Additional Energy Loss Research Articles

Drag induced radiative energy loss of semi-hard heavy quarks

We revisited gluon bremsstrahlung off a heavy quark in nuclear matter within higher twist formalism. In this work, we demonstrate that, in addition to transverse momentum diffusion parameter (qˆ), the gluon emission spectrum for a heavy quark is quite sensitive to eˆ, which quantify the amount of light-cone drag experienced by a parton. This effect leads to an additional energy loss term for heavy-quarks. From heavy flavor suppression data in ultra-relativistic heavy-ion collisions one can now estimate the value of this sub-leading non-perturbative jet transport parameter (eˆ) from our results.

Development of a virtual pump water flow meter using power derived from comprehensive energy loss analysis

Water flow rates are key controlled variables in chilled and hot water systems. The water flow rate through a pump can be virtually determined using a measured pump head and input power. Available input power can be either motor input power obtained from the connected variable-frequency drive or variable-frequency drive input power measured by a power meter. The harmonics created by the variable-frequency drive induce additional energy loss in the motor and consequently degrade the motor efficiency. The objective of this article is to evaluate a virtual pump water flow meter using either the variable-frequency drive input power or motor input power with calibrated pump, motor and variable-frequency drive efficiencies along with the consideration of additional harmonic energy loss. First, the water flow correlation with the measured pump head and available power input is discussed, then the calibration procedure is introduced to identify three efficiencies, and finally the experiment is conducted to develop and validate a virtual pump water flow meter on a pump motor variable-frequency drive system. The experimental results show that the water flow rates determined by the virtual water flow meter agrees well with the results measured by a physical water flow meter with the coefficient of determination of 0.91and 0.97, respectively.

Detuning and wave breaking during nonlinear surface wave focusing

Using an energy focusing technique, several transient wave trains were generated in a two-dimensional wave flume to investigate their nonlinear evolution. By increasing the initial wave steepness (S0), while all other parameters remained the same, non-breaking through breaking conditions were achieved. The experimental results demonstrated that the waves’ initial steepness affected the focusing process significantly. As expected, the nonlinear effects on wave packets with a low initial steepness were very small. However, for cases with large initial steepness, nonlinearity increased causing the wave packet to focus and break prematurely, a “detuning” process. As a result of the detuning process more than one breaker may occur, and more importantly when this ensues, energy loss was altered. It is found that for S0<0.274, only one breaker occurred, and the energy loss increased with increased initial steepness. For larger steepness, two breakers occurred and the total energy loss remained nearly constant (~17%) as the initial steepness was increased. As the initial steepness was increased still further, a large plunging breaking was obtained with additional energy loss (4%). These results suggest that the “detuning” has a pronounced influence not only on the resulting wave field, but on the resulting energy loss.

Sensitivity Analysis of a Transient-Based Frequency Domain Method for Extended Blockage Detection in Water Pipeline Systems

AbstractPartial blockages are commonly formed in water supply pipelines due to many factors, such as deposition, biofilm, and corrosion in the natural water supply process, as well as valve throttle in the artificial construction and operation process, which may cause additional energy losses and serious water supply accidents in the system. Recently, a transient-based frequency domain method (TBFDM) has been developed by the author for extended partial blockage detection, and it was found to be efficient, nonintrusive, and inexpensive to apply. While this method has been validated and applied for numerical and laboratory experiments in previous studies for a variety of blockage and hydraulic conditions, the application results revealed that the accuracy of the TBFDM may be easily affected by uncertainties in the experimental process. This paper investigates the sensitivity of the developed TBFDM to different uncertainty factors that commonly exist in water pipeline systems, with perspective to better und...

