Irreversible Energy Loss Research Articles

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.

Size Dependent Transitions in Nanoscale Dissipation

The irreversible loss of energy that occurs when a nanoscale tip vibrates over a surface can be monitored and quantified in amplitude modulation atomic force microscopy (AM AFM). Furthermore, two distinct dissipative processes can be identified and related to viscous and hysteretic forces respectively. Here, experimental evidence of a transition from viscous to hysteretic prevalent dissipation during mechanical contact is provided as the size of the tip increases from a few nm to 10 nm or more. Long range dissipation, defined as distances for which mechanical contact does not occur, is also investigated and related to capillary interactions. Experiments conducted on freshly cleaved mica samples show that energy dissipation increases with tip size and relative humidity in the long-range before mechanical contact occurs. Long- and short-range interactions are discussed in terms of observables both experimentally and by numerically integrating the equation of motion.

The Schrödinger equation with friction from the quantum trajectory perspective

Similarity of equations of motion for the classical and quantum trajectories is used to introduce a friction term dependent on the wavefunction phase into the time-dependent Schrödinger equation. The term describes irreversible energy loss by the quantum system. The force of friction is proportional to the velocity of a quantum trajectory. The resulting Schrödinger equation is nonlinear, conserves wavefunction normalization, and evolves an arbitrary wavefunction into the ground state of the system (of appropriate symmetry if applicable). Decrease in energy is proportional to the average kinetic energy of the quantum trajectory ensemble. Dynamics in the high friction regime is suitable for simple models of reactions proceeding with energy transfer from the system to the environment. Examples of dynamics are given for single and symmetric and asymmetric double well potentials.

Electrocatalytic Formation and Inactivation of Intermetallic Compounds in Electrorefining of Silicon

Silicon for solar cell purposes is today produced by an energy intensive process exhibiting high irreversible thermodynamic energy losses. The purity of the product; 99,9999999 pct (9N), far exceeds what is generally accepted to be the requirements for photovoltaic purposes (4-6N). According to thermodynamics, all elements except boron may be removed from silicon by three layer electrochemical refining above the melting point of Si. Boron, on the other hand, shows higher affinity to specific transition metals compared to silicon. This may be exploited by applying two principles in parallel; electrochemical refining and electrocatalyzed reaction-precipitation of transition metal borides as heavy, stable particles. In this study we report on the formation of such compounds at the cathode-electrolyte interface during electrochemical refining. The trends and mechanisms observed in the laboratory scale investigation indicate that high purity silicon may be produced in industrial scale reactors at low cost- and energy intensity.

Hysteresis of the martensitic phase transition in magnetocaloric-effect Ni-Mn-Sn alloys

We have investigated the hysteresis of the temperature- and magnetic field--induced martensitic phase transition in ${\text{Ni}}_{50.4}{\text{Mn}}_{34.0}{\text{Sn}}_{15.6}$. Specifically, we have characterized the fraction of martensite and cubic Heusler phase present along a variety of temperature and magnetic field paths using magnetization as a proxy for the fraction of phases present. We present these results and discuss (1) the thermodynamics of the thermal- and magnetic field--induced hysteresis and (2) the impact of this hysteresis on the magnetocaloric effect of the alloy. We demonstrate that both temperature and magnetic field are equivalent driving forces for the phase transition and result in equivalent hysteresis behavior linked through the magnetic Gibbs free energy. The hysteresis reduces the useful magnetocaloric effect of the alloy by allowing only a limited fraction of the alloy to transform cyclicly between the martensite and the austenite phase under application and removal of magnetic fields up to 9 T, and by dissipating work through irreversible energy loss. While the importance of a large thermodynamically reversible magnetic entropy change is generally accepted, our results suggest that the hysteresis behavior is equally critical in evaluating the effective magnetocaloric effect of a material.

