its parts.In the proposed algorithm of calculations a simulator consists of three blocks with data and intermediate results exchange with each other. Blocks contain subsimulator of heat gain in the LPC and heat carrier circulation loops, cooling-heating subsimulator of LPC and the heat carrier in the heat exchanger and heat exchange subsimulator of LPC and heat carrier in its tanks. Functional dependence of thermophysical properties of LPC and heat carrier and its temperatures, as well as characteristics of the pumps are taken into consideration in calculations. Pump heat gain subsimulator includes hydrauliccirculation loop calculation and the calculation of the heat flow emitted by pump. Subsimulator of the heat exchanger is based on differential equations of static heat exchange, where the integration variable is length coordinate of heat exchanger. The output data of these subsimulators are input data in heat exchange subsimulator of LPC and heat carrier in its tanks, which is based on the differential equations of quasi-stationary heat exchange.Simulation results are interpolated functions of LPC, heat carrier and the metal shells temperatures. Analyzing these functions graphs one can determine the performance indicators of the refrigerating system: refrigerating time and the relative costs of liquid nitrogen (mass of liquid nitrogen spent, referred to the weight of the refrigerated LPC. For example in the case of refrigerating portions 13260 kg and 3300 kg of high-boiling oxidizer with various combinations of design and functional parameters the refrigeration time is 2.8 ... 78.3 hours, and the relative costs of nitrogen amounted to 0,178 ... 0,322.Concluded the possibility of applying the proposed method for LPC refrigeration simulation with ground equipment systems using liquid nitrogen and intermediate heat carrier to determine rational design and functional parameters of the system, which allow to achieve the lowest cost of liquid nitrogen.

Water-tunnel studies of heat balance in swimming mako sharks.

Science.gov (United States)

Bernal, D; Sepulveda, C; Graham, J B

2001-12-01

The mako shark (Isurus oxyrinchus) has specialized vascular networks (retia mirabilia) forming counter-current heat exchangers that allow metabolic heat retention in certain regions of the body, including the aerobic, locomotor red muscle and the viscera. Red muscle, white muscle and stomach temperatures were measured in juvenile (5-13.6 kg) makos swimming steadily in a water tunnel and exposed to stepwise square-wave changes in ambient temperature (T(a)) to estimate the rates of heat transfer and to determine their capacity for the activity-independent control of heat balance. The rates of heat gain of red muscle during warming were significantly higher than the rates of heat loss during cooling, and neither the magnitude of the change in T(a) nor the direction of change in T(a) had a significant effect on red muscle latency time. Our findings for mako red muscle are similar to those recorded for tunas and suggest modulation of retial heat-exchange efficiency as the underlying mechanism controlling heat balance. However, the red muscle temperatures measured in swimming makos (0.3-3 degrees C above T(a)) are cooler than those measured previously in larger decked makos. Also, the finding of non-stable stomach temperatures contrasts with the predicted independence from T(a) recorded in telemetry studies of mako and white sharks. Our studies on live makos provide new evidence that, in addition to the unique convergent morphological properties between makos and tunas, there is a strong functional similarity in the mechanisms used to regulate heat transfer.

A computational model for heterogeneous heating during pulsed laser irradiation of polymers doped with light-absorbing microparticles

DEFF Research Database (Denmark)

Marla, Deepak; Zhang, Yang; Jabbaribehnam, Mirmasoud

2016-01-01

characteristics. This work presents a study based on a computational model of laser heating of polymer doped with light-absorbing microparticles accounting for the heterogeneous nature of heating. The work aims at gaining a fundamental insight into the nature of the heating process and to understand the role......Doping of polymers with light-absorbing microparticles to increase their optical properties is a commonly used pre-treatment technique in laser processing of polymers. The presence of these particles plays an important role during laser heating of the polymer that influences its surface...... of microparticles. The results suggest that apart from the laser intensity and pulse duration, the properties of the microparticles including their size and distribution also play an important role during the laser heating of polymers....

Basic considerations for the mechanical design of heating reactors

International Nuclear Information System (INIS)

Rau, P.

1997-01-01

The paper discusses the principal aspects of the mechanical design of the reactor unit for a nuclear district heating plant. It is reasoned that the design must be specifically tailored to the characteristics of the applications, and that the experience gained with the design practice of big nuclear power stations must also be incorporated. Some examples of the design solutions for the SIEMENS NRH-200 are presented for illustration. (author). 7 refs, 10 figs

Basic considerations for the mechanical design of heating reactors

Energy Technology Data Exchange (ETDEWEB)

Rau, P [Siemens AG, Unternehmensbereich KWU, Erlangen (Germany)

1997-09-01

The paper discusses the principal aspects of the mechanical design of the reactor unit for a nuclear district heating plant. It is reasoned that the design must be specifically tailored to the characteristics of the applications, and that the experience gained with the design practice of big nuclear power stations must also be incorporated. Some examples of the design solutions for the SIEMENS NRH-200 are presented for illustration. (author). 7 refs, 10 figs.

Heating efficiency in magnetic nanoparticle hyperthermia

International Nuclear Information System (INIS)

Deatsch, Alison E.; Evans, Benjamin A.

2014-01-01

Magnetic nanoparticles for hyperthermic treatment of cancers have gained significant attention in recent years. In magnetic hyperthermia, three independent mechanisms result in thermal energy upon stimulation: Néel relaxation, Brownian relaxation, and hysteresis loss. The relative contribution of each is strongly dependent on size, shape, crystalline anisotropy, and degree of aggregation or agglomeration of the nanoparticles. We review the effects of each of these physical mechanisms in light of recent experimental studies and suggest routes for progress in the field. Particular attention is given to the influence of the collective behaviors of nanoparticles in suspension. A number of recent studies have probed the effect of nanoparticle concentration on heating efficiency and have reported superficially contradictory results. We contextualize these studies and show that they consistently indicate a decrease in magnetic relaxation time with increasing nanoparticle concentration, in both Brownian- and Néel-dominated regimes. This leads to a predictable effect on heating efficiency and alleviates a significant source of confusion within the field. - Highlights: • Magnetic nanoparticle hyperthermia. • Heating depends on individual properties and collective properties. • We review recent studies with respect to loss mechanisms. • Collective behavior is a key source of confusion in the field. • We contextualize recent studies to elucidate consistencies and alleviate confusion

Optimal Ground Source Heat Pump System Design

Energy Technology Data Exchange (ETDEWEB)

Ozbek, Metin [Environ Holdings Inc., Princeton, NJ (United States); Yavuzturk, Cy [Univ. of Hartford, West Hartford, CT (United States); Pinder, George [Univ. of Vermont, Burlington, VT (United States)

2015-04-01

Despite the facts that GSHPs first gained popularity as early as the 1940’s and they can achieve 30 to 60 percent in energy savings and carbon emission reductions relative to conventional HVAC systems, the use of geothermal energy in the U.S. has been less than 1 percent of the total energy consumption. The key barriers preventing this technically-mature technology from reaching its full commercial potential have been its high installation cost and limited consumer knowledge and trust in GSHP systems to deliver the technology in a cost-effective manner in the market place. Led by ENVIRON, with support from University Hartford and University of Vermont, the team developed and tested a software-based a decision making tool (‘OptGSHP’) for the least-cost design of ground-source heat pump (‘GSHP’) systems. OptGSHP combines state of the art optimization algorithms with GSHP-specific HVAC and groundwater flow and heat transport simulation. The particular strength of OptGSHP is in integrating heat transport due to groundwater flow into the design, which most of the GSHP designs do not get credit for and therefore are overdesigned.

Predictive Variable Gain Iterative Learning Control for PMSM

Directory of Open Access Journals (Sweden)

Huimin Xu

2015-01-01

Full Text Available A predictive variable gain strategy in iterative learning control (ILC is introduced. Predictive variable gain iterative learning control is constructed to improve the performance of trajectory tracking. A scheme based on predictive variable gain iterative learning control for eliminating undesirable vibrations of PMSM system is proposed. The basic idea is that undesirable vibrations of PMSM system are eliminated from two aspects of iterative domain and time domain. The predictive method is utilized to determine the learning gain in the ILC algorithm. Compression mapping principle is used to prove the convergence of the algorithm. Simulation results demonstrate that the predictive variable gain is superior to constant gain and other variable gains.

Impact of heat load location and strength on air flow pattern with a passive chilled beam system

Energy Technology Data Exchange (ETDEWEB)

Kosonen, Risto [Halton Oy, Niittyvillankuja 4, 01510 Vantaa (Finland); Saarinen, Pekka; Koskela, Hannu [Finnish Institute of Occupational Health, Lemminkaisenkatu 14-18 B, 20520 Turku (Finland); Hole, Alex [Arup, Rob Leslie-Carter, Level 10, 201 Kent Street, Sydney, NSW 2000 (Australia)

2010-01-15

A passive chilled beam is a source of natural convection, creating a flow of cold air directly into the occupied zone. Experiments were conducted in a mock-up of an office room to study the air velocities in the occupied spaces. In addition, velocity profiles are registered when underneath heat loads exist and the cool and warm air flows interact. Experimental laboratory study revealed that in the case of the underneath heat gains, even no upward plume was generated and the dummy only acted as a flow obstacle, having a significant effect on the velocity profile. Furthermore, in an actual occupied office environment, the thermal plumes and the supply air diffuser mixed effectively the whole air volume. The maximum air velocity measured was still below 0.25 m/s with the extremely high heat gain of 164 W/m{sup 2}. The results demonstrate that analysis methods were the interaction of convection flow and jet are not taken into account could not accurately describe air movement and draught risk in the occupied room space. (author)

Weight gain - unintentional

Science.gov (United States)

... diabetes Hormone changes or medical problems can also cause unintentional weight gain. This may be due to: Cushing syndrome Underactive thyroid, or low thyroid (hypothyroidism) Polycystic ovary syndrome Menopause Pregnancy Bloating, or swelling ...

Acoustic emission of heat treated compared graphite iron under 873-1173 K

Energy Technology Data Exchange (ETDEWEB)

Nam, Ki Woo; Lee, Soo Chul [Pukyong National University, Busan (Korea, Republic of); Ahn, Byung Kun [Korea Polytechnic, Busan Campus, Busan (Korea, Republic of)

2013-10-15

CGI is gaining popularity in applications that require either greater strength, or lower weight than cast iron. Recently, compacted graphite iron has been used for diesel engine blocks, turbo housings and exhaust manifolds. This paper were assessed acoustic emission characteristics according to the mechanical properties change of degraded CGI340 during 1-24 hours at 873-1173 K. In results of pencil lead fracture test, the dominant frequency and the velocity of base metal were 97 kHz and 5490 m/sec, respectively. The base metal in a tensile test was obtained relatively high dominant frequency. However, the heat treated materials, the longer the heat treatment time, the higher the heat treatment temperature, were obtained in the area of lower frequencies. This phenomenon appears by long-term use.

Acoustic emission of heat treated compared graphite iron under 873-1173 K

International Nuclear Information System (INIS)

Nam, Ki Woo; Lee, Soo Chul; Ahn, Byung Kun

2013-01-01

CGI is gaining popularity in applications that require either greater strength, or lower weight than cast iron. Recently, compacted graphite iron has been used for diesel engine blocks, turbo housings and exhaust manifolds. This paper were assessed acoustic emission characteristics according to the mechanical properties change of degraded CGI340 during 1-24 hours at 873-1173 K. In results of pencil lead fracture test, the dominant frequency and the velocity of base metal were 97 kHz and 5490 m/sec, respectively. The base metal in a tensile test was obtained relatively high dominant frequency. However, the heat treated materials, the longer the heat treatment time, the higher the heat treatment temperature, were obtained in the area of lower frequencies. This phenomenon appears by long-term use.

Heat-Induced Changes in Heat Shock Protein Genes Expression in Crossbred and Baladi Pregnant Cows and Their Offspring

International Nuclear Information System (INIS)

Khalil, W.K.B.; Nessim, M.Z.; El- Masry, K.A.

2010-01-01

The experiment was carried out during August (hot climate) on twelve pregnant cows of six crossbred (50% native Baladi and 50% Brown Swiss) and six native Baladi pregnant cows in the same age and the second parity during their mid-pregnancy as detected by rectal palpation. The experiment was repeated during December (mild climate) on similar twelve pregnant cows. Blood sample was obtained from each cow at the end of August (first group) and at the end of December (second group) to obtain heat shock protein genes expression (HSP72, HSP70.01, HSP70, HSP47, k Dalton and Actin) in pregnant cows under mild and hot climate to find out, which breed is more tolerant to heat stress and to estimate offspring birth weight and their growth performances during suckling period. Comparison was made between hot climate cows group and mild climate cows group to estimate heat- induced changes in both breeds in expression level of the Hsp genes and to compare with their neonate birth weight and growth performances during suckling period. The results revealed that expression level of the Hsp genes (Hsp72, Hsp70.1, Hsp70 and Hsp 47) was higher (p<0.01) in hot season compared to that of mild season. Expression level of the Hsp genes (Hsp70.1, Hsp70 and Hsp 47) was higher (p<0.05) in crossbred cows than in Baldi cows under summer hot season. This indicates that crossbred cows are less heat tolerant than Baladi cows under heat stress climate. Heat induced decrease (p<0.01) in offspring birth weight in Baladi and crossbred by 18.1% and 25%, respectively, in weaning weight by 14.61% and 23.14%, respectively and in body weight gain by 14.61% and 21.18%, respectively

CONDITIONS FOR CSR MICROBUNCHING GAIN SUPPRESSION

Energy Technology Data Exchange (ETDEWEB)

Tsai, Cheng Ying [Virginia Polytechnic Inst. and State Univ. (Virginia Tech), Blacksburg, VA (United States); Douglas, David R. [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Li, Rui [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Tennant, Christopher D. [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); di Mitri, Simone [Elettra–Sincrotrone Trieste, 34149 Basovizza, Trieste, Italy

2016-05-01

The coherent synchrotron radiation (CSR) of a high brightness electron beam traversing a series of dipoles, such as transport arcs, may result in phase space degradation. On one hand, the CSR can perturb electron transverse motion in dispersive regions along the beamline, causing emittance growth. On the other hand, the CSR effect on the longitudinal beam dynamics could result in microbunching gain enhancement. For transport arcs, several schemes have been proposed* to suppress the CSR-induced emittance growth. Similarly, several scenarios have been introduced** to suppress CSR-induced microbunching gain, which however mostly aim for linac-based machines. In this paper we try to provide sufficient conditions for suppression of CSR-induced microbunching gain along a transport arc, analogous to*. Several example lattices are presented, with the relevant microbunching analyses carried out by our semi-analytical Vlasov solver***. The simulation results show that lattices satisfying the proposed conditions indeed have microbunching gain suppressed. We expect this analysis can shed light on lattice design approach that could suppress the CSR-induced microbunching gain.

Micro scale CHP based on biomass intelligent heat transfer with thermoelectric generators

Energy Technology Data Exchange (ETDEWEB)

Moser, W.; Aigenbauer, S.; Heckmann, M.; Friedl, G. (Austrian Bioenergy Centre GmbH, Wieselburg (Austria)); Hofbauer, H. (Institute of Chemical Engineering, Vienna University of Technology (Austria))

2007-07-01

Pellet burners need auxiliary electrical power to provide CO{sub 2} balanced heat in a comfortable and environment friendly way. The idea is to produce this and some extra electricity within the device in order to save resources and to gain operation reliability and independency. An option for micro scale CHP is the usage of thermoelectric generators (TEGs). They allow direct conversion of heat into electrical power. They have the advantage of a long maintenance free durability and noiseless operation without moving parts or any working fluid. The useful heat remains almost unaffected and can still be used for heating. TEGs are predestined for the use in micro scale CHP based on solid biomass. In this paper the first results from the fully integrated prototype are presented. The performance of the TEG was observed for different loads and operating conditions in order to realise an optimised micro scale CHP based on solid biomass. (orig.)

Effect of foam on temperature prediction and heat recovery potential from biological wastewater treatment.

Science.gov (United States)

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. Copyright © 2016 Elsevier Ltd. All rights reserved.

Performance investigation of a waste heat-driven 3-bed 2-evaporator adsorption cycle for cooling and desalination

KAUST Repository

Thu, Kyaw; Saha, Bidyut Baran; Chua, Kian Jon; Ng, Kim Choon

2016-01-01

Environment-friendly adsorption (AD) cycles have gained much attention in cooling industry and its applicability has been extended to desalination recently. AD cycles are operational by low-temperature heat sources such as exhaust gas from processes

FEL gain optimisation and spontaneous radiation

Energy Technology Data Exchange (ETDEWEB)

Bali, L.M.; Srivastava, A.; Pandya, T.P. [Lucknow Univ. (India)] [and others

1995-12-31

Colson have evaluated FEL gains for small deviations from perfect electron beam injection, with radiation of the same polarisation as that of the wiggler fields. We find that for optimum gain the polarisation of the optical field should be the same as that of the spontaneous emission under these conditions. With a helical wiggler the axial oscillations resulting from small departures from perfect electron beam injection lead to injection dependent unequal amplitudes and phases of the spontaneous radiation in the two transverse directions. Viewed along the axis therefore the spontaneous emission is elliptically polarised. The azimuth of the ellipse varies with the difference of phase of the two transverse components of spontaneous emission but the eccentricity remains the same. With planar wigglers the spontaneous emission viewed in the axial direction is linearly polarised, again with an injection dependent azimuth. For optimum coherent gain of a radiation field its polarisation characteristics must be the same as those of the spontaneous radiation with both types of wiggler. Thus, with a helical wiggler and the data reported earlier, an increase of 10% in the FEL gain at the fundamental frequency and of 11% at the fifth harmonic has been calculated in the small gain per pass limit. Larger enhancements in gain may result from more favourable values of input parameters.

Foundation heat transfer analysis for buildings with thermal piles

International Nuclear Information System (INIS)

Almanza Huerta, Luis Enrique; Krarti, Moncef

2015-01-01

Highlights: • A numerical transient thermal model for thermo-active foundations is developed. • Thermal interactions between thermal piles and building foundations are evaluated. • A simplified analysis method of thermal interactions between thermal piles and building foundations is developed. - Abstract: Thermal piles or thermo-active foundations utilize heat exchangers embedded within foundation footings to heat and/or cool buildings. In this paper, the impact of thermal piles on building foundation heat transfer is investigated. In particular, a simplified analysis method is developed to estimate the annual ground-coupled foundation heat transfer when buildings are equipped with thermal piles. First, a numerical analysis of the thermal performance of thermo-active building foundations is developed and used to assess the interactions between thermal piles and slab-on-grade building foundations. The impact of various design parameters and operating conditions is evaluated including foundation pile depth, building slab width, foundation insulation configuration, and soil thermal properties. Based on the results of a series of parametric analyses, a simplified analysis method is presented to assess the impact of the thermal piles on the annual heat fluxes toward or from the building foundations. A comparative evaluation of the predictions of the simplified analysis method and those obtained from the detailed numerical analysis indicated good agreement with prediction accuracy lower than 5%. Moreover, it is found that thermal piles can affect annual building foundation heat loss/gain by up to 30% depending on foundation size and insulation level

Heat pipes and heat pipe exchangers for heat recovery systems

Energy Technology Data Exchange (ETDEWEB)

Vasiliev, L L; Grakovich, L P; Kiselev, V G; Kurustalev, D K; Matveev, Yu

1984-01-01

Heat pipes and heat pipe exchangers are of great importance in power engineering as a means of recovering waste heat of industrial enterprises, solar energy, geothermal waters and deep soil. Heat pipes are highly effective heat transfer units for transferring thermal energy over large distance (tens of meters) with low temperature drops. Their heat transfer characteristics and reliable working for more than 10-15 yr permit the design of new systems with higher heat engineering parameters.

Radiant heat loss, an unexploited path for heat stress reduction in shaded cattle.

Science.gov (United States)

Berman, A; Horovitz, T

2012-06-01

Reducing thermal radiation on shaded animals reduces heat stress independently of other means of stress relief. Radiant heat exchange was estimated as a function of climate, shade structure, and animal density. Body surface portion exposed to radiant sources in shaded environments was determined by geometrical relations to determine angles of view of radiation sources (roof underside, sky, sun-exposed ground, shaded ground) on the animal's surface. The relative representation of environment radiation sources on the body surface was determined. Animal thermal radiation balance was derived from radiant heat gained from radiation sources (including surrounding animals) and that lost from the animal surface. The animal environment was assumed to have different shade dimensions and temperatures. These were summed to the radiant heat balance of the cow. The data formed served to estimate the effect of changes in intensity of radiation sources, roof and shaded surface dimensions, and animal density on radiant heat balance (Rbal) of cattle. Roof height effect was expressed by effect of roof temperature on Rbal. Roof underside temperature (35 to 75°C) effect on Rbal was reduced by roof height. If roof height were 4m, an increase in its underside temperature from 35 to 75°C would increase mean Rbal from -63 to -2 W·m⁻², whereas if roof height were 10 m, Rbal would only increase from -99 to -88 W·m⁻². A hot ground temperature increase from 35 to 65°C reduced mean Rbal heat loss from -45 to 3 W·m⁻². Increasing the surface of the shaded area had only a minor effect on Rbal and on the effect of hot ground on Rbal. Increasing shade roof height reduced the effect of roof temperature on Rbal to minor levels when height was > 8m. Increasing the roof height from 4 to 10 m decreased Rbal from -32 to -94 W·m⁻². Increasing indirect radiation from 100 to 500 W·m⁻² was associated with an increase in Rbal from -135 to +23 W·m⁻². Their combined effects were lower

Analysis of the Potential of Low-Temperature Heat Pump Energy Sources

Directory of Open Access Journals (Sweden)

Pavel Neuberger

2017-11-01

Full Text Available The paper deals with an analysis of temperatures of ground masses in the proximities of linear and slinky-type HGHE (horizontal ground heat exchanger. It evaluates and compares the potentials of HGHEs and ambient air. The reason and aim of the verification was to gain knowledge of the temperature course of the monitored low-temperature heat pump energy sources during heating periods and periods of stagnation and to analyse the knowledge in terms of the potential to use those sources for heat pumps. The study was conducted in the years 2012–2015 during three heating periods and three periods of HGHEs stagnation. The results revealed that linear HGHE had the highest temperature potential of the observed low-temperature heat pump energy sources. The average daily temperatures of the ground mass surrounding the linear HGHE were the highest ranging from 7.08 °C to 9.20 °C during the heating periods, and having the lowest temperature variation range of 12.62–15.14 K, the relative frequency of the average daily temperatures of the ground mass being the highest at 22.64% in the temperature range containing the mode of all monitored temperatures in a recorded interval of [4.10, 6.00] °C. Ambient air had lower temperature potential than the monitored HGHEs.

Electric radiant heating or, why are plumbers getting our work?

Energy Technology Data Exchange (ETDEWEB)

Lemieux, G. [Britech, Toronto, ON (Canada)

2009-02-15

Electric radiant heating (ERH) technologies are now being installed in floors as a means of reducing heating costs. The radiant installations have seen a large increase in sales over the last decade, and are now being used in commercial applications. Sales of hydronic ERH systems have increased by 24 per cent over the last year. ERH systems are energy efficient and do not cause drafts. The systems consist of resistant heating cables installed within the floors of a room. The cables are supplied as loose cables and tracks with predetermined spacings or rugged, heavier cable that can be stapled onto wooden subfloors. Program temperature setbacks can be applied on a room-by-room basis. Electric thermal storage systems allow building owners to store heat in the floors and are ideal for use in combination with time-of-use electric metering. Some electric utilities are now promoting the use of electric thermal storage in order to reduce demand during peak times. Thermostats used with the systems should have floor sensors and ambient air sensors to control space heating in conjunction with the floor sensor. It was concluded that electrical contractors who gain knowledge in the application and installation of the systems will tap into a growing revenue stream. 5 figs.

Electric radiant heating or, why are plumbers getting our work?

International Nuclear Information System (INIS)

Lemieux, G.

2009-01-01

Electric radiant heating (ERH) technologies are now being installed in floors as a means of reducing heating costs. The radiant installations have seen a large increase in sales over the last decade, and are now being used in commercial applications. Sales of hydronic ERH systems have increased by 24 per cent over the last year. ERH systems are energy efficient and do not cause drafts. The systems consist of resistant heating cables installed within the floors of a room. The cables are supplied as loose cables and tracks with predetermined spacings or rugged, heavier cable that can be stapled onto wooden subfloors. Program temperature setbacks can be applied on a room-by-room basis. Electric thermal storage systems allow building owners to store heat in the floors and are ideal for use in combination with time-of-use electric metering. Some electric utilities are now promoting the use of electric thermal storage in order to reduce demand during peak times. Thermostats used with the systems should have floor sensors and ambient air sensors to control space heating in conjunction with the floor sensor. It was concluded that electrical contractors who gain knowledge in the application and installation of the systems will tap into a growing revenue stream. 5 figs

Heat pipes in modern heat exchangers

International Nuclear Information System (INIS)

Vasiliev, Leonard L.