Additional energy loss in the series connection of supercapacitors

Additional energy loss in the series connection of supercapacitors

An Analysis of the Effect of Molten Salt Thermal Storage on Parabolic Trough Concentrated Solar Power Plant Efficiency

In the development of renewable energy sources, there has been a trend toward increasing and stabilising the power output of Concentrated Solar Power Plants (CSPPs) during times of reduced solar resource through the use of Thermal Energy Storage Devices (TESDs). This study investigates whether the use of a molten salt TESD decreases the efficiency of a parabolic trough CSPP due to additional system energy losses despite prolonging the operational time of the CSPP. A theoretical analysis of a simplified CSPP was made to determine if a TESD would impact the efficiency of the CSPP. This was followed up by a survey of currently active parabolic trough CSPPs both with and without molten salt TESDs. The theoretical analysis illustrated that a TESD would have no effect on the efficiency of a CSPP. However, the survey revealed that the use of a TESD improved the efficiency of a CSPP. The results of the study don't support the theoretical analysis or the hypothesis suggesting that a property has been overlooked. This property is most likely to be that generators tend to operate best within a certain temperature range, and in a CSPP the optimum temperature range cannot be maintained. This results in a generator being selected capable of operating for the longest period with the lowest amount of excess solar energy. When a TESD is implemented, the excess solar energy is stored for later use, prolonging the generator's running time and increasing the useable energy. The realisation of the ability of a TESD to increase the efficiency of a CSPP as well as extending its operating time shows a promising area of development in CSPP technology and increasing its application in electricity generation.

COMPONENTS OF THE TOTAL POWER LOSSES IN THREE-PHASE ENERGY SUPPLY SYSTEMS WITH SYMMETRIC SINUSOIDAL VOLTAGE SOURCE

Purpose. Three-phase energy supply system with a symmetrical resistive load operates in mode with the highest possible efficiency in a case of zero instantaneous reactive power and the absence of pulsations instantaneous active power. When load parameters are changed, three-phase energy supply system starts to operate in a mode with additional energy losses. The goal of the paper is to determinate the relations between the components of additional losses and their rezone. Methodology. We have applied the modern theory of instantaneous active and reactive power, the graphical filling complex branched energy supply system of simplified design scheme, the theory of electrical circuits, computer Matlab-simulation. Results. We have developed an universal relation to determine the components of total power loss in the three-phase supply systems with symmetrical three-phase sinusoidal voltage source and any possible load. Further verification of this relation in the Matlab-model of three-phase energy supply system shows its high accuracy. Originality. For the first time, we have carried out relation between RMS reactive and RMS active power instantaneous pulsation and the corresponding components of additional losses. Consequently it becomes possible to offer a unique method of weighting evaluation. Practical value. We have developed position for detecting the causes of additional losses in three-phase supply systems with symmetrical sinusoidal voltage source, as well as to substantiate the correctness of the choice of filter-compensating device. We have developed a Matlab-model which allows to investigate the energy efficiency of three-phase energy supply system and to calculate the components of additional power losses of any possible reasons for their occurrence.

Optical inverse-Compton emission from clusters of galaxies

Shocks around clusters of galaxies accelerate electrons which upscatter the Cosmic Microwave Background photons to higher-energies. We use an analytical model to calculate this inverse Compton (IC) emission, taking into account the effects of additional energy losses via synchrotron and Coulomb scattering. We find that the surface brightness of the optical IC emission increases with redshift and halo mass. The IC emission surface brightness, 32--34~mag~arcsec$^{-2}$, for massive clusters is potentially detectable by the newly developed Dragonfly Telephoto Array.