A concept of a spacecraft with small initial mass placed in the near-earth orbit by a laser rocket engine

A method and results of calculating the laser radiation power values necessary to place an artificial earth satellite in orbit are presented; the values depend on the initial vehicle mass, velocity of the working fluid efflux from the laser rocket engine nozzle, velocity of vehicle motion, optimal values of thrust-to-weight ratio taking into account irreversible energy losses in the rocket engine jet. The possibility of creating a spacecraft with small initial mass is substantiated. A layout scheme of the propulsive system is proposed that makes it possible to divide total laser radiation power and to use atmospheric air as a working fluid.

An anelastic spectroscopy, differential scanning calorimetry and X-ray diffraction study of the crystallization process of Mg–Ni–Fe alloys

The effects of heating-induced crystallization on the structural and mechanical properties of Mg–Ni–Fe amorphous ribbons were studied by anelastic spectroscopy, differential scanning calorimetry (DSC) and X-ray diffraction. DSC results show that the crystallization occurs through several non-reversible steps, which correspond to significant changes in the Young’s modulus and concomitant irreversible elastic energy loss peaks. Moreover, an anelastic peak is found at 215 K, which for the first time indicates the presence of some dynamical process related to the simultaneous presence of different phases. The formation of a metastable Mg6Ni phase is detected, which transforms into Mg and Mg2Ni stable phases. A quantitative analysis of the different phases present at the different steps was also carried out. © 2007 Elsevier B.V. All rights reserved.

Volumetric methods for evaluating energy loss and heat transfer in cavity flows

AbstractMethods have been developed for calculating irreversible energy losses and rates of heat transfer from computational fluid dynamics solutions using volume integrations of energy dissipation or entropy production functions. These methods contrast with the more usual approach of performing first law energy balances over the boundaries of a flow domain. Advantages of the volumetric approach are that the estimates involve the whole flow domain and are hence based on more information than would otherwise be used, and that the energy dissipation or entropy production functions allow for detailed assessment of the mechanisms and regions of energy loss or entropy production.Volume integrations are applied to the calculation of viscous losses in a lid‐driven cavity flow, and to the viscous losses and heat transfer due to natural convection in a side‐heated cavity. In the convection problem comparison with the entropy increase across a stationary heat conducting layer leads to a novel volume integral expression for the Nusselt number. The predictions using this method compare well with traditional surface integrals and benchmark results. Copyright © 2007 John Wiley & Sons, Ltd.

Volumetric methods for evaluating irreversible energy losses and entropy production with application to bioengineering flows

AbstractMethods for calculating irreversible energy losses and rates of heat transfer from computational fluid dynamics solutions using volume integrations of energy dissipation functions contrast with the more usual approach of performing first law energy balances over the boundaries of a flow domain. Advantages of the approach are that the estimates involve the whole flow domain, and are hence based on more information than would otherwise be used, and that the energy dissipation function allows for detailed assessment of the mechanisms and regions of energy loss.The research was motivated by a need to clarify energy losses by haemodynamics in the greater vessels of the human body, in particular, the Fontan connection. For this application irreversible energy losses were calculated using the viscous dissipation function. Streamwise integration of the viscous dissipation function is also used to explore the ways in which different flow structures contribute to energy losses. Copyright © 2006 John Wiley & Sons, Ltd.

On the Nature of Angular Momentum Transport in Nonradiative Accretion Flows

The principles underlying a proposed class of black hole accretion models are examined. The flows are generally referred to as and are characterized by inward transport of angular momentum by thermal convection and outward viscous transport, vanishing mass accretion, and vanishing local energy dissipation. In this paper, we examine the viability of these ideas by explicitly calculating the leading-order angular momentum transport of axisymmetric modes in magnetized, differentially rotating, stratified flows. The modes are destabilized by the generalized magnetorotational instability, including the effects of angular velocity and entropy gradients. It is explicitly shown that modes that would be stable in the absence of a destabilizing entropy gradient transport angular momentum outward. There are no inward-transporting modes at all, unless the magnitude of the (imaginary) Brunt-Vaisala frequency is comparable to the epicyclic frequency, a condition requiring substantial levels of dissipation. When inward-transporting modes do exist, they appear at long wavelengths, unencumbered by magnetic tension. Moreover, very general thermodynamic principles prohibit the complete recovery of irreversible dissipative energy losses, a central feature of convection-dominated models. Dissipationless flow is incompatible with the increasing inward entropy gradient needed for the existence of inward-transporting modes. Indeed, under steady conditions, dissipation of the free energy of differential rotation inevitably requires outward angular momentum transport. Our results are in good agreement with global MHD simulations, which find significant levels of outward transport and energy dissipation, whether or not destabilizing entropy gradients are present.

