Energy Loss Research Articles

Comparative analysis of reactive routing protocols for vehicular adhoc network communications

In the recent past, vehicular adhoc networks (VANETs) have gained a lot of importance. The routing protocols play a vital role to deliver payloads from one vehicle to another one while they are moving at relative speeds. It is a challenging task to select a routing protocol for VANETs because of the uneven distribution and high mobility of vehicles. In this paper, we have analysed the two standard reactive protocols, adhoc on-demand distance vector (AODV) and ant colony optimization (ACO). The performance comparison of AODV and ACO routing protocols has been presented in this paper. The results show AODV performed better in terms of energy consumption and routing overhead. While considering the throughput, energy loss ratio, and delay ACO has performed. ACO resulted as upperhand.

Collision characteristics of coal particles in arc-shaped plug elbow for pneumatic conveying

Particle collisions are one of the main causes of elbow wear. In this study, an arc-shaped plug elbow was proposed. Combined with the pneumatic conveying experiment of coal particles and the computational fluid dynamics and discrete element method (CFD–DEM) simulation of Euler–Lagrangian bilateral coupling, the variation rules of particle distribution, elbow wear, particle velocity, and collision energy loss were analyzed, the weakening characteristics of the arc-shaped plug on particle collision and elbow wear were revealed, and the criterion of the optimal structure was deduced. The results show that the arc angle is the main factor influencing particle collision and elbow wear in arc-shaped plugs, which determines the reasonable range of the dimensionless height. The average particle velocity of the arc-shaped plug elbow decreased rapidly during the plug-filling stage and was much lower than that of an ordinary elbow during the stable conveying stage. The growth rate of the collision energy loss tends to stabilize after stable particle accumulation. This is an important criterion for the optimal structure, in which the arc angle satisfies the condition that the plug completely contains the radiation area of the wear center, and the dimensionless height satisfies the condition that stable particle accumulation is formed in the plug.

Comparative study of passive magnetic bearing using four ring magnets: a critical review

Researchers on reducing energy losses caused by friction in small-scale wind turbines. This is crucial because a significant amount of energy is wasted due to friction in the main roller bearing. In order to overcome this, the concept of levitation has gained popularity. Levitation is achieved by employing the repelling forces between two opposing poles of a permanent magnet (PM), significantly reducing friction between the turbine stator and rotor. As a result, the overall energy production of the turbine increases. The use of passive permanent magnet bearings has several disadvantages, such as limited load-bearing capacity and rigidity. To address these limitations, we conducted numerical studies on four different configurations in order to enhance load-bearing capacity and stiffness. The results showed that the radial configuration outperformed the axial-type configuration in terms of stiffness and load-bearing capabilities in all four arrangements. Furthermore, it was revealed that radial passive magnetic bearings with adequate air gaps are not only more efficient but also less expensive than employing iron cores at the rear and between ring magnets for small-scale wind turbines.

Взаимосвязь окружной скорости и потерь энергии в проточной части центростремительной турбины с частичным облопачиванием рабочего колеса

Low-consumption turbomachines are devices that play an important role in the drive of various units in the field of shipbuilding, aircraft engineering and other branches of heavy engineering. They have some advantages over a high-average power turbine. The largest number of low-consumption turbomachines are made partial, i.e. with partial intake. The principle of a turbine with partial flapping of the impeller is considered as one of the types of partial turbomachines. The influence of the main velocity characteristic of the turbine stage on the loss of kinetic energy in the stage is investigated. The simulation of gas dynamic processes occurring in the turbine stage was carried out using the ANSYS Workbench software package. With the help of this complex, a three-dimensional geometric model of the turbine stage with varying degrees of impeller damping was created. By applying the finite element method, a computational grid, a computational model are generated, and boundary conditions of a numerical experiment are set. The result of the numerical experiment is graphs of the dependence of kinetic energy loss on the circumferential velocity (speed characteristics of the turbine stage). This dependence can be represented not only graphically, but also with the help of mathematical apparatus. An example of such an apparatus is the polynomial dependence. The considered mathematical design can be used in order to optimize mathematical models of gas flow in the flow part of a low-flow turbine. Cubic two-parameter polynomials of kinetic energy losses in the flow part of the nozzle and impeller are obtained, and an assessment of its applicability in the current mathematical model is given.

Deploying a Dipole Electric Field at the CsPbI3 Perovskite/Carbon Interface for Enhancing Hole Extraction and Photovoltaic Performance.

