Internal Energy Loss Research Articles

Hydraulic modelling of stratified bi-directional flow in a river mouth

Analytical results from internal hydraulic theory are presented for a horizontal channel connecting river- and sea-basin waters of slightly different densities. The maximal exchange of inviscid, two-layer flow is analysed for such a system, for the case of a non-rectangular channel. The internal hydraulic theory has been extended to include internal energy losses and related net barotropic flow components in the surface layer. The hydraulic model is tested using archival field measurements in the Pärnu River mouth, where stratified bi-directional flow, accompanied by variable sea-level conditions and river water discharges, was observed. The study demonstrates that internal hydraulic theory predicts satisfactorily the stratified bi-directional fluxes and density-interface depths observed in the river mouth. In this study the two-layer exchange problem is solved with two control points, but the theory can be applied quite generally to predict the layer depths of the river and marine waters in the estuarine interaction zone.

On the Influence of Transducer Internal Loss in Piezoelectric Energy Harvesting with SSHI Interface

In piezoelectric energy harvesting, the harvesting efficiency can be greatly improved with the switching interface called synchronized switch harvesting on inductor. However, we found from experiments that, the voltage across the piezoelectric element reverses a little bit after every inversion. This reversion, although small compared to the inversion, weakens the inversion effect produced by the switching inductive shortcut, and therefore decreases the voltage magnitude as well as the harvesting efficiency a lot. This phenomenon can also be found from the experimental waveforms in the previous studies; but it has never been pointed out. In these studies, the analytical results, which used the measured effective inversion factor in calculation, agreed with experiments; yet, the origin of the reversion after every switching action, as well as the quantitative relation between the ideal and effective inversion factors are of interest. In this article, the phenomenon on voltage reversion after every inversion is first described. Based on the experimental results, it is analyzed that this reversion is caused by the transducer internal loss. A revised model considering the influence of the internal energy loss is introduced. With this model, not only the reason, which causes the reversion after every inversion, can be explained; but also the quantitative relation between the ideal and effective inversion factors can be obtained. Experiments are also conducted to validate the revised model.

Study on optimal inertial-confinement-fusion hohlraum wall radial density and wall loss

Reducing hohlraum wall loss is one of the most important ways to improve hohlraum coupling efficiency in laser indirect drive inertial-confinement fusion. It is appeared that a high Z metallic foam as hohlraum wall material will reduce wall loss. By adjusting initial hohlraum wall density distribution along radial axes to ρ0(r)=kr, the numerical simulation results show that it can indeed bring best savings of ∼40% general wall loss. We conclude that absorbed energy mainly decreases by restraining rarefactions, and a proper slope k can optimize internal energy loss of low density and increased kinetic loss by subsonic. Also saved energy ratio reduces with source temperature decreasing. This approach would cut the reactor driver that needs quite substantially if experiments demonstrate it.

A General control mechanism of energy flow in the excited state of polyenic biochromophores

Quantum dynamics in photobiology is a highly controversial subject of modern research. In particular, the role of low-frequency vibrational coherence of biochromophores has been intensely discussed. Coherent control of polyenic chromophores, like carotenoids and retinoids, has been showing that the manipulation of such low frequency coherences may play a crucial role in the evolution of excited population and therefore in the efficiency of photosynthesis. However, no precise control mechanism has been derived. In order to clarify this open question, we combined quantum dynamical modelling with a sensitive experimental technique, namely Pump-Degenerate Four Wave Mixing (Pump-DFWM). In this work we investigate in detail the internal conversion channel of beta-carotene, an important polyenic chromophore, under multipulse excitation and focus on the role of the non-adiabatic coupling between excited-state potentials and the internal energy loss. Our control mechanism is based on the interference between wavepackets in the excited state, which leads to a transient evolution of the vibrational population dependent on the relative phase between excitation sub-pulses. Such a transient evolution can affect the branching ratio between competing channels in the excited state. Therefore, our results are able to rationalize pulse shapes found in a whole class of coherent control experiments involving polyenic biochromophores, like in light harvesting complexes and in bacteriorhodopsin.