2005-01-01

Heat pipes are very flexible systems with regard to effective thermal control. They can easily be implemented as heat exchangers inside sorption and vapour-compression heat pumps, refrigerators and other types of heat transfer devices. Their heat transfer coefficient in the evaporator and condenser zones is 10 3 -10 5 W/m 2 K, heat pipe thermal resistance is 0.01-0.03 K/W, therefore leading to smaller area and mass of heat exchangers. Miniature and micro heat pipes are welcomed for electronic components cooling and space two-phase thermal control systems. Loop heat pipes, pulsating heat pipes and sorption heat pipes are the novelty for modern heat exchangers. Heat pipe air preheaters are used in thermal power plants to preheat the secondary-primary air required for combustion of fuel in the boiler using the energy available in exhaust gases. Heat pipe solar collectors are promising for domestic use. This paper reviews mainly heat pipe developments in the Former Soviet Union Countries. Some new results obtained in USA and Europe are also included

Slug-flow dynamics with phase change heat transfer in compact heat exchangers with oblique wavy walls

Science.gov (United States)

Morimoto, Kenichi; Kinoshita, Hidenori; Matsushita, Ryo; Suzuki, Yuji

2017-11-01

With abundance of low-temperature geothermal energy source, small-scale binary-cycle power generation system has gained renewed attention. Although heat exchangers play a dominant role in thermal efficiency and the system size, the optimum design strategy has not been established due to complex flow phenomena and the lack of versatile heat transfer models. In the present study, the concept of oblique wavy walls, with which high j/f factor is achieved by strong secondary flows in single-phase system, is extended to two-phase exchangers. The present analyses are based on evaporation model coupled to a VOF technique, and a train of isolated bubbles is generated under the controlled inlet quality. R245fa is adopted as a low boiling-point working media, and two types of channels are considered with a hydraulic diameter of 4 mm: (i) a straight circular pipe and (ii) a duct with oblique wavy walls. The focus is on slug-flow dynamics with evaporation under small capillary but moderate Weber numbers, where the inertial effect as well as the surface tension is of significance. A possible direction of the change in thermo-physical properties is explored by assuming varied thermal conductivity. Effects of the vortical motions on evaporative heat transfer are highlighted. This work has been supported by the New Energy and Industrial Technology Development Organization (NEDO), Japan.

Numerical Investigation of the Fully-Developed Periodic Flow Field for Optimal Heat Transfer in Spirally Corrugated Tubes

DEFF Research Database (Denmark)

Hærvig, Jakob; Condra, Thomas Joseph; Sørensen, Kim

Even though the corrugated tube is a widely used technique to enhance transfer heat, the exact heat transfer enhancing mechanism remains relatively un-documented. Most studies attribute the favourable heat transfer characteristics to a swirling flow being present at higher corrugation....... In this study, a systematic approach relying on Computational Fluid Dynamics (CFD) is used to study and compare the heat transfer characteristics with the detailed flow field in the spirally corrugated tubes. By comparing the flow in 12 different spirally corrugated tubes at a fixed Reynolds number of 5000......, this study compares the flow field with the surface averaged Nusselt number to gain valuable insight into which flow phenomena causes favourable heat transfer characteristics. While the flow at low corrugations approximates the non-corrugated tube, higher corrugations of h/D creates a significant tangential...

Spontaneous indices are inconsistent with arterial baroreflex gain.

Science.gov (United States)

Lipman, Ruth D; Salisbury, Julie K; Taylor, J Andrew

2003-10-01

Spontaneously occurring, parallel fluctuations in arterial pressure and heart period are frequently used as indices of baroreflex function. Despite the convenience of spontaneous indices, their relation to the arterial baroreflex remains unclear. Therefore, in 97 volunteers, we derived 5 proposed indices (sequence method, alpha-index, transfer function, low-frequency transfer function, and impulse response function), compared them with arterial baroreflex gain (by the modified Oxford pharmacologic technique), and examined their relation to carotid distensibility and respiratory sinus arrhythmia. The subjects comprised men and women (n=41) aged 25 to 86 years, 30% of whom had established coronary artery disease. Generally, the indices were correlated with each other (except alpha-index and low-frequency transfer function) and with baroreflex gain. However, the Bland-Altman method demonstrated that the spontaneous indices had limits of agreement as large as the baroreflex gain itself. Even in individuals within the lowest tertile of baroreflex gain for whom baroreflex gain appears to be the most clinically relevant, spontaneous indices failed to relate to baroreflex gain. In fact, for these individuals, there was no correlation between any index and baroreflex gain. Forward stepwise linear regression showed that all spontaneous indices and baroreflex gain were related to respiratory sinus arrhythmia, but only baroreflex gain was related to carotid distensibility. Therefore, these data suggest that spontaneous indices are inadequate estimates of gain and are inconsistent with arterial baroreflex function.

Fitness-related differences in the rate of whole-body evaporative heat loss in exercising men are heat-load dependent.

Science.gov (United States)

Lamarche, Dallon T; Notley, Sean R; Louie, Jeffrey C; Poirier, Martin P; Kenny, Glen P

2018-01-01

What is the central question of this study? Aerobic fitness modulates heat loss, but the heat-load threshold at which fitness-related differences in heat loss occur in young healthy men remains unclear. What is the main finding and its importance? We demonstrate using direct calorimetry that aerobic fitness modulates heat loss in a heat-load-dependent manner, with fitness-related differences occurring between young men who have low and high fitness when the heat load is ∼≥500 W. Although aerobic fitness has been known for some time to modulate heat loss, our findings define the precise heat-load threshold at which fitness-related differences occur. The effect of aerobic fitness (defined as rate of peak oxygen consumption) on heat loss during exercise is thought to be related to the level of heat stress. However, it remains unclear at what combined exercise and environmental (net) heat-load threshold these fitness-related differences occur. To identify this, we assessed whole-body heat exchange (dry and evaporative) by direct calorimetry in young (22 ± 3 years) men matched for physical characteristics with low (Low-fit; 39.8 ± 2.5 ml O 2  kg -1  min -1 ), moderate (Mod-fit; 50.9 ± 1.2 ml O 2  kg -1  min -1 ) and high aerobic fitness (High-fit; 62.0 ± 4.4 ml O 2  kg -1  min -1 ; each n = 8), during three 30 min bouts of cycling in dry heat (40°C, 12% relative humidity) at increasing rates of metabolic heat production of 300 (Ex1), 400 (Ex2) and 500 W (Ex3), each followed by a 15 min recovery period. Each group was exposed to a similar net heat load (metabolic plus ∼100 W dry heat gain; P = 0.83) during each exercise bout [∼400 (Ex1), ∼500 (Ex2) and ∼600 W (Ex3); P fit (Ex2, 466 ± 21 W; Ex3, 557 ± 26 W) compared with the Low-fit group (Ex2, 439 ± 22 W; Ex3, 511 ± 20 W) during Ex2 and Ex3 (P ≤ 0.03). Conversely, evaporative heat loss for the Mod-fit group did not differ from either the High-fit or Low

Insulin detemir attenuates food intake, body weight gain and fat mass gain in diet-induced obese Sprague-Dawley rats.

Science.gov (United States)

Rojas, J M; Printz, R L; Niswender, K D

2011-07-04

Initiation and intensification of insulin therapy commonly causes weight gain, a barrier to therapy. A contrasting body of evidence indicates that insulin functions as an adiposity negative feedback signal and reduces food intake, weight gain and adiposity via action in the central nervous system. Basal insulin analogs, detemir (Det) and glargine (Glar), have been associated with less hypoglycemia compared with neutral protamine hagedorn insulin, and Det with less weight gain, especially in patients with higher body mass index (BMI). We sought to determine whether insulin therapy per se causes body weight and fat mass gain when delivered via a clinically relevant subcutaneous (SC) route in the absence of hypoglycemia and glycosuria in non-diabetic lean and diet-induced obese rats. Rats were exposed to either a low-fat diet (LFD; 13.5% fat) or high-fat diet (HFD; 60% fat), and received Det (0.5 U kg(-1)), Glar (0.2 U kg(-1)) or vehicle (Veh) SC once daily for 4 weeks. These dosages of insulin were equipotent in rats with respect to blood-glucose concentration and did not induce hypoglycemia. As predicted by current models of energy homeostasis, neither insulin Det nor Glar therapy affected food intake and weight gain in LFD rats. Det treatment significantly attenuated food intake, body weight gain and fat mass gain relative to the Glar and Veh in high-fat fed animals, mirroring observations in humans. That neither insulin group gained excess weight, suggests weight gain with SC basal insulin therapy may not be inevitable. Our data further suggest that Det possesses a unique property to attenuate the development of obesity associated with a HFD.

Multifamily Heat Pump Water Heater Evaluation

Energy Technology Data Exchange (ETDEWEB)

Hoeschele, M. [Alliance for Residential Building Innovation (ARBI), Davis, CA (United States); Weitzel, E. [Alliance for Residential Building Innovation (ARBI), Davis, CA (United States)

2013-11-22

Although heat pump water heaters (HPWHs) have gained significant attention in recent years as a high efficiency electric water heating solution for single family homes, central HPWHs for commercial or multi-family applications are not as well documented in terms of measured performance and cost effectiveness. To evaluate this technology, the Alliance for Residential Building Innovation team monitored the performance of a 10.5 ton central HPWH installed on a student apartment building at the West Village Zero Net Energy Community in Davis, California. Monitoring data collected over a 16 month period were then used to validate a TRNSYS simulation model. The TRNSYS model was then used to project performance in different climates using local electric rates. Results of the study indicate that after some initial commissioning issues, the HPWH operated reliably with an annual average efficiency of 2.12 (Coefficient of Performance). The observed efficiency was lower than the unit's rated efficiency, primarily due to the fact that the system rarely operated under steady-state conditions. Changes in the system configuration, storage tank sizing, and control settings would likely improve the observed field efficiency. Modeling results suggest significant energy savings relative to electric storage water heating systems (typical annual efficiencies around 0.90) providing for typical simple paybacks of six to ten years without any incentives. The economics versus gas water heating are currently much more challenging given the current low natural gas prices in much of the country. Increased market size for this technology would benefit cost effectiveness and spur greater technology innovation.

Multifamily Heat Pump Water Heater Evaluation

Energy Technology Data Exchange (ETDEWEB)

Hoeschele, M. [Davis Energy Group, Davis, CA (United States). Alliance for Residential Building Innovation; Weitzel, E. [Davis Energy Group, Davis, CA (United States). Alliance for Residential Building Innovation

2017-03-03

Although heat pump water heaters (HPWHs) have gained significant attention in recent years as a high efficiency electric water heating solution for single family homes, central HPWHs for commercial or multi-family applications are not as well documented in terms of measured performance and cost effectiveness. To evaluate this technology, the Alliance for Residential Building Innovation team monitored the performance of a 10.5 ton central HPWH installed on a student apartment building at the West Village Zero Net Energy Community in Davis, California. Monitoring data collected over a 16 month period were then used to validate a TRNSYS simulation model. The TRNSYS model was then used to project performance in different climates using local electric rates. Results of the study indicate that after some initial commissioning issues, the HPWH operated reliably with an annual average efficiency of 2.12 (Coefficient of Performance). The observed efficiency was lower than the unit's rated efficiency, primarily due to the fact that the system rarely operated under steady-state conditions. Changes in the system configuration, storage tank sizing, and control settings would likely improve the observed field efficiency. Modeling results suggest significant energy savings relative to electric storage water heating systems (typical annual efficiencies around 0.90) providing for typical simple paybacks of six to ten years without any incentives. The economics versus gas water heating are currently much more challenging given the current low natural gas prices in much of the country. Increased market size for this technology would benefit cost effectiveness and spur greater technology innovation.

Multifamily Heat Pump Water Heater Evaluation

Energy Technology Data Exchange (ETDEWEB)

Hoeschele, M. [Alliance for Residential Building Innovation (ARBI), Davis, CA (United States); Weitzel, E. [Alliance for Residential Building Innovation (ARBI), Davis, CA (United States)

2017-03-01

Although heat pump water heaters (HPWHs) have gained significant attention in recent years as a high efficiency electric water heating solution for single family homes, central HPWHs for commercial or multi-family applications are not as well documented in terms of measured performance and cost effectiveness. To evaluate this technology, the Alliance for Residential Building Innovation team monitored the performance of a 10.5 ton central HPWH installed on a student apartment building at the West Village Zero Net Energy Community in Davis, California. Monitoring data collected over a 16 month period were then used to validate a TRNSYS simulation model. The TRNSYS model was then used to project performance in different climates using local electric rates. Results of the study indicate that after some initial commissioning issues, the HPWH operated reliably with an annual average efficiency of 2.12 (Coefficient of Performance). The observed efficiency was lower than the unit's rated efficiency, primarily due to the fact that the system rarely operated under steady-state conditions. Changes in the system configuration, storage tank sizing, and control settings would likely improve the observed field efficiency. Modeling results suggest significant energy savings relative to electric storage water heating systems (typical annual efficiencies around 0.90) providing for typical simple paybacks of six to ten years without any incentives. The economics versus gas water heating are currently much more challenging given the current low natural gas prices in much of the country. Increased market size for this technology would benefit cost effectiveness and spur greater technology innovation.

Thermoelectric Power Generation Utilizing the Waste Heat from a Biomass Boiler

Science.gov (United States)

Brazdil, Marian; Pospisil, Jiri

2013-07-01

The objective of the presented work is to test the possibility of using thermoelectric power to convert flue gas waste heat from a small-scale domestic pellet boiler, and to assess the influence of a thermoelectric generator on its function. A prototype of the generator, able to be connected to an existing device, was designed, constructed, and tested. The performance of the generator as well as the impact of the generator on the operation of the boiler was investigated under various operating conditions. The boiler gained auxiliary power and could become a combined heat and power unit allowing self-sufficient operation. The created unit represents an independent source of electricity with effective use of fuel.

High average power CW FELs [Free Electron Laser] for application to plasma heating: Designs and experiments

International Nuclear Information System (INIS)

Booske, J.H.; Granatstein, V.L.; Radack, D.J.; Antonsen, T.M. Jr.; Bidwell, S.; Carmel, Y.; Destler, W.W.; Latham, P.E.; Levush, B.; Mayergoyz, I.D.; Zhang, Z.X.

1989-01-01

A short period wiggler (period ∼ 1 cm), sheet beam FEL has been proposed as a low-cost source of high average power (1 MW) millimeter-wave radiation for plasma heating and space-based radar applications. Recent calculation and experiments have confirmed the feasibility of this concept in such critical areas as rf wall heating, intercepted beam (''body'') current, and high voltage (0.5 - 1 MV) sheet beam generation and propagation. Results of preliminary low-gain sheet beam FEL oscillator experiments using a field emission diode and pulse line accelerator have verified that lasing occurs at the predicted FEL frequency. Measured start oscillation currents also appear consistent with theoretical estimates. Finally, we consider the possibilities of using a short-period, superconducting planar wiggler for improved beam confinement, as well as access to the high gain, strong pump Compton regime with its potential for highly efficient FEL operation

Implosion scaling and hydro dynamically equivalent target design - Strategy for proof of principle of high gain inertial fusion

International Nuclear Information System (INIS)

Murakami, M.; Nishihara, K.; Azechi, H.; Nakatsuka, M.; Kanabe, T.; Miyanaga, N.

2003-01-01

Scaling laws for hydro dynamically similar implosions are derived by applying Lie group analysis to the set of partial differential equations for the hydrodynamic system. Physically this implies that any fluid system belonging to a common similarity group evolves quite in the same manner including hydrodynamic instabilities. The scalings strongly depend on the description of the energy transport, i.e., whether the fluid system is heat conductive or adiabatic. Under a fully specified group transformation including prescriptions on the laser wavelength and the ionization state, the hydrodynamic similarity can still be preserved even when the system is cooperated with such other energy sources as classical laser absorption, hot electrons, local alpha heating, and bremsstrahlung loss. The results are expected to give the basis of target design and diagnostics for scaled high gain experiments in future. (author)

Heat pumps: heat recovery

Energy Technology Data Exchange (ETDEWEB)

Pielke, R

1976-01-01

The author firstly explains in a general manner the functioning of the heat pump. Following a brief look at the future heat demand and the possibilities of covering it, the various methods of obtaining energy (making use of solar energy, ground heat, and others) and the practical applications (office heating, swimming pool heating etc.) are explained. The author still sees considerable difficulties in using the heat pump at present on a large scale. Firstly there is not enough maintenance personnel available, secondly the electricity supply undertakings cannot provide the necessary electricity on a wide basis without considerable investments. Other possibilities to save energy or to use waste energy are at present easier and more economical to realize. Recuperative and regenerative systems are described.

Mitigation of Short-Lived Climate Pollutants from Residential Coal Heating and Combined Heating/Cooking Stoves: Impacts on the Cryosphere, Policy Options, and Co-benefits

Science.gov (United States)

Chafe, Z.; Anenberg, S.; Klimont, Z.; Kupiainen, K.; Lewis, J.; Metcalfe, J.; Pearson, P.

2017-12-01

Residential solid fuel combustion for cooking, heating, and other energy services contributes to indoor and outdoor air pollution, and creates impacts on the cryosphere. Solid fuel use often occurs in colder climates and at higher elevations, where a wide range of combustion emissions can reduce reflectivity of the snow- and ice-covered surfaces, causing climatic warming. Reducing short-lived climate pollutants (SLCPs), such as black carbon (BC), could have substantial climate and health co-benefits, especially in areas where emissions influence the cryosphere. A review of existing literature and emissions estimates, conducted as part of the Warsaw Summit on BC and Other Emissions from Residential Coal Heating Stoves and Combined Cooking/Heating Stoves, found little nationally-representative data on the fuels and technologies used for heating and combined cooking/heating. The GAINS model estimates that 24 million tonnes of coal equivalent were combusted by households for space heating globally in 2010, releasing 190 kilotons (kt) BC. Emissions from combined cooking/heating are virtually unknown. Policy instruments could mitigate cryosphere-relevant emissions of SLCPs from residential heating or cooking. These include indoor air quality guidelines, stove emission limits, bans on the use of specific fuels, regulatory codes that stipulate when burning can occur, stove changeout programs, and voluntary public education campaigns. These measures are being implemented in countries such as Chile (fuelwood moisture reduction campaign, energy efficiency, heating system improvements), Mongolia (stove renovation, fuel switching), Peru (improved stove programs), Poland (district heating, local fuel bans), United States (stove emission regulation) and throughout the European Community (Ecodesign Directive). Few, if any, of these regulations are likely to reduce emissions from combined cooking/heating. This research team found no global platform to create and share model

The effect of holiday weight gain on body weight.

Science.gov (United States)

Schoeller, Dale A

2014-07-01

The topic of holiday weight gain has been a frequent subject of the lay media; however, scientific interest has only been recent. Multiple studies in Western societies have reported average weight gains among adults during the period between mid-November and mid-January that were about 0.5 kg. The range in individual weight changes was large, however, and the already overweight and obese gain more weight than those who are healthy weight. When the average gain across the year was also measured, the holiday weight was the major contributor to annual excess weight gain. Efforts patterned to increase awareness to energy balance and body weight have been shown to be successful at reducing such gain. An exception to holiday weight gain being a major contributor to annual excess gain has been children, in whom summer weight gains have been observed to be the major contributor to average excess weight gain. Copyright © 2014 Elsevier Inc. All rights reserved.

Bayesian inference of the heat transfer properties of a wall using experimental data

KAUST Repository

Iglesias, Marco

2016-01-06

A hierarchical Bayesian inference method is developed to estimate the thermal resistance and volumetric heat capacity of a wall. We apply our methodology to a real case study where measurements are recorded each minute from two temperature probes and two heat flux sensors placed on both sides of a solid brick wall along a period of almost five days. We model the heat transfer through the wall by means of the one-dimensional heat equation with Dirichlet boundary conditions. The initial/boundary conditions for the temperature are approximated by piecewise linear functions. We assume that temperature and heat flux measurements have independent Gaussian noise and derive the joint likelihood of the wall parameters and the initial/boundary conditions. Under the model assumptions, the boundary conditions are marginalized analytically from the joint likelihood. ApproximatedGaussian posterior distributions for the wall parameters and the initial condition parameter are obtained using the Laplace method, after incorporating the available prior information. The information gain is estimated under different experimental setups, to determine the best allocation of resources.

Optimized Design of Thermoelectric Energy Harvesting Systems for Waste Heat Recovery from Exhaust Pipes

Directory of Open Access Journals (Sweden)

Marco Nesarajah

2017-06-01

Full Text Available With the increasing interest in energy efficiency and resource protection, waste heat recovery processes have gained importance. Thereby, one possibility is the conversion of the heat energy into electrical energy by thermoelectric generators. Here, a thermoelectric energy harvesting system is developed to convert the waste heat from exhaust pipes, which are very often used to transport the heat, e.g., in automobiles, in industrial facilities or in heating systems. That is why a mockup of a heating is built-up, and the developed energy harvesting system is attached. To build-up this system, a model-based development process is used. The setup of the developed energy harvesting system is very flexible to test different variants and an optimized system can be found in order to increase the energy yield for concrete application examples. A corresponding simulation model is also presented, based on previously developed libraries in Modelica®/Dymola®. In the end, it can be shown—with measurement and simulation results—that a thermoelectric energy harvesting system on the exhaust pipe of a heating system delivers extra energy and thus delivers a contribution for a more efficient usage of the inserted primary energy carrier.

Spectral hole-burning and carrier-heating dynamics in InGaAs quantum-dot amplifiers

DEFF Research Database (Denmark)

Borri, Paola; Langbein, Wolfgang Werner; Hvam, Jørn Märcher

2000-01-01

recovery of the spectral hole within ~100 fs is measured, comparable to bulk and quantum-well amplifiers, which is contradicting a carrier relaxation bottleneck in electrically pumped QD devices. The CH dynamics in the QD is quantitatively compared with results on an InGaAsP bulk amplifier. Reduced CH......The ultrafast gain and index dynamics in a set of InAs-InGaAs-GaAs quantum-dot (QD) amplifiers are measured at room temperature with femtosecond resolution. The role of spectral hole-burning (SHB) and carrier heating (CH) in the recovery of gain compression is investigated in detail. An ultrafast...

Improvement of Reactor Fuel Element Heat Transfer by Surface Roughness

Energy Technology Data Exchange (ETDEWEB)

Kjellstroem, B; Larsson, A E

1967-04-15

In heat exchangers with a limited surface temperature such as reactor fuel elements, rough heat transfer surfaces may give lower pumping power than smooth. To obtain data for choice of the most advantageous roughness for the superheater elements in the Marviken reactor, measurements were made of heat transfer and pressure drop in an annular channel with a smooth or rough test rod in a smooth adiabatic shroud. 24 different roughness geometries were tested. The results were transformed to rod cluster geometry by the method of W B Hall, and correlated by the friction and heat transfer similarity laws as suggested by D F Dipprey and R H Sabersky with RMS errors of 12.5 % in the friction factor and 8.1 % in the Stanton number. The relation between the Stanton number and the friction factor could be described by a relation of the type suggested by W Nunner, with a mean error of 3.1 % and an RMS error of 11.6 %. Application of the results to fuel element calculations is discussed, and the great gains in economy which can be obtained with rough surfaces are demonstrated by two examples.

Improvement of Reactor Fuel Element Heat Transfer by Surface Roughness

International Nuclear Information System (INIS)

Kjellstroem, B.; Larsson, A.E.

1967-04-01

In heat exchangers with a limited surface temperature such as reactor fuel elements, rough heat transfer surfaces may give lower pumping power than smooth. To obtain data for choice of the most advantageous roughness for the superheater elements in the Marviken reactor, measurements were made of heat transfer and pressure drop in an annular channel with a smooth or rough test rod in a smooth adiabatic shroud. 24 different roughness geometries were tested. The results were transformed to rod cluster geometry by the method of W B Hall, and correlated by the friction and heat transfer similarity laws as suggested by D F Dipprey and R H Sabersky with RMS errors of 12.5 % in the friction factor and 8.1 % in the Stanton number. The relation between the Stanton number and the friction factor could be described by a relation of the type suggested by W Nunner, with a mean error of 3.1 % and an RMS error of 11.6 %. Application of the results to fuel element calculations is discussed, and the great gains in economy which can be obtained with rough surfaces are demonstrated by two examples

Personality type influence the gestational weight gain.

Science.gov (United States)

Franik, Grzegorz; Lipka, Nela; Kopyto, Katarzyna; Kopocińska, Joanna; Owczarek, Aleksander; Sikora, Jerzy; Madej, Paweł; Chudek, Jerzy; Olszanecka-Glinianowicz, Magdalena

2017-08-01

Pregnancy is frequently followed by the development of obesity. Aside from psychological factors, hormonal changes influence weight gain in pregnant women. We attempted to assess the potential association between personality type and the extent of gestational weight gain. The study group involved 773 women after term delivery (age 26.3 ± 3.9 years, body mass before pregnancy 61.2 ± 11.1 kg). Weight gain during pregnancy was calculated by using self-reported body mass prior to and during the 38th week of pregnancy. Personality type was assessed using the Polish version of the Framingham Type A Behavior Patterns Questionnaire (adapted by Juczynski). Two hundred forty-six (31.8%) study subjects represented type A personalities, 272 (35.2%) type B and 255 (33.0%) an indirect type. Gestational weight gain was related to the behavior patterns questionnaire score and age. In women gain was higher than in women with type B behavior of the same age. In women >30, the gestational weight gain was larger for type B personalities. Type A personality and increased urgency in younger pregnant women increases the risk of developing obesity during pregnancy in women below 30 years old. A higher level of competitiveness demonstrates a risk factor of excessive weight gain during pregnancy regardless of age.