Guest Editorial

This is an IET Renewable Power Generation Special Section from the 3rd IET Renewable Power Generation Conference that was held in Naples. There was a wide range of topics among which were wind (turbines, offshore wind farms),photovoltaic generation, distribution power systems including power conversion, management of energy by means of demand side management and energy storage taking into consideration power markets. More than 120 papers were included in the conference's technical programme, and the topics covered a broad spectrum within the field of renewable power generation. A selection of papers presented at the Naples conference were considered appreciable by the Conference Session Chairs and invited to submit to the IET Renewable Power Generation journal. After extensive peer review, two significant papers were accepted for publication by the Editor-in-Chief and the Associate Editor. The accepted papers cover both generation by renewable sources and distribution of the energy treating, in particular, aspects related to the integration of renewable sources in the grid and the control and management of a distributed generation network. K. Musasa, M. N. Gitau and R. C. Bansal, in their paper “Dynamic analysis of DC-DC converter internal to an offshore wind farm”, have analysed the automatic generation control (AGC) problem and considered it in interconnected power systems with doubly-fed induction generator (DFIG)-based wind turbines. A non-linear least squares support vector machines (LS-SVM)-based AGC regulator is proposed; this is trained from an off-line data set obtained from designing and implementing the robust controller to power a system under diverse operating conditions and area load changes. An investigation of time response plots reveal that the designed LS-SVM-based AGC regulator shows promising performance for power systems with governor dead-band non-linearity when compared to that obtained with multi-layer perceptron neural networks and conventional PI-based AGC regulators for a wide range of parametric uncertainties and area load disturbances occurring in the area of the power system. In their paper, M. Cresta, F. M. Gatta, A. Geri, M. Maccioni, A. Mantineo and M. Paulucci analyse possible strategies for the control and management of an LV network with distributed generation connected at LV (consisting in photovoltaic power plants equipped with the last generation of inverters) and electric vehicles charging stations (EVCSs). Various possible scenarios have been studied: the LV network as actually operated; the network operated with the EVCS and the network operated with the EVCS and the NAS storage system. The evolution of voltage levels at the LV busbar, of power-factors at the secondary substation and of energy losses in the LV network have been calculated. By analysing the results, it was found that the installation of the EVCS itself does not present any criticality for the considered distribution network. A proposed optimal power flow detects optimal strategies for the management of reactive power flow supplied by the PV inverter and for the control of charge/discharge cycles of the NAS. From an economic point of view, the installation of the NAS appears to be unjustifiable because of both the high investment cost and the increase in operating costs (due to the additional energy losses). Lastly, the “demand response” practice, applied to “secondary substation” customers does not provide significant benefits on the network operation. However, this practice may generally constitute a convenient and effective solution for the implementation of the “load shifting” along a daily load diagram.

Surface waves on longitudinally bent and gradually curved boundaries of current-conducting media with a high conductivity, Zenneck wave

Quantitative estimates are obtained for the smallest values of the radii of curvature of longitudinal bends of the boundaries of highly conducting media and the largest transverse deviations of gradually curved (irregular) boundaries from the plane of the corresponding surface at which boundary surface waves propagate along the boundaries of such media without a substantial additional (to absorption in the medium) energy loss for radiation into space.

Additional Energy Losses from Asymmetric and Non-Sinusoidal Current in an Electrical Facility and Methods of their Reduction

Influence of the asymmetry and higher harmonics of current on the operation of an electrical facility is analyzed. The level of additional losses from the asymmetric and non-sinusoidal currents is evaluated for a 110 kV electrical network in the Siberian Region of the Russian Federation. Methods for reducing the additional energy losses in the electrical facility are suggested.

The Brickwork Joints Effect on the Thermotechnical Uniformity of the Exterior Walls from Gas-Concrete Blocks

In the article the brickwork joints effect on the thermotechnical uniformity parameters of the walls of gas-concrete blocks are considered. The additional thermal energy losses through joint masonry are calculated.The recommendations to reduce the brickwork joints effect on thermotechnical uniformity of external enclosure structures are offered.

Excitation of High-Q Whispering Gallery Modes in a Hemispherical Shielded Dielectric Cavity Using a Slot Transmission Line

We studied experimentally the electrodynamic characteristics of a hemispherical shielded dielectric cavity in the 8-mm wavelength range. The use of a slot transmission line is proposed to excite whispering gallery modes in such a cavity. It was found that the proposed excitation method is efficient and allows one to generate high-Q higher modes in a shielded dielectric cavity introducing no additional energy losses. It was shown experimentally that the achieved intrinsic Q-factor of the cavity under consideration can exceed the threshold values limited by the dissipative losses in its material. This effect is determined by the shift of the resonance field to the air gap between the metal and dielectric elements of the cavity. Agreement of the calculated and experimental data is demonstrated.