New applications and performance of bioelectrochemical systems

Bioelectrochemical systems (BESs) are emerging technologies which use microorganisms to catalyze the reactions at the anode and/or cathode. BES research is advancing rapidly, and a whole range of applications using different electron donors and acceptors has already been developed. In this mini review, we focus on technological aspects of the expanding application of BESs. We will analyze the anode and cathode half-reactions in terms of their standard and actual potential and report the overpotentials of these half-reactions by comparing the reported potentials with their theoretical potentials. When combining anodes with cathodes in a BES, new bottlenecks and opportunities arise. For application of BESs, it is crucial to lower the internal energy losses and increase productivity at the same time. Membranes are a crucial element to obtain high efficiencies and pure products but increase the internal resistance of BESs. The comparison between production of fuels and chemicals in BESs and in present production processes should gain more attention in future BES research. By making this comparison, it will become clear if the scope of BESs can and should be further developed into the field of biorefineries.

A01 圧電アクチュエータとD級増幅器を用いた片持ち梁のエネルギー回生振動制御実験(OS5 スマート構造システム)

Energy consumption to drive actuator is thought as a disadvantage of active vibration control. However, the actuator of the active vibration control system absorbs energy from vibrating structure to suppress the vibration. In other words, the actuator regenerates energy from the vibrating structure. Especially, piezoelectric actuator can regenerate energy effectively, because it has few internal energy loss. Recently, class D amplifier based on switching circuit has been utilized due to its high-efficiency. It can drive the actuator with few energy loss and regenerate energy from the actuator. Therefore, the energy regenerative active vibration control system can be realized by using the class D amplifier to drive the piezoelectric actuator. The validity of the system has been shown by numerical simulation. In this paper, the power consumption of the proposing energy regenerative active vibration control system is measured by electrical power meter to show the validity of the system and the power consumption is compared with power consumption of conventional active vibration control system using linear amplifier. The result shows the power consumption of the proposing system is negative and the power consumption of the conventional system is positive. In other words, the proposing system is regenerating vibration energy in contrast with the conventional system is consuming energy from external source.

Performance estimation model of a torque converter part I: Correlation between the internal flow field and energy loss coefficient

The objective of this paper is to improve the performance estimation model of the internal flow field of a torque converter. Compared with performance experiment results, the converter based on the one-dimensional model does not satisfy the performance requirements demanded in practice. Therefore, we need to develop more predictable and reliable performance estimation models. In order to obtain shape information on three-dimensional blade geometry, a process of reverse engineering conducts a torque converter assembly, impeller, turbine and stator. In addition, a CFD simulation including mesh generation and post-processing was carried out to extract equivalent parameters from the internal flow field. The internal flow field can be explained by analyze the correlation between a performance estimation model and CFD analysis. The equivalent performance model adopts the variation of energy loss coefficients for a given operating condition according to the application of a changing energy loss coefficient by the least mean squares method. The estimated equivalent model improves the agreement in performance between experiments and the theoretical model. This model can reduce the error to within about 3 percent. Furthermore, this procedure for predicted performance achieves eminence in the estimation of the capacity factor.

