Estimation Of Energy Losses Research Articles

Bioenergetics-Based Factorial Model to Determine Feed Requirement and Waste Output of Tilapia Produced under Commercial Conditions

A feed requirement and waste output model for commercial tilapia production was developed using the Fish-PrFEQ bioenergetics factorial approach and by an integration of data from commercial sources and the scientific literature. Different growth models were compared to determine the growth trajectory during three different production stages (nursery, 1–30g body weight (BW); pre-growout, 30–220g BW; and growout, >220g BW) based on data from a commercial tilapia farm in Ecuador. Feed requirement was estimated based on digestible energy requirement (DEreq), calculated from the expected energy gain (recovered energy, RE), and estimates of energy losses associated with basal metabolism (HeE), heat increment of feeding (HiE), and urinary and branchial excretion (UE+ZE), all estimated by compiling and analysing data from published studies. The waste outputs were estimated using a nutrient mass balance approach. Feed requirement model simulations were compared with the results from a growth trial carried out under controlled conditions.The modified TGC models produced a better fit of the growth trajectory of the fish on the commercial farm across production stages compared with other growth models (specific growth rate, linear model). Values predicted for body weight (r=0.998, P<0.001) and feed conversion (FCR, feed:gain) (r=0.849, P<0.01) by the models were highly correlated to the observations from the growth trial. Total solid wastes (TSW) output of tilapia fed according to a realistic production scenario (feeds with 40, 30, 28% CP for nursery, pre-growout and grow out stages, respectively) was estimated at about 331 and 423kg per tonne of feed fed and per tonne of fish produced, respectively. These results show that this model could be a valuable tool for production and feeding management on commercial tilapia culture operations.

Influence of aerosols pollution on the amount of collectable solar energy

The paper is focused on the estimation of collectable solar energy losses in aerosol pollution events. To do this, a parametric clear sky solar irradiance model has been built and validated. For applying the model, a set of four meteorological parameters (ozone, nitrogen dioxide, water vapor column content and the Ångström turbidity coefficient) are required at input. The energy loss in a pollution episode was evaluated as the difference between the clear sky solar irradiation computed in two situations: (1) Using measured values for all inputs and (2) using measured values for all inputs excepting the Ångström turbidity coefficient, for which a climatological reference value has been assumed. The calculations show that the aerosol pollution can lead to a significant loss of collectable solar energy, of over 20%. Overall results drive to the generic conclusion that the pollution episodes should be considered in both stages of a photovoltaic plant: in development, by taking them into account when the typical meteorological year is constructed, and in the exploiting stage, by accounting them in the forecasting procedure of the output power. The study was conducted with data collected in Timisoara, Romania, during 2011 and 2012.

The neutrino energy loss by electron capture of nuclides 55Co and 56Ni in explosive stellar environments

Using the Shell-Model Monte Carlo method and the Random Phase Approximation theory, we carry out an estimation of neutrino energy loss (NEL) for 55Co and 56Ni by electron capture. We find that the NEL rates increase greatly at some typical stellar conditions, and can even exceed five orders of magnitude (e.g. T9 = 38.5, Ye = 0.42 for 56Ni). On the other hand, the error factor C shows that the fit is fairly good for two results at higher density and lower temperature, and the maximum error is ∼ 1.2%. However, the maximum error is ∼ 55.60% (e.g. T9 = 18.5, Ye = 0.45) at lower density and higher temperature.

Tire Energy Loss Estimation Method to Predict. Tire Influences on Fuel Consumption of Mode Driving

Tire Energy Loss Estimation Method to Predict. Tire Influences on Fuel Consumption of Mode Driving

Multiobjective optimal design of runner blade using efficiency and draft tube pulsation criteria

In the present work new criteria of optimal design method for turbine runner [1] are proposed. Firstly, based on the efficient method which couples direct simulation of 3D turbulent flow and engineering semi empirical formulas, the combined method is built for hydraulic energy losses estimation in the whole turbine water passage and the efficiency criterion is formulated. Secondly, the criterion of dynamic loads minimization is developed for those caused by vortex rope precession downstream of the runner. This criterion is based on the finding that the monotonic increase of meridional velocity component in the direction to runner hub, downstream of its blades, provides for decreasing the intensity of vortex rope and thereafter, minimization of pressure pulsation amplitude. The developed algorithm was applied to optimal design of 640 MW Francis turbine runner. It can ensure high efficiency at best efficiency operating point as well as diminished pressure pulsations at full load regime.