Intrinsic gain modulation and adaptive neural coding.

Directory of Open Access Journals (Sweden)

Sungho Hong

2008-07-01

Full Text Available In many cases, the computation of a neural system can be reduced to a receptive field, or a set of linear filters, and a thresholding function, or gain curve, which determines the firing probability; this is known as a linear/nonlinear model. In some forms of sensory adaptation, these linear filters and gain curve adjust very rapidly to changes in the variance of a randomly varying driving input. An apparently similar but previously unrelated issue is the observation of gain control by background noise in cortical neurons: the slope of the firing rate versus current (f-I curve changes with the variance of background random input. Here, we show a direct correspondence between these two observations by relating variance-dependent changes in the gain of f-I curves to characteristics of the changing empirical linear/nonlinear model obtained by sampling. In the case that the underlying system is fixed, we derive relationships relating the change of the gain with respect to both mean and variance with the receptive fields derived from reverse correlation on a white noise stimulus. Using two conductance-based model neurons that display distinct gain modulation properties through a simple change in parameters, we show that coding properties of both these models quantitatively satisfy the predicted relationships. Our results describe how both variance-dependent gain modulation and adaptive neural computation result from intrinsic nonlinearity.

E-beam heated linear solenoid reactors

International Nuclear Information System (INIS)

Benford, J.; Bailey, V.; Oliver, D.

1976-01-01

A conceptual design and system analysis shows that electron beam heated linear solenoidal reactors are attractive for near term applications which can use low gain fusion sources. Complete plant designs have been generated for fusion based breeders of fissile fuel over a wide range of component parameters (e.g., magnetic fields, reactor lengths, plasma densities) and design options (e.g., various radial and axial loss mechanisms). It appears possible that a reactor of 100 to 300 meters length operating at power levels of 1000 MWt can economically produce 2000 to 8000 kg/yr of 233 U to supply light water reactor fuel needs beyond 2000 A.D. Pure fusion reactors of 300 to 500 meter lengths are possible. Physics and operational features of reactors are described. Beam heating by classical and anomalous energy deposition is reviewed. The technology of the required beams has been developed to MJ/pulse levels, within a factor of 20 of that needed for full scale production reactors. The required repetitive pulsing appears practical

IQ Gains in Argentina between 1964 and 1998

Science.gov (United States)

Flynn, James R.; Rossi-Case, Lilia

2012-01-01

The literature on IQ gains in Latin America is sparse. We estimate gains on Raven's Progressive Matrices in the city of La Plata (Argentina) between 1964 and 1998. The gains are robust at the top of the curve as well as at the bottom. Therefore, they are contrary to the hypothesis that nutrition played a major role in recent Argentine IQ gains.…

Wood chip drying in connection with combined heat and power or solar energy in Finland

Directory of Open Access Journals (Sweden)

Rinne Samuli

2014-01-01

Full Text Available 20% of the Finnish district heating (DH power plant fuels are wood-based and the share is increasing. The wood fuel demand probably exceeds the potential supply in the future. The wood fuel drying with waste heat is one profitable opportunity to gain more wood fuel. If the drying energy can be produced with lower primary energy use than combusting the fuel directly, the drying potentially improves the system efficiency. In this study, the drying feasibility in the connection of a combined heat and power (CHP system, possibly with solar collectors, is calculated. The wood fuel heating can be increased profitably by 6%, using the heat from CHP for drying only when the marginal cost of the heat is low enough, i.e. the electricity price is high enough and there is free capacity after the DH demand. Although the drying is profitable, a larger heat storage can also increase the annual result similarly. The best investment choice depends on the plant properties. Here the optimal system enables 20% DH production cost savings. Solar heat may be profitable, when the solar heat has a 2–3% share of the annual heat demand. However, the dryer or larger storage tank are more profitable investments.

Loss restlessness and gain calmness: durable effects of losses and gains on choice switching.

Science.gov (United States)

Yechiam, Eldad; Zahavi, Gal; Arditi, Eli

2015-08-01

While the traditional conceptualization of the effect of losses focuses on bias in the subjective weight of losses compared with respective gains, some accounts suggest more global task-related effects of losses. Based on a recent attentional theory, we predicted a positive after-effect of losses on choice switching in later tasks. In two experimental studies, we found increased choice switching rates in tasks with losses compared to tasks with no losses. Additionally, this heightened shifting behavior was maintained in subsequent tasks that do not include losses, a phenomenon we refer to as "loss restlessness." Conversely, gains were found to have an opposite "calming" effect on choice switching. Surprisingly, the loss restlessness phenomenon was observed following an all-losses payoff regime but not after a task with symmetric mixed gains and losses. This suggests that the unresolved mental account following an all-losses regime increases search behavior. Potential implications to macro level phenomena, such as the leverage effect, are discussed.

Energy balance of droplets impinging onto a wall heated above the Leidenfrost temperature

International Nuclear Information System (INIS)

Dunand, P.; Castanet, G.; Gradeck, M.; Maillet, D.; Lemoine, F.

2013-01-01

Highlights: • Measurement techniques are combined to characterize the heat lost due to liquid vaporization. • The wall heat flux is estimated by infrared thermography associated with inverse heat conduction. • The liquid heating is characterized by the two-color Laser-Induced Fluorescence thermometry. • Results reveal how the heat fluxes vary with the droplet sizes and the Weber number. -- Abstract: This work is an experimental study aiming at characterizing the heat transfers induced by the impingement of water droplets (diameter 80–180 μm) on a thin nickel plate heated by electromagnetic induction. The temperature of the rear face of the nickel sample is measured by means of an infrared camera and the heat removed from the wall due to the presence of the droplets is estimated using a semi-analytical inverse heat conduction model. In parallel, the temperature of the droplets is measured using the two-color Laser-Induced Fluorescence thermometry (2cLIF) which has been extended to imagery for the purpose of these experiments. The measurements of the variation in the droplet temperature occurring during an impact allow determining the sensible heat removed by the liquid. Measurements are performed at wall conditions well above the Leidenfrost temperature. Different values of the Weber numbers corresponding to the bouncing and splashing regimes are tested. Comparisons between the heat flux removed from the wall and the sensible heat gained by the liquid allows estimating the heat flux related to liquid evaporation. Results reveal that the respective level of the droplet sensible heat and the heat lost due to liquid vaporization can vary significantly with the droplet sizes and the Weber number

Ladder Ising spin configurations. Pt. 1. Heat capacity

International Nuclear Information System (INIS)

Mejdani, R.; Lambros, A.

1996-01-01

We consider a ladder Ising spin model (with two coupled Ising spin chains), characterized by two couplings (interchain and intrachain couplings), to study in detail, in an analytical way, its thermal behaviour and particularly the variation of the specific heat versus temperature, the ratio of interaction constants, and the magnetic field. It is interesting that when the competition between interchain and intrachain interactions is strong the specific heat exhibits a double peak and when the competition is not so strong the specific heat has a single peak. Further, without entering into details, we give, in a numerical way, some similar results for more complicated ladder configurations (with more than two linear Ising chains). The spin-1/2 ladders or systems of spin chains may be realized in nature by vanadyl pyrophosphate ((VO) 2 P 2 O 7 ) or similar materials. All these intermediate systems are today important to gain further insight into the physics of one-dimensional spin chains and two-dimensional high-T c spin systems, both of which have shown interesting and unusual magnetic and superconducting properties. It is plausible that experimental and theoretical studies of ladders may lead to other interesting physical phenomena. (orig.)

New waste heat district heating system with combined heat and power based on absorption heat exchange cycle in China

International Nuclear Information System (INIS)

Sun Fangtian; Fu Lin; Zhang Shigang; Sun Jian

2012-01-01

A new waste heat district heating system with combined heat and power based on absorption heat exchange cycle (DHAC) was developed to increase the heating capacity of combined heat and power (CHP) through waste heat recovery, and enhance heat transmission capacity of the existing primary side district heating network through decreasing return water temperature by new type absorption heat exchanger (AHE). The DHAC system and a conventional district heating system based on CHP (CDH) were analyzed in terms of both thermodynamics and economics. Compared to CDH, the DHAC increased heating capacity by 31% and increased heat transmission capacity of the existing primary side district heating network by 75%. The results showed that the exergetic efficiency of DHAC was 10.41% higher and the product exergy monetary cost was 36.6¥/GJ less than a CHD. DHAC is an effective way to increase thermal utilization factor of CHP, and to reduce district heating cost. - Highlights: ► Absorption heat pumps are used to recover waste heat in CHP. ► Absorption heat exchanger can reduce exergy loss in the heat transfer process. ► New waste heat heating system (DHAC) can increase heating capacity of CHP by 31%. ► DHAC can enhance heat transmission capacity of the primary pipe network by 75%. ► DHAC system has the higher exergetic efficiency and the better economic benefit.

Heating systems for heating subsurface formations

Science.gov (United States)

Nguyen, Scott Vinh [Houston, TX; Vinegar, Harold J [Bellaire, TX

2011-04-26

Methods and systems for heating a subsurface formation are described herein. A heating system for a subsurface formation includes a sealed conduit positioned in an opening in the formation and a heat source. The sealed conduit includes a heat transfer fluid. The heat source provides heat to a portion of the sealed conduit to change phase of the heat transfer fluid from a liquid to a vapor. The vapor in the sealed conduit rises in the sealed conduit, condenses to transfer heat to the formation and returns to the conduit portion as a liquid.

Central gain control in tinnitus and hyperacusis

Directory of Open Access Journals (Sweden)

Benjamin D Auerbach

2014-10-01

Full Text Available Sensorineural hearing loss induced by noise or ototoxic drug exposure reduces the neural activity transmitted from the cochlea to the central auditory system. Despite a reduced cochlear output, neural activity from more central auditory structures is paradoxically enhanced at suprathreshold intensities. This compensatory increase in the central auditory activity in response to the loss of sensory input is referred to as central gain enhancement. Enhanced central gain is hypothesized to be a potential mechanism that gives rise to hyperacusis and tinnitus, two debilitating auditory perceptual disorders that afflict millions of individuals. This review will examine the evidence for gain enhancement in the central auditory system in response to cochlear damage. Further, it will address the potential cellular and molecular mechanisms underlying this enhancement and discuss the contribution of central gain enhancement to tinnitus and hyperacusis. Current evidence suggests that multiple mechanisms with distinct temporal and spectral profiles are likely to contribute to central gain enhancement. Dissecting the contributions of these different mechanisms at different levels of the central auditory system is essential for elucidating the role of central gain enhancement in tinnitus and hyperacusis and, most importantly, the development of novel treatments for these disorders.

Central Gain Control in Tinnitus and Hyperacusis

Science.gov (United States)

Auerbach, Benjamin D.; Rodrigues, Paulo V.; Salvi, Richard J.

2014-01-01

Sensorineural hearing loss induced by noise or ototoxic drug exposure reduces the neural activity transmitted from the cochlea to the central auditory system. Despite a reduced cochlear output, neural activity from more central auditory structures is paradoxically enhanced at suprathreshold intensities. This compensatory increase in the central auditory activity in response to the loss of sensory input is referred to as central gain enhancement. Enhanced central gain is hypothesized to be a potential mechanism that gives rise to hyperacusis and tinnitus, two debilitating auditory perceptual disorders that afflict millions of individuals. This review will examine the evidence for gain enhancement in the central auditory system in response to cochlear damage. Further, it will address the potential cellular and molecular mechanisms underlying this enhancement and discuss the contribution of central gain enhancement to tinnitus and hyperacusis. Current evidence suggests that multiple mechanisms with distinct temporal and spectral profiles are likely to contribute to central gain enhancement. Dissecting the contributions of these different mechanisms at different levels of the central auditory system is essential for elucidating the role of central gain enhancement in tinnitus and hyperacusis and, most importantly, the development of novel treatments for these disorders. PMID:25386157

Effect of heat exposure on gene expression of feed intake regulatory peptides in laying hens.

Science.gov (United States)

Song, Zhigang; Liu, Lei; Sheikhahmadi, Ardashir; Jiao, Hongchao; Lin, Hai

2012-01-01

The aim of this paper was to investigate the effect of heat stress on the regulation of appetite-associated genes in laying hens. Forty eight laying hens were randomly divided into two circumstances: high (31 ± 1.5°C; relative humidity, 82.0 ± 2.2%) or normal (20 ± 2°C, control; relative humidity, 60.1 ± 4.5%) ambient environment. Heat stress decreased body weight gain (P feed intake (P feed efficiency (P feed intake in laying hens under high ambient temperature.

Heat pipe heat exchanger for heat recovery in air conditioning

Energy Technology Data Exchange (ETDEWEB)

Abd El-Baky, Mostafa A.; Mohamed, Mousa M. [Mechanical Power Engineering Department, Faculty of Engineering, Minufiya University, Shebin El-Kom (Egypt)

2007-03-15

The heat pipe heat exchangers are used in heat recovery applications to cool the incoming fresh air in air conditioning applications. Two streams of fresh and return air have been connected with heat pipe heat exchanger to investigate the thermal performance and effectiveness of heat recovery system. Ratios of mass flow rate between return and fresh air of 1, 1.5 and 2.3 have been adapted to validate the heat transfer and the temperature change of fresh air. Fresh air inlet temperature of 32-40{sup o}C has been controlled, while the inlet return air temperature is kept constant at about 26{sup o}C. The results showed that the temperature changes of fresh and return air are increased with the increase of inlet temperature of fresh air. The effectiveness and heat transfer for both evaporator and condenser sections are also increased to about 48%, when the inlet fresh air temperature is increased to 40{sup o}C. The effect of mass flow rate ratio on effectiveness is positive for evaporator side and negative for condenser side. The enthalpy ratio between the heat recovery and conventional air mixing is increased to about 85% with increasing fresh air inlet temperature. The optimum effectiveness of heat pipe heat exchanger is estimated and compared with the present experimental data. The results showed that the effectiveness is close to the optimum effectiveness at fresh air inlet temperature near the fluid operating temperature of heat pipes. (author)

Measured stimulated Raman gain in methane

International Nuclear Information System (INIS)

Lopert, R.B.

1983-01-01

This report is about the stimulated Raman effect in methane due to the nu 1 vibration. For various gas pressures between 150 torr and 30 atm, the Raman lineshape function was both experimentally measured and synthesized using a computer model. The stimulated Raman gain was measured by sending a pump laser beam provided by an argon-ion laser and a weak probe beam provided by a tunable dye laser through a cell of methane gas. The stimulated Raman effect caused some of the energy from the pump beam to be transferred to the probe beam. The intensity of the pump beam was low so the gain of the probe beam was on the order of parts per million. A two detector arrangement and a differential amplifier system that had a feedback loop to balance the detectors was constructed to measure the small gains. A detailed description of this detection system that was able to measure gains as small as 0.2 parts per million is provided

Thermoregulatory efficiency is increased after heat acclimation in tropical natives.

Science.gov (United States)

Magalhães, Flávio C; Passos, Renata L F; Fonseca, Michele A; Oliveira, Kenya P M; Ferreira-Júnior, João B; Martini, Angelo R P; Lima, Milene R M; Guimarães, Juliana B; Baraúna, Valério G; Silami-Garcia, Emerson; Rodrigues, Luiz O C

2010-01-01

To evaluate the effects of heat acclimation on sweat rate redistribution and thermodynamic parameters, 9 tropical native volunteers were submitted to 11 days of exercise-heat exposures (40+/-0 degrees C and 45.1+/-0.2% relative humidity). Sudomotor function was evaluated by measuring total and local (forehead, chest, arm, forearm, and thigh) sweat rates, local sweat sodium concentration, and mean skin and rectal temperatures. We also calculated heat production (H), heat storage (S), heat exchange by radiation (R) and by convection (C), evaporated sweat (E(sw)), sweating efficiency (eta(sw)), skin wettedness (w(sk)), and the ratio between the heat storage and the sum of heat production and heat gains by radiation and convection (S/(H+R+C)). The heat acclimation increased the whole-body sweat rate and reduced the mean skin temperature. There were changes in the local sweat rate patterns: on the arm, forearm, and thigh it increased significantly from day 1 to day 11 (all p<0.05) and the sweat rates from the forehead and the chest showed a small nonsignificant increase (p=0.34 and 0.17, respectively). The relative increase of local sweat rates on day 11 was not different among the sites; however, when comparing the limbs (arm, forearm, and thigh) with the trunk (forehead and chest), there was a significant higher increase in the limbs (32+/-5%) in comparison to the trunk (11+/-2%, p=0.001). After the heat acclimation period we observed higher w(sk) and E(sw) and reduced S/(H+R+C), meaning greater thermoregulatory efficiency. The increase in the limb sweat rate, but not the increase in the trunk sweat rate, correlated with the increased w(sk), E(sw), and reduced S/(H+R+C) (p<0.05 to all). Altogether, it can be concluded that heat acclimation increased the limbs' sweat rates in tropical natives and that this increase led to increased loss of heat through evaporation of sweat and this higher sweat evaporation was related to higher thermoregulatory efficiency.

Influence of heat treatment on the high temperature oxidation mechanisms of an Fe-TiCN cermet

OpenAIRE

Alvaredo Olmos, Paula; Abajo Clemente, Carolina; Tsipas, Sophia Alexandra; Gordo Odériz, Elena

2014-01-01

In this study, the oxidation behaviour of an iron matrix cermet containing 50 % vol. Ti(C,N) was investigated before and after heat treatment by oxidation tests performed in static air at temperatures between 500 °C and 1000 °C. The oxidation mechanism for this type of composite materials was established and it was found that the heat treated material presents lower mass gain than the as-sintered material at the early stages of the oxidation, due to the volatilization of oxides. The oxidation...

Future heat supply of our cities. Heating by waste heat

Energy Technology Data Exchange (ETDEWEB)

Brachetti, H E [Stadtwerke Hannover A.G. (Germany, F.R.); Technische Univ. Hannover (Germany, F.R.))

1976-08-01

The energy-price crisis resulted in structural changes of the complete energy supply and reactivated the question of energy management with respect to the optimum solution of meeting the energy requirements for space heating. Condensation power plants are increasingly replaced by thermal stations, the waste heat of which is used as so-called district heat. Thermal power stations must be situated close to urban areas. The problem of emission of harmful materials can partly be overcome by high-level emission. The main subject of the article, however, is the problem of conducting and distributing the heat. The building costs of heat pipeline systems and the requirements to be met by heat pipelines such as strength, heat insulation and protection against humidity and ground water are investigated.

Radiation hardness of thin Low Gain Avalanche Detectors

Science.gov (United States)

Kramberger, G.; Carulla, M.; Cavallaro, E.; Cindro, V.; Flores, D.; Galloway, Z.; Grinstein, S.; Hidalgo, S.; Fadeyev, V.; Lange, J.; Mandić, I.; Medin, G.; Merlos, A.; McKinney-Martinez, F.; Mikuž, M.; Quirion, D.; Pellegrini, G.; Petek, M.; Sadrozinski, H. F.-W.; Seiden, A.; Zavrtanik, M.

2018-05-01

Low Gain Avalanche Detectors (LGAD) are based on a n++-p+-p-p++ structure where an appropriate doping of the multiplication layer (p+) leads to high enough electric fields for impact ionization. Gain factors of few tens in charge significantly improve the resolution of timing measurements, particularly for thin detectors, where the timing performance was shown to be limited by Landau fluctuations. The main obstacle for their operation is the decrease of gain with irradiation, attributed to effective acceptor removal in the gain layer. Sets of thin sensors were produced by two different producers on different substrates, with different gain layer doping profiles and thicknesses (45, 50 and 80 μm). Their performance in terms of gain/collected charge and leakage current was compared before and after irradiation with neutrons and pions up to the equivalent fluences of 5 ṡ 1015 cm-2. Transient Current Technique and charge collection measurements with LHC speed electronics were employed to characterize the detectors. The thin LGAD sensors were shown to perform much better than sensors of standard thickness (∼300 μm) and offer larger charge collection with respect to detectors without gain layer for fluences gain prolongs the beneficial performance of LGADs. Pions were found to be more damaging than neutrons at the same equivalent fluence, while no significant difference was found between different producers. At very high fluences and bias voltages the gain appears due to deep acceptors in the bulk, hence also in thin standard detectors.

Analytical analysis and experimental verification of interleaved parallelogram heat sink

International Nuclear Information System (INIS)

Chen, Hong-Long; Wang, Chi-Chuan

2017-01-01

Highlights: • A novel air-cooled heat sink profile (IPFM) is proposed to compete with the typical design. • It features two different perimeters with odd fin being rectangular and the rest being parallelogram. • A new modified dimensionless parameter characterized the flow length in triangular region is proposed. • The analytical predictions are in line with the experiments for both conventional and IPFM design. • IPFM design shows a much lower pressure drop and a superior performance especially for dense fins. - Abstract: In this study, a novel air-cooled heat sink profile is proposed to compete with the conventional design. The new design is termed as IPFM (Interleaved Parallelogram Fin Module) which features two different geometrical perimeter shapes of fins. This new design not only gains the advantage of lower pressure drop for power saving; but also gains a material saving for less fin surface area. An assessment of flow impedance and performance between the conventional and IPFM heat sink is analytically investigated and experimentally verified. A new modified dimensionless friction factor for triangular region is proposed. The analytical predictions agree with experimental measurements for both conventional and IPFM design. In electronic cooling design, especially for cloud server air-cooled heat sink design, the flow pattern is usually laminar with Reynolds number being operated less than 2000. In this regime, the IPFM design shows 8–12% less of surface than conventional design when the flow rate is less than 10 CFM; yet the thermal performance is slightly inferior to the conventional design when the flowrate is raised towards 25 CFM. Yet in the test range of 5–25 CFM, a 10–15% lower flow impedance is observed. The smaller fin spacing, the more conspicuous reduction of flow impedance is observed. The optimization of cutting angle is around 35° for 10 CFM, and it is reduced to 15° at a larger flowrate of 20 CFM.

Solving the inverse heat conduction problem using NVLink capable Power architecture

Directory of Open Access Journals (Sweden)

Sándor Szénási

2017-11-01

Full Text Available The accurate knowledge of Heat Transfer Coefficients is essential for the design of precise heat transfer operations. The determination of these values requires Inverse Heat Transfer Calculations, which are usually based on heuristic optimisation techniques, like Genetic Algorithms or Particle Swarm Optimisation. The main bottleneck of these heuristics is the high computational demand of the cost function calculation, which is usually based on heat transfer simulations producing the thermal history of the workpiece at given locations. This Direct Heat Transfer Calculation is a well parallelisable process, making it feasible to implement an efficient GPU kernel for this purpose. This paper presents a novel step forward: based on the special requirements of the heuristics solving the inverse problem (executing hundreds of simulations in a parallel fashion at the end of each iteration, it is possible to gain a higher level of parallelism using multiple graphics accelerators. The results show that this implementation (running on 4 GPUs is about 120 times faster than a traditional CPU implementation using 20 cores. The latest developments of the GPU-based High Power Computations area were also analysed, like the new NVLink connection between the host and the devices, which tries to solve the long time existing data transfer handicap of GPU programming.

Comparison of feed energy costs of maintenance, lean deposition, and fat deposition in three lines of mice selected for heat loss.

Science.gov (United States)

Eggert, D L; Nielsen, M K

2006-02-01

Three replications of mouse selection populations for high heat loss (MH), low heat loss (ML), and a nonselected control (MC) were used to estimate the feed energy costs of maintenance and gain and to test whether selection had changed these costs. At 21 and 49 d of age, mice were weighed and subjected to dual x-ray densitometry measurement for prediction of body composition. At 21 d, mice were randomly assigned to an ad libitum, an 80% of ad libitum, or a 60% of ad libitum feeding group for 28-d collection of individual feed intake. Data were analyzed using 3 approaches. The first approach was an attempt to partition energy intake between costs for maintenance, fat deposition, and lean deposition for each replicate, sex, and line by multiple regression of feed intake on the sum of daily metabolic weight (kg(0.75)), fat gain, and lean gain. Approach II was a less restrictive attempt to partition energy intake between costs for maintenance and total gain for each replicate, sex, and line by multiple regression of feed intake on the sum of daily metabolic weight and total gain. Approach III used multiple regression on the entire data set with pooled regressions on fat and lean gains, and subclass regressions for maintenance. Contrasts were conducted to test the effect of selection (MH - ML) and asymmetry of selection [(MH + ML)/2 - MC] for the various energy costs. In approach I, there were no differences between lines for costs of maintenance, fat deposition, or protein deposition, but we question our ability to estimate these accurately. In approach II, selection changed both cost of maintenance (P = 0.03) and gain (P = 0.05); MH mice had greater per unit costs than ML mice for both. Asymmetry of the selection response was found in approach II for the cost of maintenance (P = 0.06). In approach III, the effect of selection (P maintenance cost, but asymmetry of selection (P > 0.17) was not evident. Sex effects were found for the cost of fat deposition (P = 0.02) in

Ricardian Productivity Differences and the Gains from Trade

OpenAIRE

Andrei A. Levchenko; Jing Zhang

2013-01-01

This paper evaluates the role of sectoral heterogeneity in determining the gains from trade. We first show analytically that in the presence of sectoral Ricardian comparative advantage, a one- sector sufficient statistic formula that uses total trade volumes as a share of total absorption systematically understates the true gains from trade. Greater relative sectoral productivity differences lead to larger disparities between the gains implied by the one-sector formula and the true gains. Usi...