The quantum-jump approach to dissipative dynamics in quantum optics

Dissipation, the irreversible loss of energy and coherence, from a microsystem is the result of coupling to a much larger macrosystem (or reservoir) that is so large that one has no chance of keeping track of all of its degrees of freedom. The microsystem evolution is then described by tracing over the reservoir states, which results in an irreversible decay as excitation leaks out of the initially excited microsystems into the outer reservoir environment. Earlier treatments of this dissipation used density matrices to describe an ensemble of microsystems, either in the Schr\"odinger picture with master equations, or in the Heisenberg picture with Langevin equations. The development of experimental techniques to study single quantum systems (for example, single trapped ions, or cavity-radiation-field modes) has stimulated the construction of theoretical methods to describe individual realizations conditioned on a particular observation record of the decay channel. These methods, variously described as quantum-jump, Monte Carlo wave function, and quantum-trajectory methods, are the subject of this review article. We discuss their derivation, apply them to a number of current problems in quantum optics, and relate them to ensemble descriptions.

Effect of Irreversible Energy Loss on the Fracture Toughness and the Work-of-Fracture of Ceramics Toughened by Crack Face Bridging

The relationship between the fracture toughness and the work-of-fracture of ceramics toughened by crack bridging was discussed using a constant crack closure stress model including irreversible energy loss in the bridging region during crack propagation. The Irwin similarity relationship could not be applied to the bridged crack without modifying stress intensity factor and energy release rate considering the crack closure stress and the energy loss. Moreover, the fracture toughness was not simply related with the work-of-fracture even if the modified Irwin similarity was applied. The fracture toughness was determined as a function of the crack closure stress and the length of the bridging region regardless of the energy loss. On the other hand, the work-of-fracture of bridged crack was increased by the irreversible energy consumption as well as crack closure stress.

Scintillating shallow-water waveguides

An analysis of acoustic wave propagation in a random shallow-water waveguide with an energy absorbing sub-bottom is presented, in which deviations of the index of refraction are a stochastic process. The specific model studied is motivated by the oceanic waveguide in shallow waters, in which the sub-bottom sediment leads to energy loss from the acoustic field, and the stochastic process results from internal (i.e., density) waves. In terms of the normal modes of the waveguide, the randomness leads to mode coupling while the energy loss results from different attenuation rates for the various modes (i.e., mode stripping). The distinction in shallow water is that there exists a competition between the mode-coupling terms, which redistribute the modal energies, and mode stripping, which results in an irreversible loss of energy. Theoretically, averaged equations are formulated for both the modal intensities and fluctuations (the second and fourth moments of acoustic pressure, respectively), similar to previous formulations which, however, did not include the effects of sub-bottom absorption of acoustic energy. The theory developed here predicts that there is a mismatch between decay rates between the second and fourth moments, implying that the scintillation index (which is a measure of the strength of the random scattering) grows exponentially in range. Thus the usual concept of equilibrium or saturated statistics must be modified. This theoretical prediction is generally valid and depends only on assuming the forward scattering approximation, the Markov approximation (i.e., the short-range nature of the correlations between sound-speed fluctuations) and neglecting the cross-modal coherences. In order to assess the importance of these assumptions Monte Carlo simulations of stochastic coupled-mode equations are presented. For these simulations, models of internal-wave processes, deterministic shallow-water acoustic environments, and sub-bottom attenuation that simplify the numerical computation were chosen. While these models are unrealistic they illustrate the theoretically predicted behavior.