Carbon-based CsPbI3 perovskite solar cells without hole transporter (C-PSCs) have achieved intense attention due to its simple device structure and high chemical stability. However, the severe interface energy loss at the CsPbI3/carbon interface, attributed to the lower hole selectivity for inefficient charge separation, greatly limits device performance. Hence, dipole electric field (DEF) is deployed at the above interface to address the above issue by using a pole molecule, 4-trifluoromethyl-Phenylammonium iodide (CF3-PAI), in which the ─NH3 group anchors on the perovskite surface and the ─CF3 group extends away from it and connects with carbon electrode. The DEF is proven to align with the built-in electric field, that is pointing toward carbon electrode, which well enhances hole selectivity and charge separation at the interface. Besides, CF3-PAI molecules also serve as defect passivator for reducing trap state density, which further suppresses defect-induced non-radiative recombination. Consequently, the CsPbI3 C-PSCs achieve an excellent efficiency of 18.33% with a high VOC of 1.144V for inorganic C-PSCs without hole transporter.

Double Parton Scattering Versus Jet Quenching

A novel observable, the double nuclear modification factor, is proposed to probe simultaneously the initial and final state effects in nucleus-nucleus collisions. An interesting competition between the combinatorial enhancement in the double parton scattering and the suppression due to parton energy loss can be observed in the production rate of two hard particles. In particular, the production of J/ψ mesons in association with a W boson is not suppressed but is enhanced in the region of moderate transverse momenta, unlike the case of unassociated (inclusive) J/ψ production. At the same time, in the region of high enough transverse momenta the nuclear modification factor for associated J/ψ + W production converges to that of unassociated J/ψ.

Reduced-Dimensionality Al Nanocrystals: Nanowires, Nanobars, and Nanomoustaches.

Aluminum nanocrystals created by catalyst-driven colloidal synthesis support excellent plasmonic properties, due to their high level of elemental purity, monocrystallinity, and controlled size and shape. Reduction in the rate of nanocrystal growth enables the synthesis of highly anisotropic Al nanowires, nanobars, and singly twinned "nanomoustaches". Electron energy loss spectroscopy was used to study the plasmonic properties of these nanocrystals, spanning the broad energy range needed to map their plasmonic modes. The coupling between these nanocrystals and other plasmonic metal nanostructures, specifically Ag nanocubes and Au films of controlled nanoscale thickness, was investigated. Al nanocrystals show excellent long-term stability under atmospheric conditions, providing a practical alternative to coinage metal-based nanowires in assembled nanoscale devices.

Efficient Inverted CsPbI3 Solar Cells with Pb─S Contained Organosulfide‐Halide Perovskite Heterojunction

AbstractHere robust Pb‐S covalency is successfully incorporated into CsPbI3 heterojunction by introducing a new zwitterionic organosulfide‐halide perovskite on top of CsPbI3. Cysteamine (CYS: +NH3(CH2)2S−) will react with PbCl2 and form a new 3D perovskite with much shallower fermi level on CsPbI3 surface, constructing an efficient CsPbI3/[CYS][PbCl2] heterojunction. As a result, interfacial energy loss can be significantly inhibited and device open‐circuit voltage (Voc) is increased to over 1.20 V with champion efficiency of 20.38% in inverted CsPbI3 perovskite solar cells (PSCs). Besides, the intrinsic moisture and phase stability of [CYS][PbCl2] perovskite will effectively stabilize the CsPbI3 beneath owing to its robust Pb‐S covalency. PSCs with [CYS][PbCl2] exhibit significantly improved stability, whether in moist air or under continuous maximum power point (MPP) tracking.

Velocity Map Imaging Photoelectron Spectroscopy of Silver Iodide Aerosol Particles.

The valence band electronic structure of isolated silver iodide nanoparticles (AgI NP) was investigated by vacuum-ultraviolet aerosol photoelectron spectroscopy using the velocity map imaging technique (VUV VMI-PES). The VUV VMI-PES results were obtained for polydisperse aerosol produced by aggregation of hydrocolloid of silver iodide particles 8 - 15 nm in size. The ionization energy of the AgI particles was found to be 6.0 ± 0.1 eV with respect to the vacuum level. The DFT calculations showed that the main contribution to the density of AgI electronic states in the valence region originates from I 5p orbitals. The dependence of the asymmetry parameter on the electron energy showed that the value of the characteristic energy loss of excited photoelectrons was 2.7 eV, which coincided with the band gap of the nanomaterial.