Hydride heat pump with heat regenerator

Science.gov (United States)

Jones, Jack A. (Inventor)

1991-01-01

A regenerative hydride heat pump process and system is provided which can regenerate a high percentage of the sensible heat of the system. A series of at least four canisters containing a lower temperature performing hydride and a series of at least four canisters containing a higher temperature performing hydride is provided. Each canister contains a heat conductive passageway through which a heat transfer fluid is circulated so that sensible heat is regenerated. The process and system are useful for air conditioning rooms, providing room heat in the winter or for hot water heating throughout the year, and, in general, for pumping heat from a lower temperature to a higher temperature.

Active Microwave Metamaterials Incorporating Ideal Gain Devices

Directory of Open Access Journals (Sweden)

Hao Xin

2010-12-01

Full Text Available Incorporation of active devices/media such as transistors for microwave and gain media for optics may be very attractive for enabling desired low loss and broadband metamaterials. Such metamaterials can even have gain which may very well lead to new and exciting physical phenomena. We investigate microwave composite right/left-handed transmission lines (CRLH-TL incorporating ideal gain devices such as constant negative resistance. With realistic lumped element values, we have shown that the negative phase constant of this kind of transmission lines is maintained (i.e., left-handedness kept while gain can be obtained (negative attenuation constant of transmission line simultaneously. Possible implementation and challenging issues of the proposed active CRLH-TL are also discussed.

Nucleus accumbens response to gains in reputation for the self relative to gains for others predicts social media use.

Science.gov (United States)

Meshi, Dar; Morawetz, Carmen; Heekeren, Hauke R

2013-01-01

Our reputation is important to us; we've experienced natural selection to care about our reputation. Recently, the neural processing of gains in reputation (positive social feedback concerning one's character) has been shown to occur in the human ventral striatum. It is still unclear, however, how individual differences in the processing of gains in reputation may lead to individual differences in real-world behavior. For example, in the real-world, one way that people currently maintain their reputation is by using social media websites, like Facebook. Furthermore, Facebook use consists of a social comparison component, where users observe others' behavior and can compare it to their own. Therefore, we hypothesized a relationship between the way the brain processes specifically self-relevant gains in reputation and one's degree of Facebook use. We recorded functional neuroimaging data while participants received gains in reputation, observed the gains in reputation of another person, or received monetary reward. We demonstrate that across participants, when responding to gains in reputation for the self, relative to observing gains for others, reward-related activity in the left nucleus accumbens predicts Facebook use. However, nucleus accumbens activity in response to monetary reward did not predict Facebook use. Finally, a control step-wise regression analysis showed that Facebook use primarily explains our results in the nucleus accumbens. Overall, our results demonstrate how individual sensitivity of the nucleus accumbens to the receipt of self-relevant social information leads to differences in real-world behavior.

Industrial waste heat for district heating

International Nuclear Information System (INIS)

Heitner, K.L.; Brooks, P.P.

1982-01-01

Presents 2 bounding evaluations of industrial waste heat availability. Surveys waste heat from 29 major industry groups at the 2-digit level in Standard Industrial Codes (SIC). Explains that waste heat availability in each industry was related to regional product sales, in order to estimate regional waste heat availability. Evaluates 4 selected industries at the 4-digit SIC level. Finds that industrial waste heat represents a significant energy resource in several urban areas, including Chicago and Los Angeles, where it could supply all of these areas residential heating and cooling load. Points out that there is a strong need to evaluate the available waste heat for more industries at the 4-digit level. Urges further studies to identify other useful industrial waste heat sources as well as potential waste heat users

Mapping of potential heat sources for heat pumps for district heating in Denmark

International Nuclear Information System (INIS)

Lund, Rasmus; Persson, Urban

2016-01-01

The ambitious policy in Denmark on having a 100% renewable energy supply in 2050 requires radical changes to the energy systems to avoid an extensive and unsustainable use of biomass resources. Currently, wind power is being expanded and the increasing supply of electricity is slowly pushing the CHP (combined heat and power) plants out of operation, reducing the energy efficiency of the DH (district heating) supply. Here, large heat pumps for district heating is a frequently mentioned solution as a flexible demand for electricity and an energy efficient heat producer. The idea is to make heat pump use a low temperature waste or ambient heat source, but it has so far been very unclear which heat sources are actually available for this purpose. In this study eight categories of heat sources are analysed for the case of Denmark and included in a detailed spatial analysis where the identified heat sources are put in relation to the district heating areas and the corresponding demands. The analysis shows that potential heat sources are present near almost all district heating areas and that sea water most likely will have to play a substantial role as a heat source in future energy systems in Denmark. - Highlights: • The availability of heat sources for heat pumps in Denmark are mapped and quantified. • A novel methodology for assessment of low temperature industrial excess heat is presented. • There are heat sources available for 99% of district heating networks in Denmark. • The concentration of heat sources is generally bigger around bigger cities than smaller. • Ambient temperature heat sources will be more needed in district heating of big cities.

Norwegian participation in IEA Heat Pump Programme Annex 29 - final report

International Nuclear Information System (INIS)

Stene, Joern

2006-06-01

Ground source heat is a collective name for tapping, recharging and storing thermal energy at moderate temperature in the bedrock, ground water and soil (renewable energy). By means of heat pumps, ground source heating systems can be used as highly energy efficient and environmentally-friendly heating and cooling in all kinds of buildings. IEA's heat pump programme (IEA HPP) has in the period March 2004 to June 2006 carried out an Annex on heating pump systems based on ground source heat: 'Annex 29 - Ground-source heat pumps overcoming market and technical barriers'. The project has i.a. covered the development of more cost- and energy efficient solutions, identification and analysis of market obstacles, technology transfer and the task of making visible the energy economising potential and environmental gains that this type of systems represent. The six participating countries have been Canada, Japan, Norway, Sweden, USA and Austria (operating agent). Norway's participation in IEA Annex 29 has been financed by ENOVA SF, while SINTEF Energy research AS has been in charge of planning and executing the Norwegian project activities. This report provides a general presentation of ground source heat pump systems, and gives a summary of the most important Norwegian activities in IEA Annex 29, which includes: The development of a Norwegian internet home page (http://www.energy.sintef.no/prosjekt/annex29), preparation of Norwegian status report, initiation, coordination and carrying out of Norwegian research projects and reports, communication of results (technology transfer) in Norway, networking activities towards important market actors in Norway, participation and delivering discourse at international seminars (workshops), and participation at international working sessions (ml)

[Comparison of novel infrared heating plates and conventional warm water plates for piglets' creep areas in farrowing pens].

Science.gov (United States)

Strauch-Sürken, L; Wendt, M

2015-01-01

On a conventionally managed piglet-producing farm, novel infrared (IR) heating plates for piglets in the farrowing pens were tested for their suitability and compared with common warm-water (WW) heating plates. In total, 134 litters (summer n = 82, winter n = 52) were investigated, which were housed on IR or WW heating plates, respectively, with or without an extra cover plate (groups 1-4). To determine the influence of the different heat sources, the wound healing after castration and tail docking, the umbilical regression and the weight gain of the piglets were investigated. Additionally, the lying behavior of the piglets and the position of the sows' udder at the time of farrowing were examined with regard to the heating plates. Furthermore, the energy consumption and costs were compared. The piglets housed on IR heating plates displayed better wound healing after castration and tail docking than the piglets housed on WW plates. The best results were obtained in piglets kept on IR heating plates with an extra cover plate. In addition, significant benefits were demonstrated for the usage of IR heating plates regarding umbilical regression. The piglets kept on IR heating plates had a slightly better weight gain in summer, whereas there were no differences between groups during winter. The lying behavior in the creep areas was similar in all groups. In general, with increasing age the percentage of time piglets spent in the lying position on the plates decreased. The percentage of time lying on the plates was higher in winter than in summer. At farrowing, 74.6% of all investigated sows directed their udder towards the heating plates. With the IR heating plates, this behavior occurred significantly more often. The energy consumption (kWh) per litter was significantly lower for the IR heating plates (electric power) both in winter and summer in comparison with the WW plates (gas). The energy costs were comparable in summer, but were higher for the IR heating plates

Parametric investigation of a non-constant cross sectional area air to air heat exchanger

International Nuclear Information System (INIS)

Cárdenas, Bruno; Garvey, Seamus; Kantharaj, Bharath; Simpson, Michael

2017-01-01

Highlights: • Evaluation of complex geometry aimed at minimizing volume per unit of exergy transfer. • The use of a non-constant cross-section for the heat exchanger is proposed. • The performance gains attainable via modern manufacturing techniques are discussed. • The trade-off between overall exergy efficiency and cost is thoroughly analysed. • A quadratic proportion between volume and characteristic dimension has been found. - Abstract: The present article addresses the design, mathematical modelling and analysis of a novel highly exergy-efficient air to air heat exchanger. An intricate design based on an hexagonal mesh is proposed for the cross-sectional area of the heat exchanger with aims to explore the performance gains that can be obtained by exploiting the capabilities and benefits offered by modern fabrication techniques such as additive manufacturing. Special attention is paid to understanding the relationship or trade-off that exists between the overall exergy efficiency of the heat exchanger and its cost. The iterative algorithm used to find the geometrical parameters that yield the best performance in terms of volume of material required per unit of exergy transfer at a certain level of efficiency, as well as the assumptions and simplifications made, are comprehensively explained. It has been found through the analyses carried out performed, which are thoroughly discussed throughout the paper, that if the characteristic dimension of the heat exchanger is scaled up by a factor of n, the volume of material per kW of exergy transfer at certain exergy efficiency will increase by a factor of n squared. This is a very important observation, possibly applicable to other types of heat exchangers, that indicates that performance improves dramatically at smaller scales. The overall performance of the case study presented is satisfactory, a volume of material as low as 84.8 cm"3 for one kW of exergy transfer can be achieved with a 99% exergy

Simulation of temperature in office with building integrated heating and cooling system

DEFF Research Database (Denmark)

Weitzmann, Peter

2002-01-01

In this paper a numerical investigation of the thermal indoor environment has been performed for an office with building integrated hydronic heating and cooling system. Today office buildings are designed in such a way, and have such high internal heat loads and solar gains, that some kind...... of cooling is normally necessary for most of the year. Even in as cool climates as in the Nordic countries. The way the cooling is often achieved is through air conditioning. This can in many cases lead to sick building syndrome (SBS) symptoms, and furthermore it results in high energy consumption periods...... the temperature of the concrete to a level slightly below the desired room temperature, the concrete will work as an absorber for the excess heat in the office. This can significantly reduce the need for air conditioning, which will give both improved indoor climate and lower energy costs in the building...

Brillouin gain enhancement in nano-scale photonic waveguide

Science.gov (United States)

Nouri Jouybari, Soodabeh

2018-05-01

The enhancement of stimulated Brillouin scattering in nano-scale waveguides has a great contribution in the improvement of the photonic devices technology. The key factors in Brillouin gain are the electrostriction force and radiation pressure generated by optical waves in the waveguide. In this article, we have proposed a new scheme of nano-scale waveguide in which the Brillouin gain is considerably improved compared to the previously-reported schemes. The role of radiation pressure in the Brillouin gain was much higher than the role of the electrostriction force. The Brillouin gain strongly depends on the structural parameters of the waveguide and the maximum value of 12127 W-1 m-1 is obtained for the Brillouin gain.

Method and system for edge cladding of laser gain media

Science.gov (United States)

Bayramian, Andrew James; Caird, John Allyn; Schaffers, Kathleen Irene

2014-03-25

A gain medium operable to amplify light at a gain wavelength and having reduced transverse ASE includes an input surface and an output surface opposing the input surface. The gain medium also includes a central region including gain material and extending between the input surface and the output surface along a longitudinal optical axis of the gain medium. The gain medium further includes an edge cladding region surrounding the central region and extending between the input surface and the output surface along the longitudinal optical axis of the gain medium. The edge cladding region includes the gain material and a dopant operable to absorb light at the gain wavelength.

Experimental studies and economic considerations on a living space heated through passive solar gain and through electric power

Directory of Open Access Journals (Sweden)

Luminosu Iona

2003-01-01

Full Text Available The Trombe wall, of an area AT = 8.8 m, built on the southern facade of a room, heats the accommodation during the transition months, complementary to electric power. The statistical processing of the experimental data led to a global quantitative image of the wall’s behavior during the average day of the months March, April, September, and October 1999. The inner climate parameters are: tint = = 21 °C, trad = 17.9 °C, troom= 19.5 °C, j= 35-70%, E Î80 + 120 lx. The thermal comfort factor is B = -0.325. These values insure a room’s comfort close to the optimal one prescribed by the hygienists. The heliothermal conversion’s efficiency is hT = 10.4%. The proportion of heat supplied by the wall in the entire energy required by the room is hheat = 45.8%. The wall’s specific cost is Pu = 24.9 € /m. The write-off period of the initial investment is n = 53 years. The development of passive solar architecture in the Euro-region Danube-Cris-Mures-Tisa which includes the town of Timisoara (45° north, 22° east, was proven feasible by the experiments from both the energy and the economical point of view.

Net energy gain from DT fusion

International Nuclear Information System (INIS)

Buende, R.

1985-01-01

The net energy which can be gained from an energy raw material by means of a certain conversion system is deduced as the figure-of-merit which adequately characterizes the net energy balance of utilizing an energy source. This potential net energy gain is determined for DT fusion power plants. It is represented as a function of the degree of exploitation of the energy raw material lithium ore and is compared with the net energy which can be gained with LW and FBR power plants by exploiting uranium ore. The comparison clearly demonstrates the net energetic advantage of DT fusion. A sensitivity study shows that this holds even if the energy expenditure for constructing and operating is drastically increased

Nucleus accumbens response to gains in reputation for the self relative to gains for others predicts social media use

Directory of Open Access Journals (Sweden)

Dar eMeshi

2013-08-01

Full Text Available Our reputation is important to us; we’ve experienced natural selection to care about our reputation. Recently, the neural processing of gains in reputation (positive social feedback concerning one’s character has been shown to occur in the human ventral striatum. It is still unclear, however, how individual differences in the processing of gains in reputation may lead to individual differences in real-world behavior. For example, in the real-world, one way that people currently maintain their reputation is by using social media websites, like Facebook. Furthermore, Facebook use consists of a social comparison component, where users observe others’ behavior and can compare it to their own. Therefore, we hypothesized a relationship between the way the brain processes specifically self-relevant gains in reputation and one’s degree of Facebook use. We recorded functional neuroimaging data while participants received gains in reputation, observed the gains in reputation of another person, or received monetary reward. We demonstrate that across participants, when responding to gains in reputation for the self, relative to observing gains for others, reward-related activity in the left nucleus accumbens predicts Facebook use. However, nucleus accumbens activity in response to monetary reward did not predict Facebook use. Finally, a control step-wise regression analysis showed that Facebook use primarily explains our results in the nucleus accumbens. Overall, our results demonstrate how individual sensitivity of the nucleus accumbens to the receipt of self-relevant social information leads to differences in real-world behavior.

Field investigation on consumer behavior and hydraulic performance of a district heating system in Tianjin, China

Energy Technology Data Exchange (ETDEWEB)

Xu, Baoping; Fu, Lin; Di, Hongfa [Department of Building Science, Tsinghua University, Beijing 100084 (China)

2009-02-15

With the implementation of heat reforms in China, the application of thermostatic radiator valves (TRVs) has been gaining popularity in the new-style district heating systems (DHSs). The objective of this study was to investigate consumer behavior (including regulation of TRVs and opening of windows) and its influences on the hydraulic performance and energy consumption of individuals and the whole system. The concurrence rate of individual behaviors and hydraulic interactions between individuals were analyzed. This study should be helpful to gain a comprehensive understanding of the new DHSs in China and consider a proper design/control strategy for these systems. Questionnaires and field observations of consumer behavior, tests of hydraulic performance, and surveys of energy consumption were carried out in a DHS in Tianjin, which was one of the heat metering and billing demonstration projects in China. The main results of the tests were as follows: water flow performance in apartment-level heating systems were diverse because consumers' behavior was varied and unpredictable, and the hydraulic interaction between consumers living along the line of a vertical pipe was obvious, and was stronger for terminal consumers with their TRVs set to higher values; however, flow variations in the whole DHS, which included 910 households, were relatively constant. A probability analysis was carried out to explain this phenomenon, and the conclusion was drawn that when there were more than 200 consumers, the stochastic consumer regulation behavior would bring less than 10% of total flow variations. Finally, the power consumption of the circulation pump, heat consumption and energy-saving potential of this type of DHS were discussed and some suggestions for TRV regulation and pump operation were made. (author)

Maximum-power-point tracking control of solar heating system

KAUST Repository

Huang, Bin-Juine

2012-11-01

The present study developed a maximum-power point tracking control (MPPT) technology for solar heating system to minimize the pumping power consumption at an optimal heat collection. The net solar energy gain Q net (=Q s-W p/η e) was experimentally found to be the cost function for MPPT with maximum point. The feedback tracking control system was developed to track the optimal Q net (denoted Q max). A tracking filter which was derived from the thermal analytical model of the solar heating system was used to determine the instantaneous tracking target Q max(t). The system transfer-function model of solar heating system was also derived experimentally using a step response test and used in the design of tracking feedback control system. The PI controller was designed for a tracking target Q max(t) with a quadratic time function. The MPPT control system was implemented using a microprocessor-based controller and the test results show good tracking performance with small tracking errors. It is seen that the average mass flow rate for the specific test periods in five different days is between 18.1 and 22.9kg/min with average pumping power between 77 and 140W, which is greatly reduced as compared to the standard flow rate at 31kg/min and pumping power 450W which is based on the flow rate 0.02kg/sm 2 defined in the ANSI/ASHRAE 93-1986 Standard and the total collector area 25.9m 2. The average net solar heat collected Q net is between 8.62 and 14.1kW depending on weather condition. The MPPT control of solar heating system has been verified to be able to minimize the pumping energy consumption with optimal solar heat collection. © 2012 Elsevier Ltd.

Optimised air-heating for Minergie-P and passive housing; Optimierte Luftheizung fuer Minergie-P und Passivhaeuser

Energy Technology Data Exchange (ETDEWEB)

Haas, A.; Dorer, V.

2004-07-01

This extensive report for the Swiss Federal Office of Energy (SFOE) presents the results of a project concerning so-called 'passive' houses which exhibit extremely low energy consumption. The authors state that the findings also apply to the Swiss 'Minergie-P' standard. The aims of the project are quoted, including ways of simplifying the air distribution system, possibilities of using air-based heating systems for non-passive housing, how the building's mass can be used as a heat exchanger and for heat storage and what requirements are to be placed on the small wood-fired ovens often found in such houses. Topics discussed include temperatures and temperature gradients, thermal comfort, draught risks and air-flow rates. Further, questions concerning heat-distribution and control systems, fire and noise protection and humidity are discussed, as are heat losses and gains. Examples of dwellings being examined as part of pilot and demonstration projects are given.

Isothermal calorimeter for measurements of time-dependent heat generation rate in individual supercapacitor electrodes

Science.gov (United States)

Munteshari, Obaidallah; Lau, Jonathan; Krishnan, Atindra; Dunn, Bruce; Pilon, Laurent

2018-01-01

Heat generation in electric double layer capacitors (EDLCs) may lead to temperature rise and reduce their lifetime and performance. This study aims to measure the time-dependent heat generation rate in individual carbon electrode of EDLCs under various charging conditions. First, the design, fabrication, and validation of an isothermal calorimeter are presented. The calorimeter consisted of two thermoelectric heat flux sensors connected to a data acquisition system, two identical and cold plates fed with a circulating coolant, and an electrochemical test section connected to a potentiostat/galvanostat system. The EDLC cells consisted of two identical activated carbon electrodes and a separator immersed in an electrolyte. Measurements were performed on three cells with different electrolytes under galvanostatic cycling for different current density and polarity. The measured time-averaged irreversible heat generation rate was in excellent agreement with predictions for Joule heating. The reversible heat generation rate in the positive electrode was exothermic during charging and endothermic during discharging. By contrast, the negative electrode featured both exothermic and endothermic heat generation during both charging and discharging. The results of this study can be used to validate existing thermal models, to develop thermal management strategies, and to gain insight into physicochemical phenomena taking place during operation.

Photomultiplier gain stabilisation

International Nuclear Information System (INIS)

Le Baud, P.; Sautiez, B.

1958-07-01

By the control and adjustment of magnetic deflection applied to the electron beam of a photomultiplier it has proved possible to flatten the gain curve, forming plateaux at levels dependent upon the voltage at intake. It should be possible to add this simple device to most photomultipliers on the market today. (author) [fr

When, How and Why is Loss-Framing More Effective than Gain- and Non-Gain-Framing in the Promotion of Detection Behaviors?

OpenAIRE

Bosone, Lucia; Martinez, Frédéric

2017-01-01

This short paper aims to untangle the effect of loss-framing versus gain and non-gain; explaining when, how and why it influences individuals’ intentions to engage in cholesterol screening. We argue that framing-effects are (1) significant only when individuals perceive the issue to be highly relevant and (2) are mediated by perceived negative consequences (resulting from undergoing the test) and response-efficacy. In a 2(issue-relevance: high vs low) × 3(framing: gain vs non-gain vs loss) ex...

Thermoregulation and thermal perception in the cold and heat before and after intermittent heat adaptation

Science.gov (United States)

Issing, K.; Fuhr, E.

1986-09-01

Students wearing swim suits were exposed for 30 min to neutral room temperature (TR=28‡C). During the following 60 min they were subjected to gradual decreases or increases of room temperature reaching 12‡C or 45‡C, respectively. Static thermal stimuli were applied to the palms of the right (38‡C) and left (25‡C) hands. Hands and feet of all subjects were thermally isolated at 22‡C ambient temperature. General thermal comfort (GTC), local thermal comfort (LTC), skin blood flow (which is proportional to heat transport index λ) several body temperatures, oxygen-consumption(dot V_{O_2 } ), and sweat rate (S), were measured. After moderate intermittent heat exposures (7 times for 1h at TR=42.5‡C) the experiments started again. From GTC, LTC, or λ as functions of TR, no new knowledge about thermoregulatory or adaptive mechanisms was available. The high λ in the cold stimulated left hand, however, and the oscillatory thresholds (λOSC) for rhythmic vasomotion indicated the peripheral influence of skin temperature, as well as local, mean skin temperature (¯Ts) and core temperature. When exposed to moderate temperature decreases or increases the body seems to react only with increasing thermal resistance by vasoconstriction or an increase of sweat rate, respectively. Moderate heat adaptation is only able to raise sweat rate, but not the thresholds and gain of the S-function. We assume that functional studies of adaptive modifications in humans must be conducted at temperatures greatly beyond those used in these experiments.

Agent-based modeling and simulation of clean heating system adoption in Norway

Energy Technology Data Exchange (ETDEWEB)

Sopha, Bertha Maya

2011-03-15

A sound climate policy encouraging clean energy investment is important to mitigate global warming. Previous research has demonstrated that consumer choice indeed plays an important role in adoption of sustainable technologies. This thesis strives to gain a better understanding of consumers' decision-making on heating systems and to explore the potential application of agent-based modeling (ABM) in exploring mechanism underlying adoption in which heating system adoption by Norwegian households is taken up as a case study. An interdisciplinary approach, applying various established theories including those of psychology, is applied to create a model for consumer behavior and implement this behavior in an Agent-Based Model (ABM) to simulate heating technology diffusion. A mail-survey, carried out in autumn 2008, is a means to collect information for parameterizing the agent-based model, for gaining empirical facts, and for validating the developed model at micro-level. Survey sample consisted of 1500 Norwegian households drawn from population register and 1500 wood pellet users in Norway. The response rates were 10.3% and 34.6% for population sample and wood pellet sample respectively. This study is divided into two parts; empirical analysis and agent-based simulation. The empirical analysis aims at fully understanding the important aspects of adoption decision and their implications, in order to assist simulation. The analysis particularly contributes to the identification of differences/similarities between adopters and non adopters of wood pellet heating with respects to some key points of adoption derived from different theories, psychological factors underlying the adoption-decision of wood pellet heating, and the rationales underlying Norwegian households' decisions regarding their future heating system. The simulation study aims at exploring the mechanism of heterogeneous household decision-making giving rise to the diffusion of heating systems, and

Heating networks and domestic central heating systems

Energy Technology Data Exchange (ETDEWEB)

Kamler, W; Wasilewski, W

1976-08-01

This is a comprehensive survey of the 26 contributions from 8 European countries submitted to the 3rd International District Heating Conference in Warsaw held on the subject 'Heating Networks and Domestic Central Heating Systems'. The contributions are grouped according to 8 groups of subjects: (1) heat carriers and their parameters; (2) system of heating networks; (3) calculation and optimization of heating networks; (4) construction of heating networks; (5) operation control and automation; (6) operational problems; (7) corrosion problems; and (8) methods of heat accounting.

Heat transfer and critical heat flux in a asymmetrically heated tube helicoidal flow

International Nuclear Information System (INIS)

Boscary, J.