The H-mode density limit in the full tungsten ASDEX Upgrade tokamak

The high confinement mode (H-mode) is the operational scenario foreseen for ITER, DEMO and future fusion power plants. At high densities, which are favorable in order to maximize the fusion power, a back transition from the H-mode to the low confinement mode (L-mode) is observed. In present tokamaks, this H-mode density limit (HDL) occurs at densities on the order of, but below, the Greenwald density.In gas ramp discharges at the fully tungsten covered ASDEX Upgrade tokamak (AUG), four distinct operational phases are identified in the approach towards the HDL. These phases are a stable H-mode, a degrading H-mode, the breakdown of the H-mode and an L-mode. They are reproducible, quasi-stable plasma regimes and provide a framework in which the HDL can be further analyzed. During the evolution, energy losses are increased and a fueling limit is encountered. The latter is correlated to a plateau of electron density in the scrape-off layer (SOL). The well-known extension of the good confinement at high density with high triangularity is reflected in this scheme by extending the first phase to higher densities.In this work, two mechanisms are proposed, which can explain the experimental observations. The fueling limit is most likely correlated to an outward shift of the ionization profile. The additional energy loss channel is presumably linked to a regime of increased radial filament transport in the SOL. The SOL and divertor plasmas play a key role for both mechanisms, in line with the previous hypothesis that the HDL is edge-determined.The four phases are also observed in carbon covered AUG, although the HDL density exhibits a different dependency on the heating power and plasma current. This can be attributed to a changed energy loss channel in the presented scheme.

Implementation of higher order forced oscillations mode in shielded dielectric resonators by using slotline

The electromagnetic characteristics of the shielded hemisphere dielectric resonator in 8-mm waveband were investigated experimentally. The utilization of a slotline for the excitation of whispering gallery modes in such resonator was suggested. It has been defined that the suggested excitation technique is efficient. It provides an opportunity to excite the high Q-factor higher order modes in shielded dielectric resonator without additional energy losses. It has been proved experimentally that the unloaded Q factor achieved in the resonator under investigation may exceed the threshold values, which are limited by the dissipative losses in the dielectric resonator material, due to the shift of the resonance field in the air gap between the metal and the dielectric resonator elements. It was demonstrated that the symmetry breakdown of the investigated resonator leads to a significant deterioration of its electromagnetic characteristics.

Ab initio molecular dynamics calculations on scattering of hyperthermal H atoms from Cu(111) and Au(111).

Energy loss from the translational motion of an atom or molecule impinging on a metal surface to the surface may determine whether the incident particle can trap on the surface, and whether it has enough energy left to react with another molecule present at the surface. Although this is relevant to heterogeneous catalysis, the relative extent to which energy loss of hot atoms takes place to phonons or electron-hole pair (ehp) excitation, and its dependence on the system's parameters, remain largely unknown. We address these questions for two systems that present an extreme case of the mass ratio of the incident atom to the surface atom, i.e., H + Cu(111) and H + Au(111), by presenting adiabatic ab initio molecular dynamics (AIMD) predictions of the energy loss and angular distributions for an incidence energy of 5 eV. The results are compared to the results of AIMDEFp calculations modeling energy loss to ehp excitation using an electronic friction ("EF") model applied to the AIMD trajectories, so that the energy loss to the electrons is calculated "post" ("p") the computation of the AIMD trajectory. The AIMD calculations predict average energy losses of 0.38 eV for Cu(111) and 0.13-0.14 eV for Au(111) for H-atoms that scatter from these surfaces without penetrating the surface. These energies closely correspond with energy losses predicted with Baule models, which is suggestive of structure scattering. The predicted adiabatic integral energy loss spectra (integrated over all final scattering angles) all display a lowest energy peak at an energy corresponding to approximately 80% of the average adiabatic energy loss for non-penetrative scattering. In the adiabatic limit, this suggests a way of determining the approximate average energy loss of non-penetratively scattered H-atoms from the integral energy loss spectrum of all scattered H-atoms. The AIMDEFp calculations predict that in each case the lowest energy loss peak should show additional energy loss in the range 0.2-0.3 eV due to ehp excitation, which should be possible to observe. The average non-adiabatic energy losses for non-penetrative scattering exceed the adiabatic losses to phonons by 0.9-1.0 eV. This suggests that for scattering of hyperthermal H-atoms from coinage metals the dominant energy dissipation channel should be to ehp excitation. These predictions can be tested by experiments that combine techniques for generating H-atom beams that are well resolved in translational energy and for detecting the scattered atoms with high energy-resolution.