Designing A-D-A Type Fused-Ring Electron Acceptors with a Bulky 3D Substituent at the Central Donor Core to Minimize Non-Radiative Losses and Enhance Organic Solar Cell Efficiency.

Designing and synthesizing narrow bandgap acceptors that exhibit high photoluminescence quantum yield (PLQY) and strong crystallinity is a highly effective, yet challenging, approach to reducing non-radiative energy losses (∆Enr) and boosting the performance of organic solar cells (OSCs). We have successfully designed and synthesized an A-D-A type fused-ring electron acceptor, named DM-F, which features a planar molecular backbone adorned with bulky three-dimensional camphane side groups at its central core. These bulky substituents effectively hinder the formation of H-aggregates of the acceptors, promoting the formation of more J-aggregates and notably elevating the PLQY of the acceptor in the film. As anticipated, DM-F showcases pronounced near-infrared absorption coupled with impressive crystallinity. Organic solar cells (OSCs) leveraging DM-F exhibit a high EQEEL value and remarkably low ∆Enr of 0.137 eV-currently the most minimal reported value for OSCs. Moreover, the power conversion efficiency (PCE) of binary and ternary OSCs utilizing DM-F has reached 16.16% and 20.09%, respectively, marking a new apex in reported efficiency within the OSCs field. In conclusion, our study reveals that designing narrow bandgap acceptors with high PLQY is an effective way to reduce ∆Enr and improve the PCE of OSCs.

Mott-Schottky Construction Boosted Plasmon Thermal and Electronic Effects on the Ag/CoV-LDH Nanohybrids for Highly-Efficient Water Oxidation.

Mott-Schottky construction and plasmon excitation represent two highly-efficient and closely-linked coping strategies to the high energy loss of oxygen evolution reaction (OER), but the combined effect has rarely been investigated. Herein, with Ag nanoparticles as electronic structure regulator and plasmon exciter, Ag/CoV-LDH@G nanohybrids (NHs) with Mott-Schottky heterojunction and notable plasmon effect are well-designed. Combining theoretical calculations with experiments, it is found that the Mott-Schottky construction modulates the Fermi level/energy band structure of CoV-LDH, which in turn leads to lowered d-band center (from -0.89 to -0.93), OER energy barrier (from 6.78 to 1.31eV), and preeminent plasmon thermal/electronic effects. The thermal effect can offset the endothermic enthalpy change of OER, promote the deprotonation of *OOH, and accelerate electron transfer kinetics. Whereas the electronic effect can increase the density of charge carriers (from 0.70×1020 to 1.64×1020 cm-3), lower the activation energy of OER (from 30.3 to 17.7kJ mol-1). Benefiting from these favorable factors, the Ag/CoV-LDH@G NHs show remarkable electrocatalytic performances, with an overpotential of 178 and 263mV to afford 10 and 100mA cm-2 for OER, respectively, and a low cell voltage of 1.42V to drive 10mA cm-2 for overall water splitting under near-infrared light irradiation.

Comparative study of combustion processes generated by the use of different fuels: energy and exergy analysis

Through energy and exergy analysis, the present work revisits the combustion processes generated using different fuels (CH4, C3H8, H2, LPG, Natural gas and Biogas) under the same operating conditions. First, numerical computations, in which the turbulent dynamic k-ϵ model coupled with a probability density function (PDF) approach together with different sub-models that ensure the reliability of the results, are used. Then, the First and Second Laws of thermodynamics are applied to all fuel combustion cases considered previously to predict the energy loss, exergy destruction and their corresponding efficiencies. Next, variations in the air factor, the air inlet temperature and the fuel inlet temperatures are considered to analyse the response of combustion system performance as well as energy and exergy losses for the different fuels under investigation. The results show an amelioration of combustion parameters for the mixture of fuel and air using values of λ greater than 1. Also, the preheating of the inlet air temperature has a positive effect on energetic parameters. However, preheating the inlet fuel does not take a considerable role in the efficiency amelioration and loss reduction of the combustion system. It further turns out that biogas features higher energy efficiency compared to other fuels, at approximately 89.64%, while hydrogen fuel exhibits higher exergy efficiency at around 78.70% followed by biogas with 74.96%.