1995-10-01

The design of plasma facing components is crucial for plasma performance in next fusion reactors. These elements will be submitted to very high heat flux. They will be actively water-cooled by swirl tubes in the subcooled boiling regime. High heat flux experiments were conducted in order to analyse the heat transfer and to evaluate the critical heat flux. Water-cooled mock-ups were one-side heated by an electron beam gun for different thermal-hydraulic conditions. The critical heat flux was detected by an original method based on the isotherm modification on the heated surface. The wall heat transfer law including forced convection and subcooled boiling regimes was established. Numerical calculations of the material heat transfer conduction allowed the non-homogeneous distribution of the wall temperature and of the wall heat flux to be evaluated. The critical heat flux value was defined as the wall maximum heat flux. A critical heat flux model based on the liquid sublayer dryout under a vapor blanket was established. A good agreement with test results was found. (author). 198 refs., 126 figs., 21 tabs

Determinants of Weight Gain During Adjuvant Endocrine Therapy and Association of Such Weight Gain With Recurrence in Long-term Breast Cancer Survivors.

Science.gov (United States)

Raghavendra, Akshara; Sinha, Arup K; Valle-Goffin, Janeiro; Shen, Yu; Tripathy, Debu; Barcenas, Carlos H

2018-02-01

Weight gain is a negative prognostic factor in breast cancer (BC) patients. The risk factors for weight gain during adjuvant endocrine therapy (ET) and the extent to which such weight gain is associated with disease recurrence remain unclear. We retrospectively identified a cohort of women with a diagnosis of stage I-III, hormone receptor-positive, human epidermal growth factor receptor 2-negative BC from January 1997 to August 2008, who had received initial treatment at the MD Anderson Cancer Center, had completed 5 years of ET, and had remained free of locoregional or distant relapse or contralateral BC for ≥ 5 years after diagnosis. The weight change at the end of 5 years of ET was measured as the percentage of the change in weight from the start of ET, with a weight gain of > 5% considered clinically significant. Multivariable logistic regression and Cox proportional hazards models were used to assess the determinants of such weight gain and the risk of recurrence after 5 years. Of 1282 long-term BC survivors, 432 (33.7%) had a weight gain of > 5% after 5 years of ET. Women who were premenopausal at diagnosis were 1.40 times more likely than women who were postmenopausal at diagnosis to have a weight gain of > 5%. Asian women had the lowest risk of gaining weight. The recurrence risks of patients who had gained weight and those who had not were not significantly different. Premenopausal BC patients had an increased risk of weight gain after 5 years of ET; however, BC patients with a weight gain of > 5% did not have an increased risk of disease recurrence. Copyright © 2017 Elsevier Inc. All rights reserved.

Transient optical gain in germanium quantum wells

Energy Technology Data Exchange (ETDEWEB)

Chatterjee, Sangam; Lange, Christoph; Koester, Niko S.; Schaefer, Martin; Kira, Mackillo; Koch, Stephan W. [Faculty of Physics and Materials Sciences Center, Philipps-Universitaet Marburg (Germany); Chrastina, Daniel; Isella, Giovanni; Kaenel, Hans von [CNISM, Como (Italy); L-NESS, Dipartimento di Fisica del Politecnico di Milano, Como (Italy); Sigg, Hans [Laboratory for Micro and Nanotecnology, Paul Scherrer Institut, Villigen PSI (Switzerland)

2010-07-01

One of today's most-sought goals in semiconductor technology is the monolithic integration of microelectronics and photonics on Si. Optical gain is, in general, not expected for Si and Ge or its alloys due to the indirect nature of the band gap in this material system. Here, we show that Ge/SiGe QWs show transient optical gain and may thus be used as an optically-pumped amplifier at room temperature. Further, the nonequilibrium effects which govern the relaxation dynamics of the optically injected carrier distributions in this material were observed and analyzed using a microscopic many-body theory. Strong non-equilibrium gain was obtained on a sub-100 fs time scale. Long-lived gain arising from {gamma}-point transitions is overcompensated by a process bearing the character of free carrier absorption.

Optical properties of nanowire metamaterials with gain

DEFF Research Database (Denmark)

Isidio de Lima, Joaquim Junior; Adam, Jost; Rego, Davi

2016-01-01

The transmittance, reflectance and absorption of a nanowire metamaterial with optical gain are numerically simulated and investigated. It is assumed that the metamaterial is represented by aligned silver nanowires embedded into a semiconductor matrix, made of either silicon or gallium phosphide....... The gain in the matrix is modeled by adding a negative imaginary part to the dielectric function of the semiconductor. It is found that the optical coefficients of the metamaterial depend on the gain magnitude in a non-trivial way: they can both increase and decrease with gain depending on the lattice...... constant of the metamaterial. This peculiar behavior is explained by the field redistribution between the lossy metal nanowires and the amplifying matrix material. These findings are significant for a proper design of nanowire metamaterials with low optical losses for diverse applications....

A review of large-scale solar heating systems in Europe

International Nuclear Information System (INIS)

Fisch, M.N.; Guigas, M.; Dalenback, J.O.

1998-01-01

Large-scale solar applications benefit from the effect of scale. Compared to small solar domestic hot water (DHW) systems for single-family houses, the solar heat cost can be cut at least in third. The most interesting projects for replacing fossil fuels and the reduction of CO 2 -emissions are solar systems with seasonal storage in combination with gas or biomass boilers. In the framework of the EU-APAS project Large-scale Solar Heating Systems, thirteen existing plants in six European countries have been evaluated. lie yearly solar gains of the systems are between 300 and 550 kWh per m 2 collector area. The investment cost of solar plants with short-term storage varies from 300 up to 600 ECU per m 2 . Systems with seasonal storage show investment costs twice as high. Results of studies concerning the market potential for solar heating plants, taking new collector concepts and industrial production into account, are presented. Site specific studies and predesign of large-scale solar heating plants in six European countries for housing developments show a 50% cost reduction compared to existing projects. The cost-benefit-ratio for the planned systems with long-term storage is between 0.7 and 1.5 ECU per kWh per year. (author)

Field Performance of Inverter-Driven Heat Pumps in Cold Climates

Energy Technology Data Exchange (ETDEWEB)

Williamson, James [Consortium of Advanced Residential Buildings, Norwalk, CT (United States); Aldrich, Robb [Consortium of Advanced Residential Buildings, Norwalk, CT (United States)

2015-08-19

Traditionally, air-source heat pumps (ASHPs) have been used more often in warmer climates; however, some new ASHPs are gaining ground in colder areas. These systems operate at subzero (Fahrenheit) temperatures and many do not include backup electric resistance elements. There are still uncertainties, however, about capacity and efficiency in cold weather. Also, questions such as “how cold is too cold?” do not have clear answers. These uncertainties could lead to skepticism among homeowners; poor energy savings estimates; suboptimal system selection by heating, ventilating, and air-conditioning contractors; and inconsistent energy modeling. In an effort to better understand and characterize the heating performance of these units in cold climates, the U.S. Department of Energy Building America team, Consortium for Advanced Residential Buildings (CARB), monitored seven inverter-driven, ductless ASHPs across the Northeast. Operating data were collected for three Mitsubishi FE18 units, three Mitsubishi FE12 units, and one Fujitsu 15RLS2 unit. The intent of this research was to assess heat output, electricity consumption, and coefficients of performance (COPs) at various temperatures and load conditions. This assessment was accomplished with long- and short-term tests that measured power consumption; supply, return, and outdoor air temperatures; and airflow through the indoor fan coil.

Recurrent selection as breeding strategy for heat tolerance in wheat

OpenAIRE

Juarez Campolina Machado; Moacil Alves de Souza; Davi Melo de Oliveira; Adeliano Cargnin; Aderico Júnior Badaró Pimentel; Josiane Cristina de Assis

2010-01-01

The development of heat-tolerant varieties is an important goal of wheat breeding programs, requiringefficient selection methods. In the present study the use of recurrent selection was evaluated as a strategy to improve heatstress tolerance in wheat. Two cycles of recurrent selection were performed in experiments conducted in research areas of theUniversidade Federal de Viçosa, located in Coimbra-MG and Viçosa-MG, in 2004 and 2007, in two growing seasons (summerand winter). The genetic gain ...

Industrial excess heat for district heating in Denmark

International Nuclear Information System (INIS)

Bühler, Fabian; Petrović, Stefan; Karlsson, Kenneth; Elmegaard, Brian

2017-01-01

Highlights: •Method for utilisation potential of industrial excess heat for district heating. •Industrial excess heat from thermal processes is quantified at single production units. •Linking of industrial excess heat sources and district heating demands done in GIS. •Excess heat recovery using direct heat transfer and heat pumps. •5.1% of the Danish district heating demand could be supplied by industrial excess heat. -- Abstract: Excess heat is available from various sources and its utilisation could reduce the primary energy use. The accessibility of this heat is however dependent amongst others on the source and sink temperature, amount and potential users in its vicinity. In this work a new method is developed which analyses excess heat sources from the industrial sector and how they could be used for district heating. This method first allocates excess heat to single production units by introducing and validating a new approach. Spatial analysis of the heat sources and consumers are then performed to evaluate the potential for using them for district heating. In this way the theoretical potential of using the excess heat for covering the heating demand of buildings is determined. Through the use of industry specific temperature profiles the heat usable directly or via heat pumps is further found. A sensitivity analysis investigates the impact of future energy efficiency measures in the industry, buildings and the district heating grid on the national potential. The results show that for the case study of Denmark, 1.36 TWh of district heat could be provided annually with industrial excess heat from thermal processes which equals 5.1% of the current demand. More than half of this heat was found to be usable directly, without the need for a heat pump.

Weight gain in women diagnosed with breast cancer.

Science.gov (United States)

Demark-Wahnefried, W; Rimer, B K; Winer, E P

1997-05-01

This review of the literature indicates that weight gain is a common observation among women after the diagnosis of breast cancer. Gains in weight range from 0 to 50 lb and are influenced by menopausal status; nodal status; and the type, duration, and intensity of treatment. Weight gain appears to be greater among premenopausal women; among those who are node positive; and among those receiving higher dose, longer duration, and multiagent regimens. Psychosocial research suggests that weight gain has a profoundly negative impact on quality of life in patients with breast cancer. Recent findings also suggest that weight gain during therapy may increase the risk of recurrence and decrease survival. Although weight gain in patients with breast cancer is clinically well appreciated, little research has been conducted to investigate the underlying mechanisms of energy imbalance. Changes in rates of metabolism, physical activity, and dietary intake are all plausible mechanisms and call for more research. Further study will provide valuable insight into the problem of weight gain and encourage effective interventions to improve the quality and quantity of life for the woman with breast cancer. Until more is known, however, dietetics practitioners will have to monitor and work individually with patients with breast cancer and use empirical approaches to achieve the important goal of weight management.

Gain Shift Corrections at Chi-Nu

Energy Technology Data Exchange (ETDEWEB)

Brown, Tristan Brooks [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Univ. of Massachusetts, Lowell, MA (United States). Dept. of Physics and Applied Physics; Devlin, Matthew James [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2016-08-30

Ambient conditions have the potential to cause changes in liquid scintillator detector gain that vary with time and temperature. These gain shifts can lead to poor resolution in both energy as well as pulse shape discrimination. In order to correct for these shifts in the Chi-Nu high energy array, a laser system has been developed for calibration of the pulse height signals.

Maximum gain of Yagi-Uda arrays

DEFF Research Database (Denmark)

Bojsen, J.H.; Schjær-Jacobsen, Hans; Nilsson, E.

1971-01-01

Numerical optimisation techniques have been used to find the maximum gain of some specific parasitic arrays. The gain of an array of infinitely thin, equispaced dipoles loaded with arbitrary reactances has been optimised. The results show that standard travelling-wave design methods are not optimum....... Yagi–Uda arrays with equal and unequal spacing have also been optimised with experimental verification....

Surface roughness effects on heat transfer in Couette flow

International Nuclear Information System (INIS)

Elia, G.G.

1981-01-01

A cell theory for viscous flow with rough surfaces is applied to two basic illustrative heat transfer problems which occur in Couette flow. Couette flow between one adiabatic surface and one isothermal surface exhibits roughness effects on the adiabatic wall temperature. Two types of rough cell adiabatic surfaces are studied: (1) perfectly insulating (the temperature gradient vanishes at the boundary of each cell); (2) average insulating (each cell may gain or lose heat but the total heat flow at the wall is zero). The results for the roughness on a surface in motion are postulated to occur because of fluid entrainment in the asperities on the moving surface. The symmetry of the roughness effects on thermal-viscous dissipation is discussed in detail. Explicit effects of the roughness on each surface, including combinations of roughness values, are presented to enable the case where the two surfaces may be from different materials to be studied. The fluid bulk temperature rise is also calculated for Couette flow with two ideal adiabatic surfaces. The effect of roughness on thermal-viscous dissipation concurs with the viscous hydrodynamic effect. The results are illustrated by an application to lubrication. (Auth.)

Comparative evaluation of three heat transfer enhancement strategies in a grooved channel

Energy Technology Data Exchange (ETDEWEB)

Herman, C.; Kang, E. [Dept. of Mechanical Engineering, Johns Hopkins Univ., Baltimore, MD (United States)

2001-09-01

Results of a comparative evaluation of three heat transfer enhancement strategies for forced convection cooling of a parallel plate channel populated with heated blocks, representing electronic components mounted on printed circuit boards, are reported. Heat transfer in the reference geometry, the asymmetrically heated parallel plate channel, is compared with that for the basic grooved channel, and the same geometry enhanced by cylinders and vanes placed above the downstream edge of each heated block. In addition to conventional heat transfer and pressure drop measurements, holographic interferometry combined with high-speed cinematography was used to visualize the unsteady temperature fields in the self-sustained oscillatory flow. The locations of increased heat transfer within one channel periodicity depend on the enhancement technique applied, and were identified by analyzing the unsteady temperature distributions visualized by holographic interferometry. This approach allowed gaining insight into the mechanisms responsible for heat transfer enhancement. Experiments were conducted at moderate flow velocities in the laminar, transitional and turbulent flow regimes. Reynolds numbers were varied in the range Re = 200-6500, corresponding to flow velocities from 0.076 to 2.36 m/s. Flow oscillations were first observed between Re = 1050 and 1320 for the basic grooved channel, and around Re = 350 and 450 for the grooved channels equipped with cylinders and vanes, respectively. At Reynolds numbers above the onset of oscillations and in the transitional flow regime, heat transfer rates in the investigated grooved channels exceeded the performance of the reference geometry, the asymmetrically heated parallel plate channel. Heat transfer in the grooved channels enhanced with cylinders and vanes showed an increase by a factor of 1.2-1.8 and 1.5-3.5, respectively, when compared to data obtained for the basic grooved channel; however, the accompanying pressure drop penalties

EXPERIENCE OF UTILIZATION OF CAPACITY BANKS AND SCHEMES OF FREQUENCY REGULATION IN MUNICIPAL CENTRALIZED HEATING SYSTEM OF CHISINAU

Directory of Open Access Journals (Sweden)

CHERNEI M

2013-04-01

Full Text Available The current paper provides a brief summary of the district heating system of the municipality Chisinau, including heat power sources, heat distribution network, production and consumption development over the past two decades and other data. Also, the priority investment projects realized by JSC "Termocom" are being presented. The company had implemented an automated monitoring system for the heat power production, transportation and distribution. For many years, the company used bellows pipes with polyurethane insulation, ball valves and plate heat exchangers. 14 out of 21 district heating boiler stations were upgraded 10 were completely automated having as a result no further need in full-time duty personnel there. The experience gained in the implementation of capacity banks and frequency inverters, summarizing the benefits and achieved results, is also presented in the current paper. It is to be underlined that in 2011 the company achieved decrease in electricity consumption by about 30% in comparison with 2005.

Point Information Gain and Multidimensional Data Analysis

Directory of Open Access Journals (Sweden)

Renata Rychtáriková

2016-10-01

Full Text Available We generalize the point information gain (PIG and derived quantities, i.e., point information gain entropy (PIE and point information gain entropy density (PIED, for the case of the Rényi entropy and simulate the behavior of PIG for typical distributions. We also use these methods for the analysis of multidimensional datasets. We demonstrate the main properties of PIE/PIED spectra for the real data with the examples of several images and discuss further possible utilizations in other fields of data processing.

Analyzing Design Heating Loads in Superinsulated Buildings

Energy Technology Data Exchange (ETDEWEB)

Arena, Lois [Consortium for Advanced Residential Buildings, Norwalk, CT (United States)

2015-06-01

Super-insulated homes offer many benefits including improved comfort, reduced exterior noise penetration, lower energy bills, and the ability to withstand power and fuel outages under much more comfortable conditions than a typical home. While these homes aren't necessarily constructed with excessive mass in the form of concrete floors and walls, the amount of insulation and the increase in the thickness of the building envelope can lead to a mass effect, resulting in the structures ability to store much more heat than a code built home. This results in a very low thermal inertia making the building much less sensitive to drastic temperature swings thereby decreasing the peak heating load demand. During the winter of 2013/2014, CARB monitored the energy use of three homes in climate zone 6 in an attempt to evaluate the accuracy of two different mechanical system sizing methods for low load homes. Based on the results, it is recommended that internal and solar gains be included and some credit for thermal inertia be used in sizing calculations for super insulated homes.

Adequacy of Prenatal Care and Gestational Weight Gain.

Science.gov (United States)

Yeo, SeonAe; Crandell, Jamie L; Jones-Vessey, Kathleen

2016-02-01

The goal of prenatal care is to maximize health outcomes for a woman and her fetus. We examined how prenatal care is associated with meeting the 2009 Institute of Medicine (IOM) guidelines for gestational weight gain. The study used deidentified birth certificate data supplied by the North Carolina State Center for Health Statistics. The sample included 197,354 women (≥18 years) who delivered singleton full-term infants in 2011 and 2012. A generalized multinomial model was used to identify how adequate prenatal care was associated with the odds of gaining excessive or insufficient weight during pregnancy according to the 2009 IOM guidelines. The model adjusted for prepregnancy body size, sociodemographic factors, and birth weight. A total of 197,354 women (≥18 years) delivered singleton full-term infants. The odds ratio (OR) for excessive weight gain was 2.44 (95% CI 2.37-2.50) in overweight and 2.33 (95% CI 2.27-2.40) in obese women compared with normal weight women. The OR for insufficient weight gain was 1.15 (95% CI 1.09-1.22) for underweight and 1.34 (95% CI 1.30-1.39) for obese women compared with normal weight women. Prenatal care at the inadequate or intermediate levels was associated with insufficient weight gain (OR: 1.32, 95% CI 1.27-1.38; OR: 1.15, 95% CI 1.09-1.21, respectively) compared with adequate prenatal care. Women with inadequate care were less likely to gain excessive weight (OR: 0.88, 95% CI 0.86-0.91). Whereas prenatal care was effective for preventing insufficient weight gain regardless of prepregnancy body size, educational background, and racial/ethnic group, there were no indications that adequate prenatal care was associated with reduced risk for excessive gestational weight gain. Further research is needed to improve prenatal care programs for preventing excess weight gain.

Potential gains from hospital mergers in Denmark.

Science.gov (United States)

Kristensen, Troels; Bogetoft, Peter; Pedersen, Kjeld Moeller

2010-12-01

The Danish hospital sector faces a major rebuilding program to centralize activity in fewer and larger hospitals. We aim to conduct an efficiency analysis of hospitals and to estimate the potential cost savings from the planned hospital mergers. We use Data Envelopment Analysis (DEA) to estimate a cost frontier. Based on this analysis, we calculate an efficiency score for each hospital and estimate the potential gains from the proposed mergers by comparing individual efficiencies with the efficiency of the combined hospitals. Furthermore, we apply a decomposition algorithm to split merger gains into technical efficiency, size (scale) and harmony (mix) gains. The motivation for this decomposition is that some of the apparent merger gains may actually be available with less than a full-scale merger, e.g., by sharing best practices and reallocating certain resources and tasks. Our results suggest that many hospitals are technically inefficient, and the expected "best practice" hospitals are quite efficient. Also, some mergers do not seem to lower costs. This finding indicates that some merged hospitals become too large and therefore experience diseconomies of scale. Other mergers lead to considerable cost reductions; we find potential gains resulting from learning better practices and the exploitation of economies of scope. To ensure robustness, we conduct a sensitivity analysis using two alternative returns-to-scale assumptions and two alternative estimation approaches. We consistently find potential gains from improving the technical efficiency and the exploitation of economies of scope from mergers.

Comparison of boiling heat transfer coefficient and pressure drop correlations for evaporators

International Nuclear Information System (INIS)

Eskin, N.; Arslan, G.

2009-01-01

Evaporator design is an important aspect for the HVAC industry. As the demand for more efficient and compact heat exchangers increase, researches on estimation of two-phase flow heat transfer and pressure drop gain importance. Due to complexity of the hydrodynamic and heat transfer of the two-phase flow, there are many experimental studies available for refrigerants int he literature. In this study, a model for boiling heat transfer in a horizontal tube has been developed and the simulation results are compared with experimental ones published in the literature. In these comparisons, heat transfer coefficient is calculated by using Kattan-Thome-Favrat (1998), Shah (1982), Kandilikar (1990), Chaddock and Brunemann (1967) correlations under different operational conditions such as saturation pressure, mass flux, the type of refrigerant and two phase flow pattern. Besides that flow pattern has also been considered in the simulation by using Thome and El Hajal (2002) model. For pressure drop Lockhart-Martinelli (1949), Mueller-Steinhagen-Hack (1986) and Groennerund (1979) correlations are used in simulations. Local vapor quality change at each experimental condition through the model is determined. Roughness is an important parameter for frictional pressure drop. Friction coefficient is determined by using Churchill (1977) model. (author)

Effect of Olive Pulpe Levels in The Diet of Buffalo Calves on Physiological Body Functions and Productive Traits Under Heat Stress Conditions

International Nuclear Information System (INIS)

Gad, A.E.

2013-01-01

The present study was planned to investigate the changes that occur in growth and some physiological traits in buffalo calves as a result of using olive pulp levels (20 or 40%) under different conditions in Egypt. The study was carried out on 30 male growing buffalo calves aged 14-16 months with average body weight 309 kg and including two experiments; the 1st was carried out under mild climate in winter season on 15 calves while the 2nd was conducted during heat stress conditions of summer season on another 15 calves. In each of the two periods, animals were divided into three equal groups (5 buffalo calves in each). The first group was considered as control to olive pulp levels of 0% . The second and third groups receive olive pulp with 20 and 40% of the ingredient ration, respectively. The results showed that heat stress conditions of hot period induced significant decreases in the levels of final live body weight (FLBW), daily body weight gain (DBWG), total body weight gain (TBWG), total protein, albumin, total lipids, total cholesterol, Ca, inorganic P and thyroid hormones level (T4 and T3). On the other hand, significant increase in urea-N, creatinine, GOT and GPT as compared with animals under mild conditions was recorded. Olive pulp levels in the diet affected significantly the total body gain, daily body weight gain, total cholesterol and thyroid hormones (T4 or T3). The values were lower in the group received 40% olive pulp than in the two groups received 0 and 20.0 % olive pulp. In addition, animals received 40% olive pulp showed significant increase in urea-N, creatinine, GPT, total lipids and Ca. It could be concluded that heat stress conditions of summer period induced significant depression in daily body weight gain and changed most blood components and thyroid hormones which related to physiological functions in buffalo calves. Concerning added olive pulp to the ration of buffalo calves, it could be concluded that daily body gain of buffalo calves

Optomechanical transistor with mechanical gain

Science.gov (United States)

Zhang, X. Z.; Tian, Lin; Li, Yong

2018-04-01

We study an optomechanical transistor, where an input field can be transferred and amplified unidirectionally in a cyclic three-mode optomechanical system. In this system, the mechanical resonator is coupled simultaneously to two cavity modes. We show that it only requires a finite mechanical gain to achieve the nonreciprocal amplification. Here the nonreciprocity is caused by the phase difference between the linearized optomechanical couplings that breaks the time-reversal symmetry of this system. The amplification arises from the mechanical gain, which provides an effective phonon bath that pumps the mechanical mode coherently. This effect is analogous to the stimulated emission of atoms, where the probe field can be amplified when its frequency is in resonance with that of the anti-Stokes transition. We show that by choosing optimal parameters, this optomechanical transistor can reach perfect unidirectionality accompanied with strong amplification. In addition, the presence of the mechanical gain can result in ultralong delay in the phase of the probe field, which provides an alternative to controlling light transport in optomechanical systems.

Stability, gain, and robustness in quantum feedback networks

International Nuclear Information System (INIS)

D'Helon, C.; James, M. R.

2006-01-01

In this paper we are concerned with the problem of stability for quantum feedback networks. We demonstrate in the context of quantum optics how stability of quantum feedback networks can be guaranteed using only simple gain inequalities for network components and algebraic relationships determined by the network. Quantum feedback networks are shown to be stable if the loop gain is less than one--this is an extension of the famous small gain theorem of classical control theory. We illustrate the simplicity and power of the small gain approach with applications to important problems of robust stability and robust stabilization

Gain curves and hydrodynamic modeling for shock ignition

International Nuclear Information System (INIS)

Lafon, M.; Ribeyre, X.; Schurtz, G.