Cyclic fatigue in monolithic alumina: mechanisms for crack advance promoted by frictional wear of grain bridges

The microstructural basis of cyclic fatigue-crack propagation in monolithic alumina has been investigated experimentally and theoretically. A true cyclic fatigue effect has been verified, distinct from environmentally assisted slow crack growth (static fatigue). Microstructures with smaller grain sizes were found to promote faster crack-growth rates; growth rates were also increased at higher load ratios (i.e. ratio of minimum to maximum applied loads). Using in situ crack-path analysis performed on a tensile loading stage mounted in the scanning electron microscope, grain bridging was observed to be the primary source of toughening by crack-tip shielding. In fact, crack advance under cyclic fatigue appeared to result from a decrease in the shielding capacity of these bridges commensurate with oscillatory loading. It is proposed that the primary source of this degradation is frictional wear at the boundaries of the bridging grains, consistent with recently proposed bridging/degradation models, and as seen via fractographic and in situ analyses; specifically, load versus crack-openingdisplacement hysteresis loops can be measured and related to the irreversible energy losses corresponding to this phenomenon.

Thermodynamic analysis of the martensitic transformation in NiTi—I. Effect of heat treatment on transformation behaviour

The effect of heat treatment on the martensitic transformation behaviour of NiTi has been investigated. Transformation temperature measurements are interpreted in terms of the chemical, elastic and irreversible components of the overall transformation free energy change. It is shown that the occurrence of a two-stage parent-R-martensite transformation on cooling and a single-stage reverse transformation in specimens annealed at intermediate temperatures is a consequence of the irreversible energy loss associated with the martensitic transformation. The increase in the R transformation temperature in specimens heat treated at low temperature is shown to result from changes to the reversible, elastic or chemical, components of the transformation free energy change.

Acoustic wave propagation in a random, shallow water waveguide

An analysis of acoustic wave propagation in a random shallow water waveguide is presented, in which deviations of the index of refraction are a stochastic process. The specific model studied is motivated by the oceanic waveguide in shallow waters, in which the subbottom sediment leads to energy loss from the acoustic field, and the stochastic process results from internal (i.e., density) waves. In terms of the normal modes of the waveguide, the randomness leads to mode coupling while the energy loss results from different attenuation rates for the various modes (i.e., mode stripping). Monte Carlo simulations of stochastic coupled-mode equations are presented [similar to L. B. Dozier and F. D. Tappert, J. Acoust. Soc. Am. 63, 353–364 (1978)], from which the average modal intensity (second moments of the field) and the scintillation index for this model are derived. It is shown that the usual concept of equilibrium or saturated statistics must be modified. In the context of an unrealistically simplified model with only two modes, an interpretion is provided whereby this result is due to the competition between the mode coupling terms, which redistribute the modal energies, and mode stripping, which results in an irreversible loss of energy.

Modeling Pipe Networks Dominated by Junctions

The transfer of energy and irreversible energy losses at junctions may dominate flow distribution in pipe networks comprised of connected large‐diameter pipes of short lengths. Neglecting the junction effects when calculating network hydraulics is unacceptable and the use of constant loss coefficients to represent these effects in such networks may not be adequate. In the present study, precise relationships based on experimental data are used to represent the junction‐loss coefficients. These relations, which depend on flow conditions, are incorporated into a computer network analysis model. Significant deviations in flow rates calculated using constant junction loss coefficients and the semiempirical relationships based on experimental data are obtained using an example network characterized by short pipe sections. It is also shown that although there is always a net energy loss at a junction, there may be significant exchange of specific energy from one flow stream to the other. The use of constant loss coefficients is inadequate to account for this phenomenon.

Ion Beam Cooling by Radiation and Electron Heat Sink

The concept for transverse temperature reduction of an arbitrary species intense ion beam is investigated. In this concept a transversally hot ion beam of arbitrary species is brought into thermal contact with a cooler electron beam with a much higher line density moving at the same speed. Thermal equilibrium is established through Coulomb interaction, with the electrons acting as heat sink. The transversally cool electron beam is either initially available or obtainable by its interaction with the comoving ions through an irreversible radiative energy loss process.