Large eddy simulation of compressible channel flow

The present study is a contribution to the analysis of wall-bounded compressible flows, including a special focus on wall modeling for compressible turbulent boundary layer in a plane channel. large eddy simulation (LES) of fully developed isothermal channel flows at Re = 3,000 and Re = 4,880 with a sufficient mesh refinement at the wall are carried out in the Mach number range 0.3 ≤ M ≤ 3 for two different source term formulations: first the classical extension of the incompressible configuration by Coleman et al. (J. Fluid Mech. 305:159–183, 1995), second a formulation presently derived to model both streamwise pressure drop and streamwise internal energy loss in a spatially developed compressible channel flow. It is shown that the second formulation is consistent with the spatial problem and yields a much stronger cooling effect at the wall than the classical formulation. Based on the present LES data bank, compressibility and low Reynolds number effects are analysed in terms of coherent structure and statistics. A study of the universality of the structure of the turbulence in non-hypersonic compressible boundary layers (M≤5) is performed in reference to Bradshaw (Annu. Rev. Fluid. Mech. 9:33–54, 1977). An improvement of the van Driest transformation is proposed; it accounts for both density and viscosity changes in the wall layer. Consistently, a new integral wall scaling (yc+) which accounts for strong temperature gradients at the wall is developed for the present non-adiabatic compressible flow. The modification of the strong Reynolds analogy proposed by Huang et al. (J. Fluid Mech. 305:185–218, 1995) to model the correlation between velocity and temperature for non-adiabatic wall layers is assessed on the basis of a Crocco–Busemann relation specific to channel flow. The key role of the mixing turbulent Prandtl number Prm is pointed out. Results show very good agreement for both source formulations although each of them involve a very different amount of energy transfer at the wall.

Energy Regenerative Vibration Control of Smart Structure Using Class D Amplifier (1st Report, Numerical Study Using Equivalent Circuit Model and Circuit Simulator)

Active vibration control usually achieves higher performance compared to semi-active and passive vibration controls by consuming some amount of energy to drive actuator. However, the actuator of active control system absorbs energy from vibrating structure to suppress the vibration. In other words, the actuator regenerates energy from the vibrating structure. Especially, piezoelectric actuator often used in smart structures can regenerate energy effectively, because it has few internal energy loss. Energy consumption of active control is not caused by the actuator but caused by energy loss of conventional linear amplifier to drive the actuator. Recently, class D amplifier based on switching circuit has been utilized due to its high-efficiency. It can regenerate energy automatically from the load without loss under the ideal condition when the power consumption of the load is negative. Therefore, the energy regenerative active vibration control system can be realized by using the class D amplifier to drive the actuator. In this paper, we show the validity of the energy regenerative active vibration control of smart structure using the class D amplifier by numerical simulation of a smart cantilever beam with a piezoelectric actuator driven by a class D amplifier.

Enhanced surface hydrophobisation for improved performance of carbon aerogel electrochemical capacitor

Abstract A more efficient surfactant vinyltrimethoxysilane (vtmos) than previously reported one, sodium oleate (OAS), has been employed to enhance surface hydrophobisation of carbon aerogel for electric double layer capacitor (EDLC) application. In comparison with attachment of hydrophobic moiety of OAS species to carbon surface grafting of vinyltrimethoxysilane functional group enhances more efficiently the hydrophobisation of carbon material and the affinity toward propylene carbonate (PC) solvent, and accordingly improves more considerably the wettability of carbon in PC-based electrolyte solution. The enhanced wettability facilitates more rapid electrolyte ions transport within micropores of the vtmos modified carbon aerogel, resulting in lower internal resistance and energy loss than OAS modified carbon capacitor, and also favors more surface area for EDL formation, resulting in higher specific capacitance and energy for vtmos modified carbon aerogel electrochemical capacitor. In addition, vtmos modified carbon material has shown comparable charge–discharge cycling stability to that obtained by the original carbon.

Radiative transfer in cylindrical threads with incident radiation

Context. Relatively cool and dense structures embedded in the solar corona (filaments, prominences, spicules, etc.) may be observed in hydrogen lines. Sometimes they last during several solar rotations. Aims. Our goal is to evaluate the lifetime of cool structures of the solar corona, determine their evolution from given physical conditions, and compute models in thermal equilibrium. Methods. We use numerical methods to simultaneously solve the equations of NLTE radiative transfer, statistical equilibrium of hydrogen level populations, and electric neutrality. Radiative transfer equations are solved using cylindrical coordinates and prescribed solar incident radiations. The computation of internal energy and radiative losses and gains yields the rates of temperature evolution. Results. For isothermal-isobaric cylinders with prescribed physical conditions, we determine the lifetimes and evolution rates for different positions along the radius. For models with prescribed diameter and pressure, we determine the run of temperature vs. radius corresponding to thermal equilibrium. This equilibrium is found to be stable for the whole range of parameters under investigation. Conclusions. The cores of large and high-pressure cylinders are found to evolve very slowly. This opens the possibility of observing these cool structures at temperatures somewhat different from that corresponding to theoretical radiative equilibrium.