2010-01-01

Ignition of a precompressed thermonuclear fuel by means of a converging shock is now considered as a credible scheme to obtain high gains for inertial fusion energy. This work aims at modeling the successive stages of the fuel time history, from compression to final thermonuclear combustion, in order to provide the gain curves of shock ignition (SI). The leading physical mechanism at work in SI is pressure amplification, at first by spherical convergence, and by collision with the shock reflected at center during the stagnation process. These two effects are analyzed, and ignition conditions are provided as functions of the shock pressure and implosion velocity. Ignition conditions are obtained from a non-isobaric fuel assembly, for which we present a gain model. The corresponding gain curves exhibit a significantly lower ignition threshold and higher target gains than conventional central ignition.

The Aplication of Problem Based Learning Model on Heat and Temperature

OpenAIRE

Simamora, Pintor; Rotua Estomihi Pardede, Victorya

2016-01-01

This study aims to determine the effect of Problem Based Learning model to student learning outcomes on subject of Heat and Temperature. This research is quasi-experimental. Techniques that used to gain a sample is random-cluster-sampling technique that was chosen two classes as experimental and control classes. Instruments in the form of essays tests and observation sheets to measure affectivepsychomotor of students. Pretest data on both classes showed that both classes have the same ability...

Heat pumps in dairy property; Bombas de calor em propriedade leiteira

Energy Technology Data Exchange (ETDEWEB)

Baldassin Junior, Ricardo [Universidade Estadual de Campinas (FEM/UNICAMP), SP (Brazil). Fac. de Engenharia Mecanica. Planejamento de Sistemas Energeticos; Cortez, Luis Augusto Barbosa; Jordan, Rodrigo Aparecido; Ferreira, Tamara Aurora Bartholomei [Universidade Estadual de Campinas (FEAGRI/UNICAMP), SP (Brazil). Fac. de Engenharia Agricola. Dept. de Construcoes Rurais e Ambiencia; Neves Filho, Lincoln de Carmargo; Silveira Junior, Vivaldo [Universidade Estadual de Campinas (FEA/UNICAMP), SP (Brazil). Fac. de Engenharia de Alimentos

2006-07-01

Milk is a prominence product of Brazilian agriculture, with about 2/3 of the rural properties dedicated to the milkmaid cattle breeding, the second bigger flock of the world and a representative participation in the national economy. In spite of its size, the sector still suffers of low productivity, high costs, the instability of prices and technological delay, which resulted in many producers have abandoned its activities in consequence of this new competitive scenario. Nowadays, subjects as, the rational use of energy and intensive application of technology have been hardly discussed, and indicated, as important aspects to obtain high productivity gains. In this work, it is presented an evaluation of the use of energy in a milkmaid which processes cooled raw milk in Morungaba city, Sao Paulo state, Brazil, with a 1.000 liters daily production, making use of the three main processes (cooling, milking system and water heating). Aiming at to promote the rational use of energy, it was realized in this property, an adequacy in the tank milk cooler to utilize the condensation heat, of the refrigeration system, to heat cleanness water (operation according to a heat pump). Through this practical, it was objectified the exclusion of the use of the electric resistance in the heating process for term -accumulation (300 liters/day), promoting consumption reduction and rational use of energy. (author)

3-D NUMERICAL STUDY AND COMPARISON OF ECCENTRIC AND CONCENTRIC ANNULAR-FINNED TUBE HEAT EXCHANGERS

Directory of Open Access Journals (Sweden)

FAROUK TAHROUR

2015-11-01

Full Text Available The use of 3-D computational fluid dynamics (CFD is proposed to simulate the conjugate conduction-convection of heat transfer problems in eccentric annularfinned tube heat exchangers. The numerical simulation results allow us to evaluate the heat transfer coefficient over fin surfaces, the fin efficiency and the pressure drop. The aim of the present paper is to determine the optimum tube position in the circular fin that maximizes heat dissipation and minimizes pressure drop. In addition, this study analyzes the effects of fin spacing and fin tube diameter on heat transfer and flow characteristics for a range of Reynolds numbers, 4500≤Re≤22500. A satisfactory qualitative and quantitative agreement was obtained between the numerical predictions and the results published in the literature. For small fin spacings, the eccentric annular finned tube is more efficient than the concentric one. Among the cases examined, the average heat transfer coefficient of the eccentric annular-finned tube, for a tube shift St =12 mm and a Reynolds number Re = 9923, was 7.61% greater than that of the concentric one. This gain is associated with a 43.09% reduction in pressure drop.

Perception of gain in U.S.-Soviet arms control

International Nuclear Information System (INIS)

D'Anieri, P.J.

1991-01-01

Most current work in the field of international cooperation focuses on the resolution of the 'prisoners dilemma.' Such work begins by assuming that the issues under consideration are defined by absolute gains, where both sides can gain simultaneously. But the realist strand of international relations literature holds that this assumption is suspect - that international relations are usually characterized by relative gains, where gain for one side comes only at the others expense. The model developed here uses the question of absolute versus relative gains not as a theoretical assumption, but as a variable to be measured empirically. The hypothesis is that whether or not the US and the Soviet Union cooperate to limit arms competition is largely determined by whether the two sides define the issue in question as one of absolute or relative gains. The 'perception of gain' hypothesis is compared to explanations at the levels of the international system (rational choice), domestic politics, and individual belief systems. Three case studies are used to compare the strengths and weaknesses of each hypothesis. The findings confirmed that perception of gain is an important independent variable affecting arms control outcomes, but none of the theories were completely supported or rejected

Antidepressants and Weight Gain

Science.gov (United States)

... 2015;37:46. Blumenthal SR, et al. An electronic health records study of long-term weight gain following antidepressant ... your agreement to the Terms and Conditions and Privacy Policy linked below. Terms and Conditions Privacy Policy ...

Lignite chemical conversion in an indirect heat rotary kiln gasifier

Directory of Open Access Journals (Sweden)

Hatzilyberis Kostas S.

2006-01-01

Full Text Available The results on the gasification of Greek lignite using two indirect heat (allothermal pilot rotary kiln gasifiers are reported in the present work. The development of this new reactor-gasifier concept intended for solid fuels chemical conversion exploits data and experience gained from the following two pilot plants. The first unit A (about 100 kg/h raw lignite demonstrated the production of a medium heating value gas (12-13 MJ/Nm3 with quite high DAF (dry ash free coal conversions, in an indirect heat rotary gasifier under mild temperature and pressure conditions. The second unit B is a small pilot size unit (about 10 kg/h raw lignite comprises an electrically heated rotary kiln, is an operation flexible and exhibits effective phase mixing and enhanced heat transfer characteristics. Greek lignite pyrolysis and gasification data were produced from experiments performed with pilot plant B and the results are compared with those of a theoretical model. The model assumes a scheme of three consecutive-partly parallel processes (i. e. drying, pyrolysis, and gasification and predicts DAF lignite conversion and gas composition in relatively good agreement with the pertinent experimental data typical of the rotary kiln gasifier performance. Pilot plant B is currently being employed in lime-enhanced gasification studies aiming at the production of hydrogen enriched synthesis gas. Presented herein are two typical gas compositions obtain from lignite gasification runs in the presence or not of lime. .

Sound pressure gain produced by the human middle ear.

Science.gov (United States)

Kurokawa, H; Goode, R L

1995-10-01

The acoustic function of the middle ear is to match sound passing from the low impedance of air to the high impedance of cochlear fluid. Little information is available on the actual middle ear pressure gain in human beings. This article describes experiments on middle ear pressure gain in six fresh human temporal bones. Stapes footplate displacement and phase were measured with a laser Doppler vibrometer before and after removal of the tympanic membrane, malleus, and incus. Acoustic insulation of the round window with clay was performed. Umbo displacement was also measured before tympanic membrane removal to assess baseline tympanic membrane function. The middle ear has its major gain in the lower frequencies, with a peak near 0.9 kHz. The mean gain was 23.0 dB below 1.0 kHz, the resonant frequency of the middle ear; the mean peak gain was 26.6 dB. Above 1.0 kHz, the second pressure gain decreased at a rate of -8.6 dB/octave, with a mean gain of 6.5 dB at 4.0 kHz. Only a small amount of gain was present above 7.0 kHz. Significant individual differences in pressure gain were found between ears that appeared related to variations in tympanic membrane function and not to variations in cochlear impedance.

Prediction of the heat gain of external walls: An innovative approach for full-featured excitations based on the simplified method of Mackey-and-Wright

International Nuclear Information System (INIS)

Ruivo, C.R.; Vaz, D.C.

2015-01-01

Highlights: • The transient thermal behaviour of external multilayer walls of buildings is studied. • Reference results for four representative walls, obtained with a numerical model, are provided. • Shortcomings of approaches based on the Mackey-and-Wright method are identified. • Handling full-feature excitations with Fourier series decomposition improves accuracy. • A simpler, yet accurate, promising novel approach to predict heat gain is proposed. - Abstract: Nowadays, simulation tools are available for calculating the thermal loads of multiple rooms of buildings, for given inputs. However, due to inaccuracies or uncertainties in some of the input data (e.g., thermal properties, air infiltrations flow rates, building occupancy), the evaluated thermal load may represent no more than just an estimate of the actual thermal load of the spaces. Accordingly, in certain practical situations, simplified methods may offer a more reasonable trade-off between effort and results accuracy than advanced software. Hence, despite the advances in computing power over the last decades, simplified methods for the evaluation of thermal loads are still of great interest nowadays, for both the practicing engineer and the graduating student, since these can be readily implemented or developed in common computational-tools, like a spreadsheet. The method of Mackey and Wright (M&W) is a simplified method that upon values of the decrement factor and time lag of a wall (or roof) estimates the instantaneous rate of heat transfer through its indoor surface. It assumes cyclic behaviour and shows good accuracy when the excitation and response have matching shapes, but it involves non negligible error otherwise, for example, in the case of walls of high thermal inertia. The aim of this study is to develop a simplified procedure that considerably improves the accuracy of the M&W method, particularly for excitations that noticeably depart from the sinusoidal shape, while not

Heat Transfer Characteristics of SiC-coated Heat Pipe for Passive Decay Heat Removal

International Nuclear Information System (INIS)

Kim, Kyung Mo; Kim, In Guk; Jeong, Yeong Shin; Bang, In Cheol

2014-01-01

The main concern with the Fukushima accident was the failure of active and passive core cooling systems. The main function of existing passive decay heat removal systems is feeding additional coolant to the reactor core. Thus, an established emergency core cooling system (ECCS) cannot operate properly because of impossible depressurization under the station blackout (SBO) condition. Therefore, a new concept for passive decay heat removal system is required. In this study, an innovative hybrid control rod concept is considered for passive in-core decay heat removal that differs from the existing direct vessel injection core cooling system and passive auxiliary feedwater system (PAFS). The heat transfer between the evaporator and condenser sections occurs by phase change of the working fluid and capillary action induced by wick structures installed on the inner wall of the heat pipe. In this study, a hybrid control rod is developed to take the roles of both neutron absorption and heat removal by combining the functions of a heat pipe and control rod. Previous studies on enhancing the heat removal capacity of heat pipes used nanofluids, self-rewetting fluids, various wick structures and condensers. Many studies have examined the thermal performances of heat pipes using various nanofluids. They concluded that the enhanced thermal performance of the heat pipe using nanofluids is due to nanoparticle deposition on the wick structures. Thus, the wick structure of heat pipes has been modified by nanoparticle deposition to enhance the heat removal capacity. However, previous studies used relatively small heat pipes and narrow ranges of heat loads. The environment of a nuclear reactor is very specific, and the decay heat produced by fission products after shutdown is relatively large. Thus, this study tested a large-scale heat pipe over a wide range of power. The concept of a hybrid heat pipe for an advanced in-core decay heat removal system was introduced for complete

Heat Transfer Characteristics of SiC-coated Heat Pipe for Passive Decay Heat Removal

Energy Technology Data Exchange (ETDEWEB)

Kim, Kyung Mo; Kim, In Guk; Jeong, Yeong Shin; Bang, In Cheol [Ulsan National Institute of Science and Technology, Ulsan (Korea, Republic of)

2014-10-15

The main concern with the Fukushima accident was the failure of active and passive core cooling systems. The main function of existing passive decay heat removal systems is feeding additional coolant to the reactor core. Thus, an established emergency core cooling system (ECCS) cannot operate properly because of impossible depressurization under the station blackout (SBO) condition. Therefore, a new concept for passive decay heat removal system is required. In this study, an innovative hybrid control rod concept is considered for passive in-core decay heat removal that differs from the existing direct vessel injection core cooling system and passive auxiliary feedwater system (PAFS). The heat transfer between the evaporator and condenser sections occurs by phase change of the working fluid and capillary action induced by wick structures installed on the inner wall of the heat pipe. In this study, a hybrid control rod is developed to take the roles of both neutron absorption and heat removal by combining the functions of a heat pipe and control rod. Previous studies on enhancing the heat removal capacity of heat pipes used nanofluids, self-rewetting fluids, various wick structures and condensers. Many studies have examined the thermal performances of heat pipes using various nanofluids. They concluded that the enhanced thermal performance of the heat pipe using nanofluids is due to nanoparticle deposition on the wick structures. Thus, the wick structure of heat pipes has been modified by nanoparticle deposition to enhance the heat removal capacity. However, previous studies used relatively small heat pipes and narrow ranges of heat loads. The environment of a nuclear reactor is very specific, and the decay heat produced by fission products after shutdown is relatively large. Thus, this study tested a large-scale heat pipe over a wide range of power. The concept of a hybrid heat pipe for an advanced in-core decay heat removal system was introduced for complete

Compact gain saturated plasma based X-ray lasers down to 6.9nm

Science.gov (United States)

Rocca, Jorge; Wang, Y.; Wang, S.; Rockwood, A.; Berrill, M.; Shlyaptsev, V.

2017-10-01

Plasma based soft x-ray amplifiers allow many experiments requiring bright, high energy soft x-ray laser pulses to be conducted in compact facilities. We have extended the wavelength of compact gain saturated x-ray lasers to 6.89 nm in a Ni-like Gd plasma generated by a Ti:Sa laser. Gain saturated laser operation was also obtained at 7.36 nm in Ni-like Sm. Isolectronic scaling and optimization of laser pre-pulse duration allowed us to also observe strong lasing at 6.6 nm and 6.1 nm in Ni-like Tb, and amplification at 6.4 nm and 5.89 nm in Ni-like Dy. The results were obtained by transient laser heating of solid targets with traveling wave excitation at progressively increased gracing incidence angles. We show that the optimum pump angle of incidence for collisional Ni-like lasers increases linearly with atomic number from Z =42 to Z =66, reaching 43 degrees for Ni-like Dy, in good agreement with hydrodynamic/atomic physics simulations. These results will enable single-shot nano-scale imaging and other application of sub-7 nm lasers to be performed at compact facilities. Work supported by Grant DE-FG02-4ER15592 of the Department of Energy, Office of Science, and by the National Science Foundation Grant ECCS 1509925.

26 CFR 1.1374-2 - Net recognized built-in gain.

Science.gov (United States)

2010-04-01

... 26 Internal Revenue 11 2010-04-01 2010-04-01 true Net recognized built-in gain. 1.1374-2 Section 1...-in gain. (a) In general. An S corporation's net recognized built-in gain for any taxable year is the... considering only its recognized built-in gain, recognized built-in loss, and recognized built-in gain...

Optimal usage of low temperature heat sources to supply district heating by heat pumps

DEFF Research Database (Denmark)

Pieper, Henrik; Ommen, Torben Schmidt; Markussen, Wiebke Brix

2017-01-01

This paper presents a theoretical study on the optimal usage of different low temperature heat sources to supply district heating by heat pumps. The study is based on data for the Copenhagen region. The heat sources were prioritized based on the coefficient of performance calculated for each hour...... and the covered demand of each heat source as well as required peak unit capacity. The results showed that heat pumps using different heat sources yield better performance than a heat pump based on a single one. The performance was influenced by the composition of the different heat sources. It was found that 78......% groundwater, 22% seawater and 0% air resulted in highest COP of 3.33 for the given heat demand. Furthermore, the implementation of rule based short term storage made peak units redundant. The variation in base load capacity showed that heat pumps utilizing the analyzed heat sources could perform very...

Solar Heating System with Building-Integrated Heat Storage

DEFF Research Database (Denmark)

Heller, Alfred

1996-01-01

Traditional solar heating systems cover between 5 and 10% of the heat demand fordomestic hot water and comfort heating. By applying storage capacity this share can beincreased much. The Danish producer of solar heating systems, Aidt-Miljø, markets such a system including storage of dry sand heated...... by PP-pipe heat exchanger. Heat demand is reduced due to direct solar heating, and due to storage. Heat demand is reduced due to direct solar heating, due to storage and due to lower heat losses through the ground. In theory, by running the system flow backwards through the sand storage, active heating...... can be achieved.The objective of the report is to present results from measured system evaluation andcalculations and to give guidelines for the design of such solar heating systems with building integrated sand storage. The report is aimed to non-technicians. In another report R-006 the main results...

Gaining control room habitability margin at the Palisades Plant

International Nuclear Information System (INIS)

Harden, P.A.

1993-01-01

The bounding design-basis accident for control room habitability is the loss-of-coolant accident (LOCA). At Palisades, very little margin existed between the calculated control room operator thyroid dose and the 0.3-Sv (30-rem) limit of Standard Review Plan (SRP) 6.4. Also, a low rate of unfiltered air leakage into the control room during the emergency mode of operation, 5.5 x 10 -3 m 3 /s (11.6 ft 3 /min), was accounted for in the control room habitability analysis. The control room heating, ventilating and air-conditioning system at Palisades has louvered isolation dampers for the normal air intake that are exposed to a negative pressure. Considering the small margin to the thyroid dose limits and the leakage characteristics of louvered dampers, a low allowable rate of unfiltered air in-leakage raised some concern. A significant effort has been initiated to alleviate control room habitability concerns at Palisades. The first step in this effort was to evaluate the calculational models for control room habitability and gain margin through updated analytical methods. To accomplish this, a new radiological consequence analysis for the LOCA was completed

Efficiency gains, bounds, and risk in finance

NARCIS (Netherlands)

Sarisoy, Cisil

2015-01-01

This thesis consists of three chapters. The first chapter analyzes efficiency gains in the estimation of expected returns based on asset pricing models and examines the economic implications of such gains in portfolio allocation exercises. The second chapter provides nonparametric efficiency bounds

Extensive intron gain in the ancestor of placental mammals

Science.gov (United States)

2011-01-01

Background Genome-wide studies of intron dynamics in mammalian orthologous genes have found convincing evidence for loss of introns but very little for intron turnover. Similarly, large-scale analysis of intron dynamics in a few vertebrate genomes has identified only intron losses and no gains, indicating that intron gain is an extremely rare event in vertebrate evolution. These studies suggest that the intron-rich genomes of vertebrates do not allow intron gain. The aim of this study was to search for evidence of de novo intron gain in domesticated genes from an analysis of their exon/intron structures. Results A phylogenomic approach has been used to analyse all domesticated genes in mammals and chordates that originated from the coding parts of transposable elements. Gain of introns in domesticated genes has been reconstructed on well established mammalian, vertebrate and chordate phylogenies, and examined as to where and when the gain events occurred. The locations, sizes and amounts of de novo introns gained in the domesticated genes during the evolution of mammals and chordates has been analyzed. A significant amount of intron gain was found only in domesticated genes of placental mammals, where more than 70 cases were identified. De novo gained introns show clear positional bias, since they are distributed mainly in 5' UTR and coding regions, while 3' UTR introns are very rare. In the coding regions of some domesticated genes up to 8 de novo gained introns have been found. Intron densities in Eutheria-specific domesticated genes and in older domesticated genes that originated early in vertebrates are lower than those for normal mammalian and vertebrate genes. Surprisingly, the majority of intron gains have occurred in the ancestor of placentals. Conclusions This study provides the first evidence for numerous intron gains in the ancestor of placental mammals and demonstrates that adequate taxon sampling is crucial for reconstructing intron evolution. The

A wide range and high speed automatic gain control

International Nuclear Information System (INIS)

Tacconi, E.; Christiansen, C.

1993-05-01

Automatic gain control (AGC) techniques have been largely used since the beginning of electronics, but in most of the applications the dynamic response is slow compared with the carrier frequency. The problem of developing an automatic gain control with high dynamic response and wide control range simultaneously is analyzed in this work. An ideal gain control law, with the property that the total loop gain remains constant independent of the carrier amplitude, is obtained. The resulting AGC behavior is compared by computer simulations with a linear multiplier AGC. The ideal gain control law can be approximated using a transconductance amplifier. A practical circuit that has been used at CERN in the radio frequency loops of the Booster Synchrotron is presented. The circuit has high speed and 80-dB gain control range

Enhanced Gain in Photonic Crystal Amplifiers

DEFF Research Database (Denmark)

Ek, Sara; Semenova, Elizaveta; Hansen, Per Lunnemann

2012-01-01

We experimentally demonstrate enhanced gain in the slow-light regime of quantum well photonic crystal amplifiers. A strong gain enhancement is observed with the increase of the group refractive index, due to light slow-down. The slow light enhancement is shown in a amplified spontaneous emission....... These results are promising for short and efficient semiconductor optical amplifiers. This effect will also benefit other devices, such as mode locked lasers....

Warm homes: Drivers of the demand for heating in the residential sector in New Zealand

International Nuclear Information System (INIS)

Howden-Chapman, Philippa; Viggers, Helen; Chapman, Ralph; O'Dea, Des; Free, Sarah; O'Sullivan, Kimberley

2009-01-01

New Zealand houses are large, often poorly constructed and heated, by OECD standards, and consequently are colder and damper indoors than recommended by the World Health Organisation. This affects both the energy consumption and the health of households. The traditional New Zealand household pattern of only heating one room of the house has been unchanged for decades, although there has been substantial market penetration of unflued gas heaters and more recently heat pumps. This paper describes the residential sector and the results of two community-based trials of housing and heating interventions that have been designed to measure the impact of (1) retrofitting insulation and (2) replacing unflued gas heaters and electric resistance heaters with heat pumps, wood pellet burners and flued gas heaters. The paper describes findings on the rebound effect or 'take-back'-the extent to which households take the gains from insulation and heating improvements as comfort (higher temperatures) rather than energy savings, and compares energy-saving patterns with those suggested by an earlier study. Findings on these aspects of household space heating are discussed in the context of the New Zealand government's policy drive for a more sustainable energy system, and the implications for climate change policy.

Split heat pipe heat recovery system

OpenAIRE

E. Azad

2008-01-01

This paper describes a theoretical analysis of a split heat pipe heat recovery system. The analysis is based on an Effectiveness-NTU approach to deduce its heat transfer characteristics. In this study the variation of overall effectiveness of heat recovery with the number of transfer units are presented. Copyright , Manchester University Press.

Changes in job strain and subsequent weight gain

DEFF Research Database (Denmark)

Vesterlund, Gitte Kingo; Keller, Amélie Cléo; Heitmann, Berit Lilienthal

2018-01-01

in 1999 between those who were rarely v. sometimes v. often busy in 1993 (P=0·03), with the largest weight gain in individuals with sustained high busyness in both years. Loss of influence between 1993 and 1999 was associated with larger subsequent weight gain than sustained high influence (P=0......Objective: Obesity as well as job strain is increasing, and job strain might contribute to weight gain. The objective of the current study was to examine associations between longitudinal alterations in the components of job strain and subsequent weight gain. Design: The study was designed...... as a prospective cohort study with three questionnaire surveys enabling measurement of job-strain alterations over 6 years and subsequent measurements of weight gain after further 10 years of follow-up. ANCOVA and trend analyses were conducted. Job demands were measured as job busyness and speed, and control...

Characterization of Single Phase and Two Phase Heat and Momentum Transport in a Spiraling Radial Inow Microchannel Heat Sink

Science.gov (United States)

Ruiz, Maritza

Thermal management of systems under high heat fluxes on the order of hundreds of W/cm2 is important for the safety, performance and lifetime of devices, with innovative cooling technologies leading to improved performance of electronics or concentrating solar photovoltaics. A novel, spiraling radial inflow microchannel heat sink for high flux cooling applications, using a single phase or vaporizing coolant, has demonstrated enhanced heat transfer capabilities. The design of the heat sink provides an inward swirl flow between parallel, coaxial disks that form a microchannel of 1 cm radius and 300 micron channel height with a single inlet and a single outlet. The channel is heated on one side through a conducting copper surface, and is essentially adiabatic on the opposite side to simulate a heat sink scenario for electronics or concentrated photovoltaics cooling. Experimental results on the heat transfer and pressure drop characteristics in the heat sink, using single phase water as a working fluid, revealed heat transfer enhancements due to flow acceleration and induced secondary flows when compared to unidirectional laminar fully developed flow between parallel plates. Additionally, thermal gradients on the surface are small relative to the bulk fluid temperature gain, a beneficial feature for high heat flux cooling applications. Heat flux levels of 113 W/cm2 at a surface temperature of 77 deg C were reached with a ratio of pumping power to heat rate of 0.03%. Analytical models on single phase flow are used to explore the parametric trends of the flow rate and passage geometry on the streamlines and pressure drop through the device. Flow boiling heat transfer and pressure drop characteristics were obtained for this heat sink using water at near atmospheric pressure as the working fluid for inlet subcooling levels ranging from 20 to 80 deg C and mean mass flux levels ranging from 184-716 kg/m. 2s. Flow enhancements similar to singlephase flow were expected, as well

Heat cascading regenerative sorption heat pump

Science.gov (United States)

Jones, Jack A. (Inventor)

1995-01-01

A simple heat cascading regenerative sorption heat pump process with rejected or waste heat from a higher temperature chemisorption circuit (HTCC) powering a lower temperature physisorption circuit (LTPC) which provides a 30% total improvement over simple regenerative physisorption compression heat pumps when ammonia is both the chemisorbate and physisorbate, and a total improvement of 50% or more for LTPC having two pressure stages. The HTCC contains ammonia and a chemisorbent therefor contained in a plurality of canisters, a condenser-evaporator-radiator system, and a heater, operatively connected together. The LTPC contains ammonia and a physisorbent therefor contained in a plurality of compressors, a condenser-evaporator-radiator system, operatively connected together. A closed heat transfer circuit (CHTC) is provided which contains a flowing heat transfer liquid (FHTL) in thermal communication with each canister and each compressor for cascading heat from the HTCC to the LTPC. Heat is regenerated within the LTPC by transferring heat from one compressor to another. In one embodiment the regeneration is performed by another CHTC containing another FHTL in thermal communication with each compressor. In another embodiment the HTCC powers a lower temperature ammonia water absorption circuit (LTAWAC) which contains a generator-absorber system containing the absorbent, and a condenser-evaporator-radiator system, operatively connected together. The absorbent is water or an absorbent aqueous solution. A CHTC is provided which contains a FHTL in thermal communication with the generator for cascading heat from the HTCC to the LTAWAC. Heat is regenerated within the LTAWAC by transferring heat from the generator to the absorber. The chemical composition of the chemisorbent is different than the chemical composition of the physisorbent, and the absorbent. The chemical composition of the FHTL is different than the chemisorbent, the physisorbent, the absorbent, and ammonia.