Energy Losses Estimation in Power Distribution Systems

Estimating technical losses is fundamental to the planning and economics of electric power networks. This paper surveys the evolution of the ideas behind energy loss estimation and focuses on the development of the concepts of the loss factor and equivalent hours. The paper next identifies difficulties in using maximum demands and the loss factor to estimate energy losses. Based on this analysis, this study proposes an alternative loss estimation approach that relies on the “loss coefficient” as the fundamental parameter for describing load variations in loss estimation. A large load-curve data bank from Brazilian utilities is used to characterize load-curve parameters and provide perspective on the old and new concepts. Practical applications put the proposed ideas into perspective, showing how the use of average demands and loss coefficient can help to make better cable choices, increase accuracy in loss estimation for distribution transformers, and enhance the quality of information in loss estimation analysis.

The role of bottom friction in models of nonbreaking tsunami wave runup on the shore

The role of bottom friction in the runup of nonbreaking long waves on the shore is analyzed. The case of the normal incidence of monochromatic waves is considered. The relief of the model region consists of an even horizontal bottom area conjugated with a flat slope. The energy dissipation is estimated as the work of bottom friction forces over the wave field obtained using the known analytical solution based on the Carrier-Greenspan transforms. Estimates of energy losses for waves whose periods are typical for tsunami waves have been obtained. The energy dissipation is shown to be not concentrated in the shore line area as a rule. The question about the practicability of using partially reflecting boundary conditions on the coast to take into account the bottom friction in large-scale models of tsunami propagation is considered.

열역학적 방법을 사용한 펌프 효율 측정에 관한 연구

Carbon emission generated by energy issues is one of the major problems which all countries concern. The International Energy Agency recommends to improve 15-30[%] of energy efficiency than now. Government has pushed the domestic energy saving policies and incentives and penalties were also given in that direction. Pumps are widely used to transfer fluids and they consume at least 20[%] power of each nation. Their loss of energy is huge if they have been operated at low efficiency for long time. Low efficiency of these pumps is often due to incorrect design or degradation. Pump efficiency can be measured to estimate energy loss. If it is low, the pump may be repaired or replaced with new one. This paper introduces thermodynamic method to measure pump efficiency using only two kinds of sensors for temperature and pressure. It can calculate best efficiency point(BEP) of actual systems easily and fast. Its values were compared with the real performance curve provided by pump maker and we got almost similar performance curves from the repeated experiment.

Modified stochastic estimation of load dependent energy losses in electric distribution networks

This paper proposes a new modified stochastic model of steady-state operating conditions for a load-dependent (current-dependent) energy losses estimation in electric distribution networks of any configuration. This model is based on stochastic simulation of a power covariance matrix and electric power loads. Electric power load variation is presented in the form of a linear combination of some independent random factors. It is able to correctly take into account a variety of power system operating conditions with a small volume of initial information, and to determine energy losses for a certain time-period in one computation of expected values of power loads. Energy losses are determined with sufficient accuracy and reliability for practical purposes.

A comprehensive method for estimating energy losses due to shading of GC-BIPV systems using monitoring data

In this paper, a comprehensive method for evaluating energy losses of a grid-connected building integrated photovoltaic (GC-BIPV) system due to partial shading is described. The method consists to make a comparison between theoretical and measured (monitoring data) curves of the maximum output energy produced by a GC-BIPV system installed at Jaén University (Spain). The results showed that loss of energy is 1.79kWh/day, which corresponds to a shading factor of 14.4%.

Estimated energy intake and energy loss among low‐income formula‐fed infants: Mid‐point analysis of Phase 1 of the “Baby‐Mine” study

Phase 1 of the Baby‐Mine study focuses on how infant‐feeding practices impact rate of weight gain among 2‐to 4‐month‐old formula‐feeding infants. Low‐income mothers of healthy, term infants &lt; 3 mo of age, who report using reconstituted infant formula, were recruited via fliers distributed to the local health department, pregnancy resource centers, social media websites, and a birth registry. At ~ 2 and ~ 4 months of age, infant intake (and estimated spit‐up) was recorded for 48 hrs, and infant weight and length measured. Mid‐point evaluation was performed using data from the 31 mothers completing both data collection points. Of the 31 infants, 18 were male and 13 female and average birth weight was 3229.3g. At time point 1 (TP 1), infants were, on average, 2.3 months old, weighed 5603g, offered 4.8 oz of formula (consuming 4.3 oz), consumed 624 kcal/d, lost an estimated 8.1 kcal/d via spit‐up, and 29% were offered cereal in the bottle at least once. At time point 2 (TP 2), infants were, on average, 4.1 months old, weighed 7039g, were offered 5.8 oz of formula (consuming 5.1 oz), consumed 700 kcal/d, lost an estimated 8.3 kcal/d via spit‐up, and 54.8% were offered cereal in the bottle at least once. Rate of daily gain, from TP 1 to TP2, was 27.4g, which is higher than the recommended daily gain. Estimated energy loss and inappropriate rate of weight gain are likely to be important targets for nutrition education among new parents. Funds: USDA/NIFA/AFRI Award‐2010‐85215‐20663.