Flow Test: Particle-Level and Macroscale Analyses

This paper investigates the physical interpretation of the flow test. The research involves conducting image-monitored flow tests on mortars that are prepared with mixtures of natural round sand and crushed angular sand. The goal of the research is to evaluate both how the flow progresses and how the aggregate shape characteristics in cement affect mortar rheology. The research finds that within an energy-based framework, both the base shear at the mortar-plate interface and the loss of internal energy in the shear deformation are functions of the shear resistance within the mortar. As for particle shape, it is found that both packing density and the mobilized friction between aggregates affect it. The authors conclude that the amount of paste required to reduce grain interaction in order to attain adequate flow is defined by particle shape.

645 圧電アクチュエータによるエネルギー回生振動制御に関する研究

Energy consumption to drive actuator is thought as a disadvantage of active vibration control. However, the actuator of active vibration control system absorbs energy from vibrating structure to suppress the vibration. In other words, the actuator regenerates energy from the vibrating structure. Especially, piezoelectric actuator can regenerate energy effectively, because it has few internal energy loss. In this paper, energy consumption of SDOF model with piezoelectiric actuator and feedback control is investigated as an example and it is shown that energy consumption is not caused by the actuator but caused by energy loss of conventional linear amplifier to drive the actuator. Recently, class D amplifier based on switching circuit has been utilized due to its high-efficiency. It can drive the actuator with few energy loss. Therefore, the energy regenerative active vibration control system can be realized by using the class D amplifier to drive the actuator. The validity of the system is shown by numerical simulation.

2221 スマート構造のエネルギー回生振動制御に関する研究(スマート構造システム同定・振動制御・診断)

Energy consumption of actuator is thought as a disadvantage of active vibration control. However, the actuator of active vibration control system absorbs energy from vibrating structure to suppress the vibration. In other words, the actuator regenerates energy from the vibrating structure. Especially, piezoelectric actuator often used in smart structures can regenerate energy effectively, because it has few internal energy loss. Energy consumption of active control system is not caused by the actuator but caused by energy loss of conventional linear amplifier to drive the actuator. Recently, class D amplifier based on switching circuit has been utilized due to its high-efficiency. It can regenerate energy automatically from the load without loss under the ideal condition when the power consumption of the load is negative. Therefore, the energy regenerative active vibration control system can be realized by using the class D amplifier to drive the actuator. In this paper, we show the validity of the energy regenerative active vibration control of smart structure using the class D amplifier by numerical simulation of a smart cantilever beam with a piezoelectric actuator driven by a class D amplifier.

Electrical Properties of Niobium-Doped Titanium Dioxide. 1. Defect Disorder

The present work reports the electrical conductivity and thermoelectric power for Nb-doped TiO(2) at elevated temperatures (1073-1298 K) in the gas phase of controlled oxygen activity, 10(-14) Pa < p(O(2)) < 75 kPa. It is shown that in reduced conditions the Nb-doped TiO(2) exhibits metallic-type conductivity. This finding paves the way for the development of high-performance photoelectrodes with substantially reduced internal energy losses during charge transport. The present work also determined the equilibrium constant for the formation of oxygen vacancies and titanium vacancies for Nb-doped TiO(2).