Capital gains in economic theory and national accounting

Directory of Open Access Journals (Sweden)

J. STEINDL

1998-12-01

Full Text Available Capital gains are ironically one of the least studied concepts in economics despite their crucial role in national accounting. Although capital gains are technically not involved in the circular flow of production and incomes, they are a vital determinants of consumer credit and personal savings. Recent findings, in fact, correlate capital gains with the prevalence of inflationary pressures and gyrations on spending in assets.

Development and Validation of a Gas-Fired Residential Heat Pump Water Heater - Final Report

Energy Technology Data Exchange (ETDEWEB)

Michael Garrabrant; Roger Stout; Paul Glanville; Janice Fitzgerald; Chris Keinath

2013-01-21

For gas-fired residential water heating, the U.S. and Canada is predominantly supplied by minimum efficiency storage water heaters with Energy Factors (EF) in the range of 0.59 to 0.62. Higher efficiency and higher cost ($700 - $2,000) options serve about 15% of the market, but still have EFs below 1.0, ranging from 0.65 to 0.95. To develop a new class of water heating products that exceeds the traditional limit of thermal efficiency, the project team designed and demonstrated a packaged water heater driven by a gas-fired ammonia-water absorption heat pump. This gas-fired heat pump water heater can achieve EFs of 1.3 or higher, at a consumer cost of $2,000 or less. Led by Stone Mountain Technologies Inc. (SMTI), with support from A.O. Smith, the Gas Technology Institute (GTI), and Georgia Tech, the cross-functional team completed research and development tasks including cycle modeling, breadboard evaluation of two cycles and two heat exchanger classes, heat pump/storage tank integration, compact solution pump development, combustion system specification, and evaluation of packaged prototype GHPWHs. The heat pump system extracts low grade heat from the ambient air and produces high grade heat suitable for heating water in a storage tank for domestic use. Product features that include conventional installation practices, standard footprint and reasonable economic payback, position the technology to gain significant market penetration, resulting in a large reduction of energy use and greenhouse gas emissions from domestic hot water production.

Adequacy of Prenatal Care and Gestational Weight Gain

Science.gov (United States)

Crandell, Jamie L.; Jones-Vessey, Kathleen

2016-01-01

Abstract Background: The goal of prenatal care is to maximize health outcomes for a woman and her fetus. We examined how prenatal care is associated with meeting the 2009 Institute of Medicine (IOM) guidelines for gestational weight gain. Sample: The study used deidentified birth certificate data supplied by the North Carolina State Center for Health Statistics. The sample included 197,354 women (≥18 years) who delivered singleton full-term infants in 2011 and 2012. Methods: A generalized multinomial model was used to identify how adequate prenatal care was associated with the odds of gaining excessive or insufficient weight during pregnancy according to the 2009 IOM guidelines. The model adjusted for prepregnancy body size, sociodemographic factors, and birth weight. Results: A total of 197,354 women (≥18 years) delivered singleton full-term infants. The odds ratio (OR) for excessive weight gain was 2.44 (95% CI 2.37–2.50) in overweight and 2.33 (95% CI 2.27–2.40) in obese women compared with normal weight women. The OR for insufficient weight gain was 1.15 (95% CI 1.09–1.22) for underweight and 1.34 (95% CI 1.30–1.39) for obese women compared with normal weight women. Prenatal care at the inadequate or intermediate levels was associated with insufficient weight gain (OR: 1.32, 95% CI 1.27–1.38; OR: 1.15, 95% CI 1.09–1.21, respectively) compared with adequate prenatal care. Women with inadequate care were less likely to gain excessive weight (OR: 0.88, 95% CI 0.86–0.91). Conclusions: Whereas prenatal care was effective for preventing insufficient weight gain regardless of prepregnancy body size, educational background, and racial/ethnic group, there were no indications that adequate prenatal care was associated with reduced risk for excessive gestational weight gain. Further research is needed to improve prenatal care programs for preventing excess weight gain. PMID:26741198

Modeling of heat transfer into a heat pipe for a localized heat input zone

International Nuclear Information System (INIS)

Rosenfeld, J.H.

1987-01-01

A general model is presented for heat transfer into a heat pipe using a localized heat input. Conduction in the wall of the heat pipe and boiling in the interior structure are treated simultaneously. The model is derived from circumferential heat transfer in a cylindrical heat pipe evaporator and for radial heat transfer in a circular disk with boiling from the interior surface. A comparison is made with data for a localized heat input zone. Agreement between the theory and the model is good. This model can be used for design purposes if a boiling correlation is available. The model can be extended to provide improved predictions of heat pipe performance

The role of domestic biomass in electricity, heat and grid balancing markets in Switzerland

International Nuclear Information System (INIS)

Panos, Evangelos; Kannan, Ramachandran

2016-01-01

The Swiss Energy Strategy targets to reduce per capita energy consumption, to decrease the share of fossil energy and to replace nuclear electricity generation by gains in efficiency and renewable energy sources. In view of the above objectives, we evaluated the prospects of biomass in stationary applications and grid balancing from an energy system perspective. We quantify a number of “what-if” scenarios using a cost-optimisation bottom-up model, with detailed representation of biomass production and use pathways, electricity and heat sectors, and grid ancillary services markets. The scenario analysis shows that domestic biomass can contribute 5–7% in electricity and 14–21% in heat production by 2050, depending on natural gas prices and climate policy intensity. Pooling of biogenic driven cogeneration plants can provide about 22–44% of the total secondary control power in 2050. Generally, biogenic technologies complement other assets in heat, electricity and ancillary services markets such as heat pumps, new renewable sources and hydropower. - Highlights: • Development and application of the Swiss TIMES electricity and heat system model. • Bioenergy supplies 5–7% of electricity and 14–21% of heat by 2050. • Biogenic gas driven CHP can provide 22–44% of secondary control power in 2050.

Developmental Gains in Visuospatial Memory Predict Gains in Mathematics Achievement

OpenAIRE

Li, Yaoran; Geary, David C.

2013-01-01

Visuospatial competencies are related to performance in mathematical domains in adulthood, but are not consistently related to mathematics achievement in children. We confirmed the latter for first graders and demonstrated that children who show above average first-to-fifth grade gains in visuospatial memory have an advantage over other children in mathematics. The study involved the assessment of the mathematics and reading achievement of 177 children in kindergarten to fifth grade, inclusiv...

Industrial excess heat for district heating in Denmark

DEFF Research Database (Denmark)

Bühler, Fabian; Petrovic, Stefan; Karlsson, Kenneth Bernard

2017-01-01

analyses excess heat sources from the industrial sector and how they could be used for district heating. This method first allocates excess heat to single production units by introducing and validating a new approach. Spatial analysis of the heat sources and consumers are then performed to evaluate...... the potential for using them for district heating. In this way the theoretical potential of using the excess heat for covering the heating demand of buildings is determined. Through the use of industry specific temperature profiles the heat usable directly or via heat pumps is further found. A sensitivity...... analysis investigates the impact of future energy efficiency measures in the industry, buildings and the district heating grid on the national potential. The results show that for the case study of Denmark, 1.36 TWh of district heat could be provided annually with industrial excess heat from thermal...

Heating and current drive requirements towards steady state operation in ITER

Energy Technology Data Exchange (ETDEWEB)

Poli, F. M.; Kessel, C. E.; Gorelenkova, M. [Princeton Plasma Physics Laboratory, Princeton, NJ 08543 (United States); Bonoli, P. T. [MIT Plasma Science and Fusion Center, Cambridge, MA 02139 (United States); Batchelor, D. B. [Oak Ridge National Laboratory, Oak Ridge, TN 37831-6169 (United States); Harvey, B.; Petrov, Y. [CompX, Box 2672, Del Mar, CA 92014 (United States)

2014-02-12

Steady state scenarios envisaged for ITER aim at optimizing the bootstrap current, while maintaining sufficient confinement and stability to provide the necessary fusion yield. Non-inductive scenarios will need to operate with Internal Transport Barriers (ITBs) in order to reach adequate fusion gain at typical currents of 9 MA. However, the large pressure gradients associated with ITBs in regions of weak or negative magnetic shear can be conducive to ideal MHD instabilities, reducing the no-wall limit. The E × B flow shear from toroidal plasma rotation is expected to be low in ITER, with a major role in the ITB dynamics being played by magnetic geometry. Combinations of H/CD sources that maintain weakly reversed magnetic shear profiles throughout the discharge are the focus of this work. Time-dependent transport simulations indicate that, with a trade-off of the EC equatorial and upper launcher, the formation and sustainment of quasi-steady state ITBs could be demonstrated in ITER with the baseline heating configuration. However, with proper constraints from peeling-ballooning theory on the pedestal width and height, the fusion gain and the maximum non-inductive current are below the ITER target. Upgrades of the heating and current drive system in ITER, like the use of Lower Hybrid current drive, could overcome these limitations, sustaining higher non-inductive current and confinement, more expanded ITBs which are ideal MHD stable.

Heating and current drive requirements towards steady state operation in ITER

Science.gov (United States)

Poli, F. M.; Bonoli, P. T.; Kessel, C. E.; Batchelor, D. B.; Gorelenkova, M.; Harvey, B.; Petrov, Y.

2014-02-01

Steady state scenarios envisaged for ITER aim at optimizing the bootstrap current, while maintaining sufficient confinement and stability to provide the necessary fusion yield. Non-inductive scenarios will need to operate with Internal Transport Barriers (ITBs) in order to reach adequate fusion gain at typical currents of 9 MA. However, the large pressure gradients associated with ITBs in regions of weak or negative magnetic shear can be conducive to ideal MHD instabilities, reducing the no-wall limit. The E × B flow shear from toroidal plasma rotation is expected to be low in ITER, with a major role in the ITB dynamics being played by magnetic geometry. Combinations of H/CD sources that maintain weakly reversed magnetic shear profiles throughout the discharge are the focus of this work. Time-dependent transport simulations indicate that, with a trade-off of the EC equatorial and upper launcher, the formation and sustainment of quasi-steady state ITBs could be demonstrated in ITER with the baseline heating configuration. However, with proper constraints from peeling-ballooning theory on the pedestal width and height, the fusion gain and the maximum non-inductive current are below the ITER target. Upgrades of the heating and current drive system in ITER, like the use of Lower Hybrid current drive, could overcome these limitations, sustaining higher non-inductive current and confinement, more expanded ITBs which are ideal MHD stable.

Quantifying the mechanisms of domain gain in animal proteins.

Science.gov (United States)

Buljan, Marija; Frankish, Adam; Bateman, Alex

2010-01-01

Protein domains are protein regions that are shared among different proteins and are frequently functionally and structurally independent from the rest of the protein. Novel domain combinations have a major role in evolutionary innovation. However, the relative contributions of the different molecular mechanisms that underlie domain gains in animals are still unknown. By using animal gene phylogenies we were able to identify a set of high confidence domain gain events and by looking at their coding DNA investigate the causative mechanisms. Here we show that the major mechanism for gains of new domains in metazoan proteins is likely to be gene fusion through joining of exons from adjacent genes, possibly mediated by non-allelic homologous recombination. Retroposition and insertion of exons into ancestral introns through intronic recombination are, in contrast to previous expectations, only minor contributors to domain gains and have accounted for less than 1% and 10% of high confidence domain gain events, respectively. Additionally, exonization of previously non-coding regions appears to be an important mechanism for addition of disordered segments to proteins. We observe that gene duplication has preceded domain gain in at least 80% of the gain events. The interplay of gene duplication and domain gain demonstrates an important mechanism for fast neofunctionalization of genes.

Effects of having a baby on weight gain.

Science.gov (United States)

Brown, Wendy J; Hockey, Richard; Dobson, Annette J

2010-02-01

Women often blame weight gain in early adulthood on having a baby. The aim was to estimate the weight gain attributable to having a baby, after disentangling the effects of other factors that influence weight change at this life stage. A longitudinal study of a randomly selected cohort of 6458 Australian women, aged 18-23 years in 1996, was conducted. Self-report mailed surveys were completed in 1996, 2000, 2003, and 2006, and data were analyzed in 2008. On average, women gained weight at the rate of 0.93% per year (95% CI=0.89, 0.98) or 605 g/year (95% CI=580, 635) for a 65-kg woman. Over the 10-year study period, partnered women with one baby gained almost 4 kg more, and those with a partner but no baby gained 1.8 kg more, than unpartnered childless women (after adjustment for other significant factors: initial BMI and age; physical activity, sitting time, energy intake (2003); education level, hours in paid work, and smoking). Having a baby has a marked effect on 10-year weight gain, but there is also an effect attributable to getting married or living with a partner. Social and lifestyle as well as energy balance variables should be considered when developing strategies to prevent weight gain in young adult women. Copyright 2010 American Journal of Preventive Medicine. Published by Elsevier Inc. All rights reserved.

Design of serially connected district heating heat pumps utilising a geothermal heat source

DEFF Research Database (Denmark)

Jensen, Jonas Kjær; Ommen, Torben Schmidt; Markussen, Wiebke Brix

2017-01-01

The design of two heat pumps (HP), connected in series, was investigated for operation in the district heating (DH) network of the Greater Copenhagen area, Denmark. The installation was dimensioned to supply 7.2 MW of heat at a temperature of 85 °C. The heat pumps utilise a geothermal heat source...

Utilising heat from nuclear waste for space heating

International Nuclear Information System (INIS)

Deacon, D.

1982-01-01

A heating unit utilising the decay heat from irradiated material comprises a storage envelope for the material associated with a heat exchange system, means for producing a flow of air over the heat exchange system to extract heat from the material, an exhaust duct capable of discharging the heated air to the atmosphere, and means for selectively diverting at least some of the heated air to effect the required heating. With the flow of air over the heat exchange system taking place by a natural thermosyphon process the arrangement is self regulating and inherently reliable. (author)

Assessment of learning gains in a flipped biochemistry classroom.

Science.gov (United States)

Ojennus, Deanna Dahlke

2016-01-01

The flipped classroom has become an increasingly popular pedagogical approach to teaching and learning. In this study, learning gains were assessed in a flipped biochemistry course and compared to gains in a traditional lecture. Although measured learning gains were not significantly different between the two courses, student perception of learning gains did differ and indicates a higher level of satisfaction with the flipped lecture format. © 2015 The International Union of Biochemistry and Molecular Biology.

Ultra-high gain diffusion-driven organic transistor

Science.gov (United States)

Torricelli, Fabrizio; Colalongo, Luigi; Raiteri, Daniele; Kovács-Vajna, Zsolt Miklós; Cantatore, Eugenio

2016-01-01

Emerging large-area technologies based on organic transistors are enabling the fabrication of low-cost flexible circuits, smart sensors and biomedical devices. High-gain transistors are essential for the development of large-scale circuit integration, high-sensitivity sensors and signal amplification in sensing systems. Unfortunately, organic field-effect transistors show limited gain, usually of the order of tens, because of the large contact resistance and channel-length modulation. Here we show a new organic field-effect transistor architecture with a gain larger than 700. This is the highest gain ever reported for organic field-effect transistors. In the proposed organic field-effect transistor, the charge injection and extraction at the metal–semiconductor contacts are driven by the charge diffusion. The ideal conditions of ohmic contacts with negligible contact resistance and flat current saturation are demonstrated. The approach is general and can be extended to any thin-film technology opening unprecedented opportunities for the development of high-performance flexible electronics. PMID:26829567

Renyi information gain on quantum key

International Nuclear Information System (INIS)

Brandt, Howard E

2007-01-01

The concept of maximum Renyi information gain from quantum key is important in eavesdropping and security analyses of quantum key distribution. It is particularly useful in the design optimization of eavesdropping probes. The present work reviews the quantitative measure of Renyi information gain, its optimization, and application to the design of eavesdropping probes in which single-photon probe states become optimally entangled with the signal states on their way between the legitimate transmitter and receiver

Heat pumps in district heating networks

DEFF Research Database (Denmark)

Ommen, Torben Schmidt; Markussen, Wiebke Brix; Elmegaard, Brian

constraints limit the power plants. Efficient heat pumps can be used to decouple the constraints of electricity and heat production, while maintaining the high energy efficiency needed to match the politically agreed carbon emission goals. The requirements in terms of COP, location, capacity and economy...... and strategic planning in the energy sector. The paper presents a case study of optimal implementation of heat pumps in the present energy system of the Copenhagen area. By introduction of the correct capacity of heat pumps, a 1,6 % reduction in fuel consumption for electricity and heat production can...

Experimental device for the residential heating with heat pipe and electric heat storage blocks

Energy Technology Data Exchange (ETDEWEB)

Vasiliev, L L; Boldak, I M; Domorod, L S; Rabetsky, M I; Schirokov, E I [AN Belorusskoj SSR, Minsk (Belarus). Inst. Teplo- i Massoobmena

1992-01-01

Residential heating using electric heat storage blocks nowadays is an actual problem from the point of view of heat recovery and nature protection. In the Luikov Heat and Mass Transfer Institute a new residential electrical heater capable of heating chambers by controlling air temperature and heat output using heat pipes and an electric heat storage block was developed. This heater (BETA) is fed from the source of energy and during 7 h of night time accumulates energy sufficiently to heat 10 m{sup 3} during 24 h. Heating device BETA has a ceramic thermal storage block, electric heaters and a heat pipe with evaporator inside the ceramic block and constant temperature (65{sup o}C) finned condenser outside it. The condenser temperature could be controlled easily. BETA is compact, has high thermal response, accurate air temperature control and safe operation. Such types of residential heaters are necessary for heating residential and office building in the Mogilev and Gomel regions in Byelorussia which suffered after the Chernobyl catastrophe. (Author).

A comparison of two low grade heat recovery options

International Nuclear Information System (INIS)

Walsh, Conor; Thornley, Patricia

2013-01-01

Low grade heat (LGH) recovery is one way of increasing industrial energy efficiency and reducing associated greenhouse gas emissions. The organic Rankine cycle (ORC) and condensing boiler are two options that can be used to recover low grade heat ( 2 annually, but the high carbon intensity of the coking process means this has a negligible influence (<1%) on the overall process lifecycle impacts. However, if the electricity generated offsets the external purchasing of electricity this results in favourable economic payback periods of between 3 and 6 years. The operation of a condensing boiler within a woodchip boiler reduces the fuel required to achieve an increased thermal output. The thermal efficiency gains reduce the lifecycle impacts by between 11 and 21%, and reflect payback periods as low as 1.5–2 years, depending on the condenser type and wood supply chain. The two case studies are used to highlight the difficulty in identifying LGH recovery solutions that satisfy multiple environmental, economic and wider objectives

Solar heat storages in district heating networks

Energy Technology Data Exchange (ETDEWEB)

Ellehauge, K. (Ellehauge og Kildemoes, AArhus (DK)); Engberg Pedersen, T. (COWI A/S, Kgs. Lyngby (DK))

2007-07-15

This report gives information on the work carried out and the results obtained in Denmark on storages for large solar heating plants in district heating networks. Especially in Denmark the share of district heating has increased to a large percentage. In 1981 around 33% of all dwellings in DK were connected to a district heating network, while the percentage in 2006 was about 60% (in total 1.5 mio. dwellings). In the report storage types for short term storage and long term storages are described. Short term storages are done as steel tanks and is well established technology widely used in district heating networks. Long term storages are experimental and used in connection with solar heating. A number of solar heating plants have been established with either short term or long term storages showing economy competitive with normal energy sources. Since, in the majority of the Danish district heating networks the heat is produced in co-generation plants, i.e. plants producing both electricity and heat for the network, special attention has been put on the use of solar energy in combination with co-generation. Part of this report describes that in the liberalized electricity market central solar heating plants can also be advantageous in combination with co-generation plants. (au)

DNA gains at 8q23.2

DEFF Research Database (Denmark)

da Silva Veiga, Luciana Caricati; Bérgamo, Nádia Aparecida; dos Reis, Patrícia Pintor

2003-01-01

Gains or amplifications involving chromosome arm 8q are one of the most recurrent chromosomal alterations in head and neck tumors. To characterize previously reported gains, we performed fluorescence in situ hybridization (FISH) using the sequences BAC RP1179E1 and 8-centromere PMJ 128 as probes....

Passive annual heat storage principles in earth sheltered housing, a supplementary energy saving system in residential housing

Energy Technology Data Exchange (ETDEWEB)

Anselm, Akubue Jideofor [Green Architecture Department, School of Architecture and Urban Planning, Huazhong University of Science and Technology, Wuhan 430074 (China)

2008-07-01

This paper looks through the many benefits of earth not only as a building element in its natural form but as a building mass, energy pack and spatial enclosure which characterized by location, unique physical terrain and climatic factors can be utilized in developing housing units that will provide the needed benefits of comfort alongside the seasons. Firstly the study identifies existing sunken earth houses in the North-west of China together with identifying the characters that formed the ideas behind the choice of going below the ground. Secondly, the study examines the pattern of heat exchange, heat gains and losses as to identify the principles that makes building in earth significant as an energy conservation system. The objective of this, is to relate the ideas of sunken earth home design with such principles as the passive annual heat storage systems (PAHS) in producing houses that will serve as units used to collect free solar heat all summer and cools passively while heating the earth around it and also keeping warm in winter by retrieving heat from the soil while utilizing the free solar heat stored throughout the summer as a year-round natural thermal resource. (author)

Automation of heating system with heat pump

OpenAIRE

Ferdin, Gašper

2016-01-01

Because of high prices of energy, we are upgrading our heating systems with newer, more fuel efficient heating devices. Each new device has its own control system, which operates independently from other devices in a heating system. With a relatively low investment costs in automation, we can group devices in one central control system and increase the energy efficiency of a heating system. In this project, we show how to connect an oil furnace, a sanitary heat pump, solar panels and a heat p...

Regenerative heat sources for heating networks

International Nuclear Information System (INIS)

Huenges, Ernst; Sperber, Evelyn; Eggers, Jan-Bleicke; Noll, Florian; Kallert, Anna Maria; Reuss, Manfred

2015-01-01

The ambitious goal, the German Federal Government has set itself, to reduce the emissions of greenhouse gases by 80% to 95% by the year 2050. As there are currently more than half of German energy consumption for the production of heat is required, big contributions to climate protection can be expected from this area if more renewable heat sources are used. Renewable heat sources such as bioenergy, solar thermal and geothermal energy in particular can be provided as compared to fossil fuels with significantly lower specific CO 2 emissions. Objectives in the heating market and scenarios for the transformation of the heat sector have been elaborated in the BMU Lead Study 2011. The main pillar of this scenario is the reduction of final energy consumption for heat by the energy-efficient renovation of existing buildings and further increasing demands on the energetic quality of new buildings. To cover the remaining energy demand, a focus is on the expansion of heating networks based on renewable energies. [de

Gain maximization in a probabilistic entanglement protocol

Science.gov (United States)

di Lorenzo, Antonio; Esteves de Queiroz, Johnny Hebert

Entanglement is a resource. We can therefore define gain as a monotonic function of entanglement G (E) . If a pair with entanglement E is produced with probability P, the net gain is N = PG (E) - (1 - P) C , where C is the cost of a failed attempt. We study a protocol where a pair of quantum systems is produced in a maximally entangled state ρm with probability Pm, while it is produced in a partially entangled state ρp with the complementary probability 1 -Pm . We mix a fraction w of the partially entangled pairs with the maximally entangled ones, i.e. we take the state to be ρ = (ρm + wUlocρpUloc+) / (1 + w) , where Uloc is an appropriate unitary local operation designed to maximize the entanglement of ρ. This procedure on one hand reduces the entanglement E, and hence the gain, but on the other hand it increases the probability of success to P =Pm + w (1 -Pm) , therefore the net gain N may increase. There may be hence, a priori, an optimal value for w, the fraction of failed attempts that we mix in. We show that, in the hypothesis of a linear gain G (E) = E , even assuming a vanishing cost C -> 0 , the net gain N is increasing with w, therefore the best strategy is to always mix the partially entangled states. Work supported by CNPq, Conselho Nacional de Desenvolvimento Científico e Tecnológico, proc. 311288/2014-6, and by FAPEMIG, Fundação de Amparo à Pesquisa de Minas Gerais, proc. IC-FAPEMIG2016-0269 and PPM-00607-16.