Irreversible energy losses of flow through porous and perforated plates

For a realistic numerical simulation of a hypothetical core disruptive accident (HCDA) it is often important to take into account perforated plates. Inclusion of the plates drastically changes the loading pattern of the containment and a significant amount of the fluid's energy is dissipated as it passes through the plates. At present the PISCES-2DELK program simulates the perforated plates explicitly by defining the geometric boundary and the fluid passages. This boundary is attached to a movable structure, thereby ensuring the correct fluid-structure interaction. Equally important as the correct fluid-structure interaction is the energy dissipation, associated with fluid flow through the narrow passages. This aspect will be treated in this paper. Simple PISCES-2DELK calculations will illustrate that the fluid undergoes an internal energy rise, well beyond the reversible component (d e = − pd v). The excess energy can be marked as heating of the fluid and is therefore irreversible. Furthermore, as the flow through the narrow passages tends to a “stationary state”, an a posteriori computed energy loss factor C D levels off to a value which corresponds to those common in the literature. The method of explicitly defining the geometric boundaries of perforated/porous structures is advantageous, for the following reasons: (a) it takes into account volume occupying effects of the perforated/porous plates; (b) it is equally applicable for the dynamic and for the more or less stationary state; and (c) it simulates the fluid-structure interaction and energy dissipation of the fluid, without any a priori assumptions about energy loss factors.

A Statistical Evaluation of Methods Used To Predict Pressure Losses for Multiphase Flow in Vertical Oilwell Tubing

Several methods for predicting pressure losses for upward, concurrent, continuous, multiphase flow in vertical oilwell tubing were tested against measured pressure losses from 726 well tests. This comparison of well known pressure-loss correlations reveals the relative strengths and weaknesses of each correlation and should be useful in selecting satisfactory methods for various applications. Introduction Several correlations have been published that can be used to predict pressure losses in vertical oilwell tubing for the simultaneous, upward, concurrent, continuous flow of oil, water, and gas. Because of the extreme complexity of multiphase flow, the proposed correlations are by necessity highly empirical. The validity of the correlations is then somewhat limited to the quality and scope of the data upon which they are based. Therefore, some correlations perform quite well for cases in the range of the data used in developing the correlation but fail for other applications.The purpose of this study is to ascertain the accuracy of several pressure-loss prediction methods in terms of flow variables familiar to the practicing engineer. The results of the study should assist the petroleum production engineer in selecting the most petroleum production engineer in selecting the most accurate method for his problem and also should indicate the general accuracy to be expected from the methods.The correlations included in the study are those of Poettmann and Carpenter, Baxendell and Thomas, Poettmann and Carpenter, Baxendell and Thomas, Duns and Ros, Fancher and Brown, Hagedorn and Brown, and Orkiszewski. Each of these correlations was proposed specifically for predicting pressure losses in vertical oilwell tubing for the upward flow of multi-phase well fluids.The pressure-loss prediction methods were programmed for the IBM 360 computer and tested programmed for the IBM 360 computer and tested against 726 well tests from field and experimental wells. A statistical analysis was made to find the most acceptable method for different ranges of flow variables and also the method having the best over-all performance for predicting the measured pressure performance for predicting the measured pressure losses. Pressure-Loss Prediction Correlations Pressure-Loss Prediction Correlations The six correlations chosen for study will be discussed briefly. A review of the history and content of multi-phase flow literature and a more detailed discussion of individual correlations may be found in Brown.The correlation of Poettmann and Carpenter is a relatively simple and practical one to predict pressure losses in flowing wells. However, its very pressure losses in flowing wells. However, its very simplicity limits its accuracy. The method was included in this study for comparison, and because it served as a starting point for later correlations.Poettmann and Carpenter correlated the irreversible energy losses of 49 well tests with a Fanning-type friction term. The friction term was related to the numerator of the Reynolds number for the well fluid mixture. No attempt was made to account for liquid holdup (volume fraction liquid in a pipe section), but rather an average density of produced fluids corrected for down-hole conditions was used. The correlation reproduced the measured pressure gradients to an average deviation of 1.8 percent and a standard deviation from the average of 8.3 percent. JPT P. 903