Metallic TiO2

AbstractThe present work reports the discovery of the effect of metallic‐type conduction for Nb‐doped TiO2 (0.65 at% Nb). This effect was attested by measurements of electrical conductivity at elevated temperatures (973–1223 K) in the gas phase of controlled oxygen activities. It is shown that the temperature coefficient of the mobility of electrons in reduced conditions is negative. This finding paves the way for the development of high‐efficiency photoelectrodes for photoelectrochemical hydrogen generation from water using solar energy with substantially reduced internal energy losses for charge transport. (© 2006 WILEY‐VCH Verlag GmbH &amp; Co. KGaA, Weinheim)

Four laws of energy and momentum losses during capillary jet disintegration

Very simple and strict equations thoroughly characterizing the effect of capillary self-retardation of a droplet in the process of its detachment from the continuous part of a disintegrating jet, this effect having been revealed earlier and then confirmed experimentally, are derived from Newton’s laws of momentum and energy variations. Equations describe four total (over the time of disintegration) losses of the momentum, translational energy, total energy, and internal energy per unit mass of a liquid. As the rate of an initial cylindrical jet rises, the loss of momentum and internal energy unlimitedly decreases, the loss of translational energy limitedly rises, and the loss of total energy remains unchanged.

Estimation of State-of-Charge of Lead-Acid Batteries Using Electrochemistry Theorem

There are several methods to estimate the residual capacity of lead-acid batteries. Most of these methods are not able to precisely predict the amount of remaining capacity due to the battery aging effect. This paper presents a method using the electrochemistry theorem to analyze the electrode reaction resistance effect and to estimate the internal energy loss and the electrolyte specific gravity in batteries. Through a series of calculations, the state-of-charge of a lead-acid battery can be estimated. To validate the proposed algorithm, some experiments are conducted and the measured data is applied to the proposed method and two other methods for comparison. The experiment results prove that the proposed algorithm can accurately compute the state-of-charge of lead-acid batteries to a certain extend and can be used in real-time controls.

Battery testing by calculated discharge-curve method—Constant resistive load algorithm

Battery testing by calculated discharge-curve method (CDCM) includes battery, battery average cell and each of battery's cell 3D discharge curves. These discharge curves were generated by calculated discharge-curve algorithm (CDCA), using either high- or low-frequency monitored discharge data and are lying in battery/cell rectangular parallelepiped: open-circuit voltage–initial discharge current–time. CDCA defines the ordered six-tuple: time–current–voltage–capacity–energy on load–internal energy losses by which battery and battery's cells dynamic characteristics may be analyzed. Any of the six-tuple variables may be divided into the set of i = 1, …, n steps by constant step across the overall discharge interval and used as the domain of CDC algorithm procedure. CDCM, respectively, introduced average current and average voltage as the ratio of capacity to time and energy to capacity. Battery/cell rectangular parallelepiped: time–average current–average voltage is defined at any step of discharging. In this paper, the linear dependencies of average characteristics on the both power of battery/cell internal resistance and load intensity were presented and algebrically proofed. Battery's cells may be compared to battery average cell and may be classified by any characteristics. Discharge curves of alkaline-manganese MALLORY batteries, 9K62 (50 and 100 Ω), PX24 (100 and 166 Ω), PX21 (150 and 250 Ω) and 7K62 (100, 200 and 500 Ω) [T.R. Crompton, Small Batteries 2 (1982) 52] were used to demonstrate battery and battery average cell standard and CDC method characteristics. The mathematical calculations were conducting on IBM PC using Microsoft Excel software.

Computer simulations of the fission process of charged nanometre droplets

The process of fission of charged liquid droplets is an important stage of multiply charged ion formation in the electrospray ionization (ESI) process. ESI is currently the most powerful ionization method in the mass spectrometry of large molecules such as biopolymers. Fission plays a crucial role in the ion formation essentially in the range of nanosized droplets, since it determines the charge states of product ions. Usually the Rayleigh equation is used to determine critical conditions, at which the fission process takes place. This equation gives the value of the critical radius of the charged droplet as a function of its charge and specific surface energy. The Rayleigh equation does not give us the opportunity to determine charges and sizes of the fission fragments. In the present work we propose a mathematical model that describes the fission process of the charged liquid droplet in an external electrostatic field. The model is based on the quasi-equilibrium assumption that the most probable shape of the droplet corresponds to the minimum of the free energy of the system. The change in the internal kinetic energy and dissipative losses for the viscous liquid are also taken into account in the model.