A Brief History of Fire, Heat and Their Manifestations in Remote Sensing

Science.gov (United States)

Alavipanah, S. K.; Attarchi, S.

2015-12-01

The discovery of fire was one of the earliest of human discoveries. At the beginning, man sensed heat on his skin and then perceived the concept of fire and temperature. Fire and its manifestation in form of light and heat have contributed in many literary sources and religious books. It has being interpreted in various manners and construed by different explanations. Some of these definitions have resemblances with today's human findings in the argument about heat, temperature, light and their spectra. In this work, we reviewed a broad range of literary, historical, religious and cultural sources to gain deeper insight into the meaning of fire and heat in human's thought, beliefs and myths from the past to today. We found a close linkage between predecessor's perception and impression about heat and what is known today as thermal energy. It should be mentioned that we strictly deny the claim of their awareness of modern concepts such as energy or thermodynamics. However, we interfere that they perceived these conceptions. We cannot clearly explain how our predecessor shaped their impression about fire and heat without any knowledge of the nature of new science such as energy, temperature and thermal remote sensing. Nevertheless, their though compromise with modern science. According to the recent findings, temperature play important role as an efficient indicator of sustainability in landscape. Magnitude and distribution of temperature and its changes over time - which could be traced by thermal remote sensing- are of great importance. A concise literature review relating to fire and heat will broaden our knowledge about temperature and thermal remote sensing.

L2-gain and passivity techniques in nonlinear control

CERN Document Server

van der Schaft, Arjan

2017-01-01

This standard text gives a unified treatment of passivity and L2-gain theory for nonlinear state space systems, preceded by a compact treatment of classical passivity and small-gain theorems for nonlinear input-output maps. The synthesis between passivity and L2-gain theory is provided by the theory of dissipative systems. Specifically, the small-gain and passivity theorems and their implications for nonlinear stability and stabilization are discussed from this standpoint. The connection between L2-gain and passivity via scattering is detailed. Feedback equivalence to a passive system and resulting stabilization strategies are discussed. The passivity concepts are enriched by a generalised Hamiltonian formalism, emphasising the close relations with physical modeling and control by interconnection, and leading to novel control methodologies going beyond passivity. The potential of L2-gain techniques in nonlinear control, including a theory of all-pass factorizations of nonlinear systems, and of parametrization...

Unconventional modes in lasers with spatially varying gain and loss

International Nuclear Information System (INIS)

Ge Li; Tuereci, H. E.; Chong, Y. D.; Stone, A. D.; Rotter, S.

2011-01-01

We discuss a class of lasing modes created by a spatially inhomogeneous gain profile. These lasing modes are ''extra modes,'' in addition to, and very different from, conventional lasing modes, which arise from the passive cavity resonances. These new modes do not have high intensity across the entire gain region, but instead are localized at the gain boundary and throughout the gain-free region. They are surface modes, originating from the transmission resonances of the gain-free region. Using an S-matrix description we connect these surface modes to the lasing modes in PT-symmetric (balanced gain-loss) cavities.

Maternal Obesity, Gestational Weight Gain, and Asthma in Offspring.

Science.gov (United States)

Polinski, Kristen J; Liu, Jihong; Boghossian, Nansi S; McLain, Alexander C

2017-11-09

Obesity is common among women of childbearing age; intrauterine exposure to maternal obesity or gestational weight gain may influence the development of asthma in early childhood. We examined the relationships of maternal obesity and gestational weight gain with asthma in offspring. We used data from the Early Childhood Longitudinal Study-Birth Cohort, which has a nationally representative sample of children followed from birth in 2001 through age 4 (n = 6,450). Asthma was based on parental report of a medical professional's diagnosis. We used generalized estimating equation binomial models to compute adjusted odds ratios (ORs) of childhood asthma with maternal obesity and 4 measures of gestational weight gain. Compared with children of normal-weight mothers, children of obese mothers had increased risk of asthma (adjusted OR, 1.63; 95% confidence interval [CI], 1.26-2.12) by age 4, and children born to overweight mothers had similar risk (adjusted OR, 1.25; 95% CI, 0.99-1.59). Extreme-low weight gain (gain (≥25 kg) were associated with increased risk of asthma; however, the following measures were not significant predictors of asthma: meeting gestational weight gain recommendations of the Institute of Medicine, total gestational weight gain, and weekly rate of weight gain in the second and third trimesters. Extreme-low or extreme-high gestational weight gain and maternal obesity are risk factors for early childhood asthma, further evidence of the long-term impact of intrauterine exposure on children and the need to target preconception care to improve child health indicators.

TCAD simulation of Low Gain Avalanche Detectors

Science.gov (United States)

Dalal, Ranjeet; Jain, Geetika; Bhardwaj, Ashutosh; Ranjan, Kirti

2016-11-01

In the present work, detailed simulation using Technology Computer Aided Design (TCAD) tool, Silvaco for non-irradiated and irradiated LGAD (Low Gain Avalanche Detector) devices has been carried out. The effects of different design parameters and proton irradiation on LGAD operation are discussed in detail. An already published effective two trap bulk damage model is used to simulate the radiation damage without implementing any acceptor removal term. The TCAD simulation for irradiated LGAD devices produce decreasing gain with increasing fluence, similar to the measurement results. The space charge density and electric field distribution are used to illustrate the possible reasons for the degradation of gain of the irradiated LGAD devices.

TCAD simulation of Low Gain Avalanche Detectors

Energy Technology Data Exchange (ETDEWEB)

Dalal, Ranjeet; Jain, Geetika; Bhardwaj, Ashutosh, E-mail: ashutosh.bhardwaj@cern.ch; Ranjan, Kirti

2016-11-11

In the present work, detailed simulation using Technology Computer Aided Design (TCAD) tool, Silvaco for non-irradiated and irradiated LGAD (Low Gain Avalanche Detector) devices has been carried out. The effects of different design parameters and proton irradiation on LGAD operation are discussed in detail. An already published effective two trap bulk damage model is used to simulate the radiation damage without implementing any acceptor removal term. The TCAD simulation for irradiated LGAD devices produce decreasing gain with increasing fluence, similar to the measurement results. The space charge density and electric field distribution are used to illustrate the possible reasons for the degradation of gain of the irradiated LGAD devices.

TCAD simulation of Low Gain Avalanche Detectors

International Nuclear Information System (INIS)

Dalal, Ranjeet; Jain, Geetika; Bhardwaj, Ashutosh; Ranjan, Kirti

2016-01-01

In the present work, detailed simulation using Technology Computer Aided Design (TCAD) tool, Silvaco for non-irradiated and irradiated LGAD (Low Gain Avalanche Detector) devices has been carried out. The effects of different design parameters and proton irradiation on LGAD operation are discussed in detail. An already published effective two trap bulk damage model is used to simulate the radiation damage without implementing any acceptor removal term. The TCAD simulation for irradiated LGAD devices produce decreasing gain with increasing fluence, similar to the measurement results. The space charge density and electric field distribution are used to illustrate the possible reasons for the degradation of gain of the irradiated LGAD devices.

Energetic and exergetic analysis of waste heat recovery systems in the cement industry

International Nuclear Information System (INIS)

Karellas, S.; Leontaritis, A.-D.; Panousis, G.; Bellos, E.; Kakaras, E.

2013-01-01

In a typical cement producing procedure, 25% of the total energy used is electricity and 75% is thermal energy. However, the process is characterized by significant heat losses mainly by the flue gases and the ambient air stream used for cooling down the clinker (about 35%–40% of the process heat loss). Approximately 26% of the heat input to the system is lost due to dust, clinker discharge, radiation and convection losses from the kiln and the preheaters. A heat recovery system could be used to increase the efficiency of the cement plant and thus contribute to emissions decrease. The aim of this paper is to examine and compare energetically and exergetically, two different WHR (waste heat recovery) methods: a water-steam Rankine cycle, and an Organic Rankine Cycle (ORC). A parametric study proved that the water steam technology is more efficient than ORC in exhaust gases temperature higher than 310 °C. Finally a brief economic assessment of the most efficient solution was implemented. WHR installations in cement industry can contribute significantly in the reduction of the electrical consumptions operating cost thus being a very attractive investment with a payback period up to 5 years. - Highlights: • This paper presents waste heat recovery as a way to gain energy from the exhaust gases in a cement plant. • Water steam cycle and ORC has been analyzed for waste heat recovery. • The energetic and exergetic evaluation of the two waste heat recovery processes is presented and compared

Heat pipes for ground heating and cooling

Energy Technology Data Exchange (ETDEWEB)

Vasiliev, L L

1988-01-01

Different versions of heat pipe ground heating and cooling devices are considered. Solar energy, biomass, ground stored energy, recovered heat of industrial enterprises and ambient cold air are used as energy and cold sources. Heat pipe utilization of air in winter makes it possible to design accumulators of cold and ensures deep freezing of ground in order to increase its mechanical strength when building roadways through the swamps and ponds in Siberia. Long-term underground heat storage systems are considered, in which the solar and biomass energy is accumulated and then transferred to heat dwellings and greenhouses, as well as to remove snow from roadways with the help of heat pipes and solar collectors.

Gain tuning and fidelity in continuous-variable quantum teleportation

International Nuclear Information System (INIS)

Ide, Toshiki; Hofmann, Holger F.; Furusawa, Akira; Kobayashi, Takayoshi

2002-01-01

The fidelity of continuous-variable teleportation can be optimized by changing the gain in the modulation of the output field. We discuss the gain dependence of fidelity for coherent, vacuum, and one-photon inputs and propose optimal gain tuning strategies for corresponding input selections

Effect of heated length on the Critical Heat Flux of subcooled flow boiling. 2. Effective heated length under axially nonuniform heating condition

International Nuclear Information System (INIS)

Kinoshita, Hidetaka; Yoshida, Takuya; Nariai, Hideki; Inasaka, Fujio

1998-01-01

Effect of heated length on the Critical Heat Flux (CHF) of subcooled flow boiling with water was experimentally investigated by using direct current heated tube made of stainless steel a part of whose wall thickness was axially cut for realizing nonuniform heat flux condition. The higher enhancement of the CHF was derived for shorter tube length. The effective heated length was determined for the tube under axially nonuniform heat flux condition. When the lower heat flux part below the Net Vapor Generation (NVG) heat flux exists at the middle of tube length, then the effective heated length becomes the tube length downstream the lower heat flux parts. However, when the lower heat flux part is above the NVG, then the effective heated length is full tube length. (author)

Exergy analysis of an integrated solid oxide fuel cell and organic Rankine cycle for cooling, heating and power production

Science.gov (United States)

Al-Sulaiman, Fahad A.; Dincer, Ibrahim; Hamdullahpur, Feridun

The study examines a novel system that combined a solid oxide fuel cell (SOFC) and an organic Rankine cycle (ORC) for cooling, heating and power production (trigeneration) through exergy analysis. The system consists of an SOFC, an ORC, a heat exchanger and a single-effect absorption chiller. The system is modeled to produce a net electricity of around 500 kW. The study reveals that there is 3-25% gain on exergy efficiency when trigeneration is used compared with the power cycle only. Also, the study shows that as the current density of the SOFC increases, the exergy efficiencies of power cycle, cooling cogeneration, heating cogeneration and trigeneration decreases. In addition, it was shown that the effect of changing the turbine inlet pressure and ORC pump inlet temperature are insignificant on the exergy efficiencies of the power cycle, cooling cogeneration, heating cogeneration and trigeneration. Also, the study reveals that the significant sources of exergy destruction are the ORC evaporator, air heat exchanger at the SOFC inlet and heating process heat exchanger.

Heat Roadmap Europe: Identifying strategic heat synergy regions

International Nuclear Information System (INIS)

Persson, U.; Möller, B.; Werner, S.

2014-01-01

This study presents a methodology to assess annual excess heat volumes from fuel combustion activities in energy and industry sector facilities based on carbon dioxide emission data. The aim is to determine regional balances of excess heat relative heat demands for all third level administrative regions in the European Union (EU) and to identify strategic regions suitable for large-scale implementation of district heating. The approach is motivated since the efficiency of current supply structures to meet building heat demands, mainly characterised by direct use of primary energy sources, is low and improvable. District heating is conceived as an urban supply side energy efficiency measure employable to enhance energy system efficiency by increased excess heat recoveries; hereby reducing primary energy demands by fuel substitution. However, the importance of heat has long been underestimated in EU decarbonisation strategies and local heat synergies have often been overlooked in energy models used for such scenarios. Study results indicate that 46% of all excess heat in EU27, corresponding to 31% of total building heat demands, is located within identified strategic regions. Still, a realisation of these rich opportunities will require higher recognition of the heat sector in future EU energy policy. - Highlights: • EU27 energy and industry sector heat recycling resources are mapped and quantified. • Target regions for large-scale implementation of district heating are identified. • 46% of total EU27 excess heat volume is seized in 63 strategic heat synergy regions. • Large urban zones have lead roles to play in transition to sustainability in Europe. • Higher recognition of heat sector is needed in future EU energy policy for realisation

Practical versus theoretical domestic energy consumption for space heating

International Nuclear Information System (INIS)

Audenaert, A.; Briffaerts, K.; Engels, L.

2011-01-01

Methods to calculate the theoretical energy consumption consider several things: the number of degree days per year that need to be compensated by heating, the characteristics of the dwelling, the number of occupants and the characteristics of the installation for space heating and sanitary hot water. However, these methods do not take into account consumer behaviour, which may affect the actual consumption. The theoretical calculation methods are based on assumptions and use a number of standardized parameters. The difference between the actual and the theoretical energy consumption, and the impact of the residents' behaviour on energy consumption, is analysed by means of a literature study and a practical research. An energy advice procedure (EAP) audit is executed in five dwellings, as well as a survey regarding the energy related behaviour of the households. The theoretically calculated consumption is compared with the billed actual energy consumption of the families. The results show some problems with the current procedure and give some options to improve it. Some research needs are identified to gain more insights in the influence of different behavioural factors on the actual energy use for heating. - Highlights: → The energy advice procedure (EAP) calculates the energy use for heating in dwellings. → Calculations are compared with the real energy use for 5 dwellings. → A survey on the occupants' behaviour is used to interpret the observed differences. → Default values used in the EAP can be very different from the observed behaviour.

An analysis of heating fuel market behavior, 1989--1990

Energy Technology Data Exchange (ETDEWEB)

1990-06-01

The purpose of this report is to fully assess the heating fuel crisis from a broader and longer-term perspective. Using EIA final, monthly data, in conjunction with credible information from non-government sources, the pricing phenomena exhibited by heating fuels in late December 1989 and early January 1990 are described and evaluated in more detail and more accurately than in the interim report. Additionally, data through February 1990 (and, in some cases, preliminary figures for March) make it possible to assess the market impact of movements in prices and supplies over the heating season as a whole. Finally, the longer time frame and the availability of quarterly reports filed with the Securities and Exchange Commission make it possible to weigh the impact of revenue gains in December and January on overall profits over the two winter quarters. Some of the major, related issues raised during the House and Senate hearings in January concerned the structure of heating fuel markets and the degree to which changes in this structure over the last decade may have influenced the behavior and financial performance of market participants. Have these markets become more concentrated Was collusion or market manipulation behind December's rising prices Did these, or other, factors permit suppliers to realize excessive profits What additional costs were incurred by consumers as a result of such forces These questions, and others, are addressed in the course of this report.

Practical versus theoretical domestic energy consumption for space heating

Energy Technology Data Exchange (ETDEWEB)

Audenaert, A., E-mail: amaryllis.audenaert@artesis.be [Department of Applied Engineering: Construction, Artesis University College of Antwerp, Paardenmarkt 92, B-2000 Antwerp (Belgium); Department of Environment, Technology and Technology Management, University of Antwerp, Prinsstraat 13, B-2000 Antwerp (Belgium); Briffaerts, K. [Unit Transition Energy and Environment, VITO NV, Boeretang 200, B-2400 Mol (Belgium); Engels, L. [Department of Applied Engineering: Construction, Artesis University College of Antwerp, Paardenmarkt 92, B-2000 Antwerp (Belgium)

2011-09-15

Methods to calculate the theoretical energy consumption consider several things: the number of degree days per year that need to be compensated by heating, the characteristics of the dwelling, the number of occupants and the characteristics of the installation for space heating and sanitary hot water. However, these methods do not take into account consumer behaviour, which may affect the actual consumption. The theoretical calculation methods are based on assumptions and use a number of standardized parameters. The difference between the actual and the theoretical energy consumption, and the impact of the residents' behaviour on energy consumption, is analysed by means of a literature study and a practical research. An energy advice procedure (EAP) audit is executed in five dwellings, as well as a survey regarding the energy related behaviour of the households. The theoretically calculated consumption is compared with the billed actual energy consumption of the families. The results show some problems with the current procedure and give some options to improve it. Some research needs are identified to gain more insights in the influence of different behavioural factors on the actual energy use for heating. - Highlights: > The energy advice procedure (EAP) calculates the energy use for heating in dwellings. > Calculations are compared with the real energy use for 5 dwellings. > A survey on the occupants' behaviour is used to interpret the observed differences. > Default values used in the EAP can be very different from the observed behaviour.

A Comparative Proteomic Analysis of Pinellia ternata Leaves Exposed to Heat Stress

Directory of Open Access Journals (Sweden)

Zuoyi Liu

2013-10-01

Full Text Available Pinellia ternata is an important traditional Chinese medicinal plant. The growth of P. ternata is sensitive to high temperatures. To gain a better understanding of heat stress responses in P. ternata, we performed a comparative proteomic analysis. P. ternata seedlings were subjected to a temperature of 38 °C and samples were collected 24 h after treatment. Increased relative ion leakage and lipid peroxidation suggested that oxidative stress was frequently generated in rice leaves exposed to high temperature. Two-dimensional electrophoresis (2-DE was used to analyze heat-responsive proteins. More than 600 protein spots were reproducibly detected on each gel; of these spots, 20 were up-regulated, and 7 were down-regulated. A total of 24 proteins and protein species were successfully identified by MALDI-TOF/TOF MS. These proteins and protein species were found to be primarily small heat shock proteins (58% as well as proteins involved in RNA processing (17%, photosynthesis (13%, chlorophyll biosynthetic processes (4%, protein degradation (4% and defense (4%. Using 2-DE Western blot analysis, we confirmed the identities of the cytosolic class II small heat shock protein (sHSPs-CII identified by MS. The expression levels of four different proteins [cytosolic class I small heat shock protein (sHSPs-CI, sHSPs-CII, mitochondrial small heat shock protein (sHSPs-MIT, glycine-rich RNA-binding protein (GRP] were analyzed at the transcriptional level by quantitative real-time PCR. The mRNA levels of three sHSPs correlated with the corresponding protein levels. However, GRP was down-regulated at the beginning of heat stress but then increased substantially to reach a peak after 24 h of heat stress. Our study provides valuable new insight into the responses of P. ternata to heat stress.

Waste heat recovery from the exhaust of a diesel generator using Rankine Cycle

International Nuclear Information System (INIS)

Hossain, Shekh Nisar; Bari, Saiful

2013-01-01

Highlights: • Diesel engine exhaust contains 40% energy which can be used to produce extra power. • Extra 11% power gained with optimized heat exchangers using water as working fluid. • As a result brake specific fuel consumption improved by 12%. • Parallel arrangement of heat exchangers showed better performance than series. • Optimum working fluid pressure varies with the engine power. - Abstract: Exhaust heat from diesel engines can be an important heat source to provide additional power using a separate Rankine Cycle (RC). In this research, experiments were conducted to measure the available exhaust heat from a 40 kW diesel generator using two ‘off-the-shelf’ heat exchangers. The effectiveness of the heat exchangers using water as the working fluid was found to be 0.44 which seems to be lower than a standard one. This lower performance of the existing heat exchangers indicates the necessity of optimization of the design of the heat exchangers for this particular application. With the available experimental data, computer simulations were carried out to optimize the design of the heat exchangers. Two heat exchangers were used to generate super-heated steam to expand in the turbine using two orientations: series and parallel. The optimized heat exchangers were then used to estimate additional power considering actual turbine isentropic efficiency. The proposed heat exchanger was able to produce 11% additional power using water as the working fluid at a pressure of 15 bar at rated engine load. This additional power resulted into 12% improvement in brake-specific fuel consumption (bsfc). The effects of the working fluid pressure were also investigated to maximize the additional power production. The pressure was limited to 15 bar which was constrained by the exhaust gas temperature. However, higher pressure is possible for higher exhaust gas temperatures from higher capacity engines. This would yield more additional power with further improvements in

Sleeve Push Technique: A Novel Method of Space Gaining.

Science.gov (United States)

Verma, Sanjeev; Bhupali, Nameksh Raj; Gupta, Deepak Kumar; Singh, Sombir; Singh, Satinder Pal

2018-01-01

Space gaining is frequently required in orthodontics. Multiple loops were initially used for space gaining and alignment. The most common used mechanics for space gaining is the use of nickel-titanium open coil springs. The disadvantage of nickel-titanium coil spring is that they cannot be used until the arches are well aligned to receive the stiffer stainless steel wires. Therefore, a new method of gaining space during initial alignment and leveling has been developed and named as sleeve push technique (SPT). The nickel-titanium wires, i.e. 0.012 inches and 0.014 inches along with archwire sleeve (protective tubing) can be used in a modified way to gain space along with alignment. This method helps in gaining space right from day 1 of treatment. The archwire sleeve and nickel-titanium wire in this new SPT act as a mutually synergistic combination and provide the orthodontist with a completely new technique for space opening.

Sleeve push technique: A novel method of space gaining

Directory of Open Access Journals (Sweden)

Sanjeev Verma

2018-01-01

Full Text Available Space gaining is frequently required in orthodontics. Multiple loops were initially used for space gaining and alignment. The most common used mechanics for space gaining is the use of nickel–titanium open coil springs. The disadvantage of nickel–titanium coil spring is that they cannot be used until the arches are well aligned to receive the stiffer stainless steel wires. Therefore, a new method of gaining space during initial alignment and leveling has been developed and named as sleeve push technique (SPT. The nickel–titanium wires, i.e. 0.012 inches and 0.014 inches along with archwire sleeve (protective tubing can be used in a modified way to gain space along with alignment. This method helps in gaining space right from day 1 of treatment. The archwire sleeve and nickel–titanium wire in this new SPT act as a mutually synergistic combination and provide the orthodontist with a completely new technique for space opening.

Relative contributions of microbial and infrastructure heat at a crude oil-contaminated site

Science.gov (United States)

Warren, Ean; Bekins, Barbara A.

2018-04-01

Biodegradation of contaminants can increase the temperature in the subsurface due to heat generated from exothermic reactions, making temperature observations a potentially low-cost approach for determining microbial activity. For this technique to gain more widespread acceptance, it is necessary to better understand all the factors affecting the measured temperatures. Biodegradation has been occurring at a crude oil-contaminated site near Bemidji, Minnesota for 39 years, creating a quasi-steady-state plume of contaminants and degradation products. A model of subsurface heat generation and transport helps elucidate the contribution of microbial and infrastructure heating to observed temperature increases at this site. We created a steady-state, two-dimensional, heat transport model using previous-published parameter values for physical, chemical and biodegradation properties. Simulated temperature distributions closely match the observed average annual temperatures measured in the contaminated area at the site within less than 0.2 °C in the unsaturated zone and 0.4 °C in the saturated zone. The model results confirm that the observed subsurface heat from microbial activity is due primarily to methane oxidation in the unsaturated zone resulting in a 3.6 °C increase in average annual temperature. Another important source of subsurface heat is from the active, crude-oil pipelines crossing the site. The pipelines impact temperatures for a distance of 200 m and contribute half the heat. Model results show that not accounting for the heat from the pipelines leads to overestimating the degradation rates by a factor of 1.7, demonstrating the importance of identifying and quantifying all heat sources. The model results also highlighted a zone where previously unknown microbial activity is occurring at the site.

Heat transfer and critical heat flux in a spiral flow in an asymmetrical heated tube

International Nuclear Information System (INIS)

Boscary, J.; Association Euratom-CEA, Centre d'Etudes Nucleaires de Cadarache, 13 - Saint-Paul-lez-Durance

1997-03-01

The design of plasma facing components is crucial for plasma performance in next fusion reactors. These elements will be submitted to very high heat flux. They will be actively water-cooled by swirl tubes in the subcooled boiling regime. High heat flux experiments were conducted in order to analyse the heat transfer and to evaluate the critical heat flux. Water-cooled mock-ups were one-side heated by an electron beam gun for different thermal-hydraulic conditions. The critical heat flux was detected by an original method based on the isotherm modification on the heated surface. The wall heat transfer law including forced convection and subcooled boiling regimes was established. Numerical calculations of the material heat transfer conduction allowed the non-homogeneous distribution of the wall temperature and of the wall heat flux to be evaluated. The critical heat flux value was defined as the wall maximum heat flux. A critical heat flux model based on the liquid sublayer dryout under a vapor blanket was established. A good agreement with test results was found. (author)