Numerical investigation of flow characteristics in the front and rear chambers of centrifugal pump and pump as turbine

To investigate the flow characteristics in front chamber and rear chamber in pump mode and pump as turbine mode, a 3D computational model of a centrifugal pump was established, including the front and rear chamber. Based on Realizable k-ε turbulence model, numerical calculations of incompressible flow were carried out for internal viscous flow in two operating modes. Further analysis was conducted on the flow stability and hydraulic losses under two modes using energy gradient theory and entropy production theory. The numerical simulation results are within reasonable error compared to the experimental results in pump operation mode, which ensures the reliability of the numerical calculation method. The results indicate that the volumetric efficiency in both two modes is on an upward trend with increasing flow, but the volumetric efficiency of the pump mode is more significantly affected by changes in flow; the distribution patterns of dimensionless circumferential velocity and dimensionless radial velocity in the front and rear chambers under two operating modes are similar, but the distribution pattern of dimensionless radial velocity in the front chamber in turbine mode is significantly different from other operating conditions; flow instability is most likely to occur at the outlet of impeller, and the energy loss in clearance of wear-rings is greater than that in the pump chamber.

Concentrated Solar Power Techno-Economic Analysis in Humid Subtropical South America: The Uruguayan Case

Abstract This study assesses the feasibility of installing concentrated solar power plants in subtropical South America, particularly in Uruguay, by numerical simulations. Parabolic trough and solar power tower technologies are examined. A comprehensive literature analysis is conducted in order to evaluate initial investment, operation, and maintenance costs. Simulation models are validated in order to ensure results accuracy. The study is focused on the optimization of solar fields and storage sizes for five locations. The target set is to minimize the levelized cost of energy. In addition, energy losses and efficiencies are compared between parabolic trough and solar power tower technologies. Salto region in Uruguay is identified as the most suitable location for concentrated solar power projects. Optimized plants yield solar multiples of 3 or higher for solar power tower and around 4 for parabolic trough, with storage sizes ranging from 12 to 15 h, depending on the location. In Salto, the levelized cost of energy ranges from 148 to 175 USD/MW h for 110 MW solar power tower and from 169 to 220 USD/MW h for 55 MW parabolic trough plants, considering different investment cost scenarios. Levelized cost of energy is comparable for other locations, with a slight increase of approximately 10% for the least favorable location, Rocha. This work shows that while not yet competitive with photovoltaic or wind technologies, concentrated solar power plants show promise against fossil-fueled power plants and are expected to decrease further in cost.

Evaluating Outdoor Performance of PV Modules Using an Innovative Explicit One-Diode Model

Due to its simplicity, the one-diode model is commonly used for modeling the operation of photovoltaic (PV) modules at standard test conditions (STC). However, its inherent implicit nature often presents challenges in modeling PV energy production. In this paper, the innovative explicit one-diode model developed by us over time is adapted for estimating PV power production under real weather conditions. Simple yet accurate equations for calculating the energy output of a PV generator equipped with a maximum power point tracking (MPPT) system are proposed. The model’s performance is assessed under various normal and harsh operating conditions against measured data collected from the experimental setup located at the Solar Platform at West University of Timisoara, Romania. As an application of the new equation for maximum power, this paper presents a case study where the energy loss in the absence of an MPPT system is evaluated based on atmospheric and sky conditions.

Energy load analysis according to environmental control strategy of partially applied electrochromic smart window

ABSTRACT The percentage of energy consumed by buildings is very large in industry. Recently, the cases of applying smart technology to efficiently improve the energy waste of these buildings are increasing, and this study targets Electrochromic (EC) smart windows. Smart window means a window that can freely change Visible Light Transmittance (VLT) and Solar Heat Gain Coefficient (SHGC). Since windows are the largest medium that can cause energy loss in buildings, the application of smart windows enables efficient energy management. However, this technology currently has a high-cost problem, so a partial application to windows is proposed. This study aims to analyze the relationship between partially applied smart windows and energy loads. Smart windows require an environment control strategy because windows are primarily to provide a comfortable indoor environment. An environmental control strategy was established according to the application area of the smart window, and Useful Daylight Illuminance (UDI) was used. In addition, the energy load of the smart window in which the environmental control strategy was established was derived, and the relationship with the partially applied area was analyzed. This study provides information on how much the partial application of smart windows can save energy wastage in buildings.