Use of Balance Methods for Assessment of Short‐Term Changes in Body Composition

Balance methods reveal changes in body energy, nitrogen, macro- and micronutrients as well as fluid in response to different feeding regimens. Under metabolic ward conditions, where physical activity is restricted and activity and food intake are controlled, the errors of estimates of energy intake, energy expenditure, and energy losses are about 2, 4, and 2%, respectively. Balance techniques can be used to validate techniques of in vivo body composition analysis (BCA). This is necessary since immediate and transient changes in body composition in response to a change in diet adversely affect the validity of techniques by violating the assumptions underlying standard methods (i.e., a constant composition or hydration of lean mass). Using two compartment reference methods, like densitometry, dual X-ray absorptiometry (DXA) or deuterium dilution, changes in fat mass with caloric restriction and overfeeding can be measured with a minimal detectable change (MDC) of 1.0-2.0kg. However, when compared against balance data, the validity of these techniques to measure short-term changes in body composition is poor. The noninvasive and rapid new quantitative magnetic resonance (QMR) technique has a high precision with a MDC of 0.18kg of fat mass. The validity of QMR to assess short-term changes in fat mass is challenged by comparison to balance data. Today, techniques used for in vivo BCA should be related to steady state conditions only, while in the nonsteady state, the use of balance methods is recommended to assess short-term changes in body composition.

Estimation of approximate activation energy loss and mass transfer coefficient from a polarization curve of a polymer electrolyte fuel cell

A simple electrochemical approach is presented to quantitatively predict activation energy and mass transfer coefficient from a polarization curve of polymer electrolyte fuel cells to examine the membrane-electrode assembly (MEA) performance. It is assumed that the initial voltage drop at open circuit voltage is due to kinetic activation energy and that the current loss at short circuit current is due to mass transfer resistance. Accordingly, voltage drop in the activation polarization is converted into a change in the Gibbs free energy to determine the activation energy requirement. The mass transfer coefficient for current losses is derived from Fick’s law, based on the mass transfer limitation of oxygen at the oxygen reduction reaction sites. Case studies from the literature show reasonable correlations to the operating conditions, thereby providing a useful tool for prediction of the preliminary values of the activation energy and mass transfer coefficient for an MEA under various conditions.

The Cascade of Tidal Energy from Low to High Modes on a Continental Slope

Abstract The linear transfer of tidal energy from large to small scales is quantified for small tidal excursion over a near-critical continental slope. A theoretical framework for low-wavenumber energy transfer is derived from “flat bottom” vertical modes and evaluated with observations from the Oregon continental slope. To better understand the observations, local tidal dynamics are modeled with a superposition of two idealized numerical simulations, one forced by local surface-tide velocities and the other by an obliquely incident internal tide generated at the Mendocino Escarpment 315 km southwest of the study site. The simulations reproduce many aspects of the observed internal tide and verify the modal-energy balances. Observed transfer of tidal energy into high-mode internal tides is quantitatively consistent with observed turbulent kinetic energy (TKE) dissipation. Locally generated and incident simulated internal tides are superposed with varying phase shifts to mimic the effects of the temporally varying mesoscale. Altering the phase of the incident internal tide alters (i) internal-tide energy flux, (ii) internal-tide generation, and (iii) energy conversion to high modes, suggesting that tidally driven TKE dissipation may vary between 0 and 500 watts per meter of coastline on 3–5-day time scales. Comparison of observed in situ internal-tide generation and satellite-derived estimates of surface-tide energy loss is inconclusive.

Experimental investigation of turbulent flow in a channel with the backward-facing inclined step

The work deals with the experimental investigation of turbulent flow in a closed channel with the backward-facing inclined step. Experiments were carried by means of the PIV optical measuring method in the channel of the rectangular cross-section in the inlet part and with inclined steps of the constant height H mm and various inclination angles for a wide range of the Reynolds number. The attention was paid especially to the separation region behind the step and to the relaxation of the shear layer after the reattachment in the outlet part of the channel. The dependence of the length of the separation region on the Reynolds number was obtained for various step angles. Optical measurements were completed by the measurement of static pressure distribution in the inlet and outlet part of the channel to estimate energy losses.