Kinetic energy redistribution on the hydrodynamic initial section

Scientific and technical information, regarding the issues of viscous and abnormally viscous liquid flow in geometrically heterogeneous channels is analyzed. The reasons of additional energy losses, caused by the occurrence of the inertial forces in the flow during the development of the velocity profile on the hydrodynamic initial section of channels are determined. Kinematic characteristics of unstabilized flow under various conditions of entry in the initial section are investigated. The analysis of kinetic energy redistribution in the flow is carried out. The functional dependence of the Coriolis coefficient on hydrodynamic conditions of entry in the initial section is found, and formulas to calculate its length are defined. An opportunity to identify additional pressure losses without using the hydrodynamic section method, associated with restructuring the velocity profile on its length is provided. Calculated dependences to compute the length of the flow stabilization section are defined. The obtained results of «control» over the hydrodynamic conditions of entry allow to create the optimal operating modes and improve performance characteristics of the process equipment.

Flume investigation of landslide debris–resisting baffles

Landslide debris is a common occurrence in mountainous regions around the world that can potentially result in disastrous consequences to downstream facilities. Flow-impeding structures are often constructed along the flow path to impede this hazardous phenomenon. Baffles are a type of flow-impeding structure regularly installed using empirical and prescriptive design methods as the interaction mechanism and the influence of baffle configuration on flow impedance is not well understood. A series of flume experiments were carried out to investigate flows characterizing landslide debris impacting an array of baffles using dry uniform sand. The influence of baffle height, row number, and spacing between successive rows was examined. Photoconductive sensors were used to estimate flow velocity, laser sensors were installed to measure flow depth profiles, and high-speed cameras were used to capture flow kinematics. Experimental results reveal that baffles can be categorized relative to the approach flow depth (h) and increasing the baffle height from 0.75h to 1.5h leads to a 40% increase in upstream flow depths from backwater effects, more effective development of subcritical conditions, and additional energy losses of up to 9%. Increasing the number of rows of 1.5h baffles from a single row to a three-row staggered array results in up to 72% additional energy loss. The energy loss is attributed to the deflection of granular jets and additional backwater effects. Increasing the row spacing from 50 to 100 mm results in up to a 14% increase in energy loss.

Characteristics of micro fine copper particles impact damping

Impact damping has been widely used in machine tools, robots, turbine machineries, aircrafts, and launch vehicles. Introducing micro fine particles into impact dampers may bring additional irreversible energy loss such as particle size reduction and plastic deformation for the damping, and carve out a new way to control the motion. For this purpose we use copper particles with an average size of 50 μm in ball impact dampers installed on a cantilever subjected to sinusoidal vibration within 96-hour impacting, and test the damping characteristics. We show that the response of the primary system can be divided into three stages, i.e., increasing, then deceasing, and increasing again. This dynamic feature reflects the deformation behaviors of the micro copper particles in different stages. In the first stage, the copper particles may display elastic behavior, and the sub-harmonic vibration of the steel ball may return part of the energy back to the primary system and enhance the response. In the second stage, the copper particle is forced into its yield point and the plastic deformation exhausts the energy and response of the system decline. In the third stage, hardening effect of the copper particles occurs and the response of system increases again. Our results may be significant to passively control the vibrations and material deformation.

Reducción de los Factores de Desbalance en un Sistema de Distribución de Media Tensión debido a la Inserción de Generación Distribuida

This paper presents a study and analysis of the importance and implications of the imbalance regulation, by the insertion of distributed generation, on a medium voltage electricity distribution network. The imbalance represents a problem of energy efficiency in electric power systems since it generate additional demands and energy losses For this study, and actual distribution system of the company EPEC in the province of Cordoba, Argentina, was considered. The modeling of the actual behavior by using the ATP/EMTP software. The results show that the effect of the distributed generation is positive in terms of reducing the imbalance in the network. The derating coefficient obtained is a good indicator of the energy performance. It is concluded that it is possible to regulate and reduce the imbalance with the inclusion of distributed generation.