Wakefield generation in hydrogen and lithium plasmas at FACET-II: Diagnostics and first beam-plasma interaction results

Plasma wakefield acceleration provides ultrahigh acceleration gradients of tens of GeV/m, providing a novel path toward efficient, compact, TeV-scale linear colliders, and high brightness free electron lasers. Critical to the success of these applications is demonstrating simultaneously high gradient acceleration, high energy transfer efficiency, and preservation of emittance, charge, and energy spread. Experiments at the FACET-II National User Facility at SLAC National Accelerator Laboratory aim to achieve all of these milestones in a single-stage plasma wakefield accelerator, providing a 10 GeV energy gain in a <1 m plasma with high energy transfer efficiency. Such a demonstration depends critically on diagnostics able to measure emittance with mm mrad accuracy, energy spectra to determine both percent level energy spread, and broadband energy gain and loss, incoming longitudinal phase space, and matching dynamics. This paper discusses the experimental setup at FACET-II, including the incoming beam parameters from the FACET-II linac, plasma sources, and diagnostics developed to meet this challenge. Initial progress on the generation of beam ionized wakes in meter-scale hydrogen gas is discussed as well as commissioning of the plasma sources and diagnostics. Published by the American Physical Society 2024

Comparative study of some rigorous and approximate methods for calculating the energy loss straggling

Some exact and approximate methods commonly used to calculate corrections to the Bethe stopping formula are modified and adapted by the authors to the calculation of the energy loss straggling (ELS). An intercomparison is carried out for results of approaches developed in the present work. An excellent agreement obtained between the results for ELS, calculated with an exact method previously proposed by one of the authors and the results of the Lindhard–Sørensen method for moderate relativistic energies. It is shown that some modified by authors approximate methods for the ELS calculating have the higher accuracy than the conventional approximate method of Lijian−Qing−Zhengming (LQZ). So, in all the cases considered, the accuracy of the twice modified LQZ method in the ELS calculations is higher than the accuracy of the usual LQZ method. The velocity averages of the relative error for Z = 92–118 of LQZ varies from 0.08% to 0.33%, and of LQZm2 – from 0.03% to 0.09%. A thrice modified LQZ method was also suggested in this work. The average error of LQZm3 becomes lower than the average error of LQZ, starting from Z = 99, and lower than the error of LQZm2, starting from Z = 109. A number of shortened LQZ methods for the ELS calculating have been proposed and developed too.

Energy- and Angle-Resolved Scattering of Ne from Dodecane Liquid Surfaces: Theory Corroborating Experiment.

Motivated by recent experimental work by the Neumark group, we present here an all-atom molecular dynamics study of Ne scattering from a dodecane liquid surface with the objective of elucidating the fundamental aspects of gas-liquid dynamics. Using a fine-tuned force field, the GPU-accelerated simulations reproduced semiquantitatively the energy- and angle-resolved experimental results. The branching ratio between the impulsive scattering (IS) and thermal desorption (TD) channels exhibits a clear correlation with the incidence energy (Ei) and angle. Ne atoms with lower Ei values are more likely to be trapped, yielding an increased TD ratio. For a given Ei, a large incidence angle led to a higher IS ratio. The energy transfer between Ne atoms and liquid dodecane was found to be more sensitive to the deflection angle than to the incidence or reflection angle. With an increasing deflection angle, the fractional energy loss increases, suggesting that more kinetic energy is transferred to the liquid.

Electric Vehicle Cluster Scheduling Model for Distribution Systems Considering Reactive-Power Compensation of Charging Piles

With the increasing number of electric vehicles (EVs), their uncoordinated charging poses a great challenge to the safe operation of the power grid. In addition, traditional individual-EV scheduling models may be difficult to solve due to the increasing number of constraints. Therefore, this paper proposes a cluster-based EV scheduling model. Firstly, electric vehicle clusters (EVCs) are formed based on the charging and discharging preferences of EV users and the expected time for EVs to leave. Secondly, the EVC energy and power boundary aggregation method based on the Minkowski addition algorithm is proposed. Finally, for the sake of reducing user charging cost and distribution network energy loss, and smoothing the daily load curve, an EVC scheduling model for EV participation in grid auxiliary services is proposed. The optimization model includes the reactive-power compensation of EV charging piles. The simulation results show that the proposed EVC scheduling model can greatly reduce the solution time compared to traditional individual-EV scheduling model. The model has high potential to be applied to large-scale EV scheduling. The reactive-power compensation provided by EV charging piles improves the voltage quality of the grid and enables more EVs to be connected to the grid.