Influence of glazing size on energy efficiency of timber-frame buildings

Competitive fields of residential building are aware that today’s prefabricated timber building is extremely highly valuated and is capable of fulfilling all of the demands from our society and from the environment that we live in. Additionally, due to strict energy requirements, the tendency to use a higher share of glass wall surfaces occurs worldwide. Therefore, the aim of this research is to investigate an alternative solution by using a glass sheathing material instead of classical wood-based or fibre-plaster sheathing boards in timber-framed walls as the main load-bearing elements in prefabricated timber-framed buildings with a special focus on the annual energy demand behaviour for heating and cooling. The research is based on a case study of a two-storey house with a prefabricated timber-frame structural system and its parametric analysis of an increased-proportion-of-the-glazing-surfaces impact, taking the climate data for Ljubljana into consideration. The analysis was carried out on different exterior timber-frame wall elements having different thermal properties, while the rest of the parameters, such as the ground plan of the model as well as the active systems, roof and floor slab assemblies remain constant. The graphical presentation includes a function curve showing the annual energy demand for heating and cooling depending on the proportion of the glazing area in relation to the total surface area of the south-oriented façade. The comparative analysis results can nevertheless serve as a good frame of reference to civil engineers and architects in an approximate estimation of energy losses accompanying the different positioning and proportion of glazing surfaces while using various prefabricated timber-frame wall elements as well as serving some basic principles in the energy refurbishment of old timber-frame buildings.

Computer Modelling of Hybrid Solar Parabolic Trough Concentrator Systems—Electrical Part

This paper is to develop a mathematical model for hybrid solar parabolic trough concentrator (PTC) systems. The model is for estimation of energy outputs, losses and efficiencies of various parts of the system which operates under different climate condition, diverse configurations and a range of loading conditions. Automated system optimization can be quickly obtained by trying numerous different system configurations. In hybrid PTC system, photovoltaic cells are also installed on the receiver pipes. Solar energy is directly converted to electricity by photovoltaic cells. The working fluid circulating in the receiver pipes is for solar thermal purpose as well as to cool down the temperature of solar cells. The overall yield of the system is increased and therefore capital cost is reduced. A detailed analytical model simulating a hybrid PTC system has been developed by modelling and integrating sub-components into one model and a simulation software has been developed. The software is a valuable design tools for engineers whenever they are designing hybrid PTC systems, which are likely feasible in application to densely populated city with sub-tropical climatic conditions in southern part of China. System performance has been tested with a set of initial parameters and preliminary results have been produced.

Evaluation of Energy Loss and Charge Sharing in Cadmium Telluride Detectors for Photon-Counting Computed Tomography

We present estimates of energy loss and charge sharing for a pixelated cadmium telluride (CdTe) detector used for photon-counting spectral computed tomography (CT). In a photon-counting pixelated CdTe detector, several physical effects lead to detected events with reduced energies, including Compton scattering, fluorescence emission, charge diffusion, trapping of charge carriers and slow-hole-motion-induced incomplete charge collection. Charge sharing is the result of the lost energy being collected by adjacent pixels. We simulated the photon transport and the charge-collection process with a Monte Carlo-based simulation and evaluated these effects on the detector performance. The trapping effect and poor hole collection have been studied together using an analytical model. We also investigated the detector response under the influence of only the fluorescence effect. We conclude that the charge sharing effects should be taken into account when the pixel is smaller than 1 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> . A straightforward way to decrease the double counting of X-rays from events with charge sharing is to increase the electronic threshold. However, increasing the threshold comes at the cost of losing low-energy events, which is undesirable, at least in applications such as pediatric imaging.

CMS tracking performance results from early LHC operation

The first LHC pp collisions at centre-of-mass energies of 0.9 and 2.36 TeV were recorded by the CMS detector in December 2009. The trajectories of charged particles produced in the collisions were reconstructed using the all-silicon Tracker and their momenta were measured in the 3.8 T axial magnetic field. Results from the Tracker commissioning are presented including studies of timing, efficiency, signal-to-noise, resolution, and ionization energy. Reconstructed tracks are used to benchmark the performance in terms of track and vertex resolutions, reconstruction of decays, estimation of ionization energy loss, as well as identification of photon conversions, nuclear interactions, and heavy-flavour decays.

Estimation of Energy Loss in Conveyor Systems due to Idler Indentation

This paper applies viscoelasticity and Winkler foundation assumptions to the analysis of the energy loss in conveyor systems caused by idler-indentation into the rubber cover of the belt. The analysis yields a simple algebraic model that relates the indentation energy loss to various critical parameters of a conveyor system. Such properties include rubber viscoelastic properties characterized by G′ and G′′, transportation rate, speed, idler spacing, and belt width. Analysis shows that this model is more accurate and more informative than other prevailing models. This model will be useful for the design and optimization of energy consumption in conveyor systems.