Energy Damping Research Articles

Theoretical and experimental analyses of acoustic characteristics of fine-grain powder considering longitudinal vibration and boundary layer viscosity

There was a previous study to derive the sound absorption coefficient of the powder layers comprising powder particles with a diameter of a few tens of μm. According to this previous method, the impact of air viscosity at the boundary layer generated in the pores between the powder particles is neglected. Therefore, precision is not guaranteed when the particle diameter is relatively large or when the density is relatively high. In the present study, to obtain the sound absorption coefficient of the powder layer more accurately, in addition to the above-described longitudinal vibration mode, the energy damping property of the boundary layer viscosity was calculated using the transfer-matrix method. As a result, when the longitudinal vibration mode and boundary layer viscosity were considered, the theoretical value tended to be closer to the experimental value than when only the longitudinal vibration was considered.

Earthquake-induced energy response of reinforced concrete dual-system tall buildings

The distribution of earthquake-induced energy in a 42-storey reinforced concrete dual-system building at three ground shaking intensities was investigated. The earthquake-induced energy response of the building was obtained in terms of elastic energy (kinetic energy and strain energy) and inelastic energy (hysteretic energy and structural damping energy) components for each structural member. Hysteretic energy is an indicator of inelastic deformations (i.e. potential damage) and is considered particularly important as it leads to high irrecoverable energy demands in a building and identifies critical members that require higher energy absorption capacity. The ratio of hysteretic energy to input energy was assessed among different structural members as well as along the building height. The results showed that the hysteretic energy constituted less than 10% of the total input energy and was mostly dissipated in the frame members for low-intensity events, whereas 75% of the input energy was dissipated in the hysteretic mechanism, prominently by the beams. In terms of hysteretic energy demands, the critical floor levels were found to be the 12th and 26th floors. The findings of this research will help engineers obtain a reasonable estimate of the expected hysteretic energy demand once the input energy is known.

New way to dampen the energy of medium- and high-pressure flows

The current practice of hydraulic engineering construction applies four methods for damping extra energy of excess water discharge: throwing out the stream into the tailwater; using twisting of the stream in the water passageway, in a water-well, and on a multistage drop; and energy damping in a vertical shaft. The cheapest method is energy damping by throwing the jet into the downstream reservoir. The main disadvantages limiting the use of this method include the need for appropriate topographic conditions in the tailrace basin, strong rocks in the river channel, and the possibility of water throwing at a large distance from the hydropower project, which restricts the use of this method. Extra energy damping with the use of twisting flow in the water passageway requires complex structures, providing for a rotational movement of water and forming a deep vacuum in the outlet conduit. The breaking of vacuum requires a large amount of air, which causes dynamic modes, and its removal complicates the design of energy damping structures. The most reliable way of energy damping is damping in a stilling well. But the disadvantages of water-sucking wells are low efficiency accompanied by an uneven distribution of specific discharges in the inlet section and a sharp increase in the cost at high-pressure hydroelectric installations. The use of multistage cross-fall drastically facilitates the operation of a stilling well and serves as its supplement. Energy damping in a vertical shaft is easy to use. Still, it results in trapping a large amount of air at all operating modes, which has limited its practical use in hydraulic engineering construction. However, the damping of flow energy in a vertical shaft except for possible air supply has shown high efficiency of operation in combination with a diversion water pipe with a reverse slope. A variant of such design of flow energy damping in a vacuum vertical shaft has been developed and studied as applied to conditions of the Rogun hydropower project. Model studies of the design on the scale of 1:100 showed high efficiency and reliability in all possible ranges of discharged flow rates.

Experimental study of horizontal effects of flow on non-erosion absorbers in the presence of cavitation

This article is devoted to one relatively small issue of the dynamics of hydraulic structures, the determination of horizontal hydrodynamic loads on energy absorbers of a high-pressure catchment area in a cavitating flow in the presence of erosion-free absorbers. In connection with the intensive construction of high and medium-pressure hydroelectric systems, spillways that operate at high flow rates, a very urgent task is to develop reliable and economical downstream devices that provide intensive damping of flow energy in a stilling well with favorable uninterrupted flow regimes and the absence of cavitation erosion of streamlined elements. Traditional methods of extinguishing energy using stilling wells and walls do not always solve the problem. In several cases, additional elements such as energy absorbers are installed, which effectively deal with malfunctioning currents. However, most of the used types of absorbers have a serious drawback - they are destroyed during cavitation studies by prof. N.P. Rozanov and his students made it possible, based on experiments, to develop several types of erosion-free or close to erosion-free dampers and obtain a dependence to determine the hydrodynamic loads acting on them at various stages of cavitation. This made it possible to use energy absorbers at high flow rates, which was done at the spillways of the Shamkhor and Artyomovsk hydroelectric power plants.

Pneumatic Breakwaters and Their Use for Ships protection in Coastal and Offshore Areas of Persian Gulf

Pneumatic breakwater is a kind of wave energy damping structure which is capable of reducing a portion of wave energy. The structure utilizes an air bubble column deep in water to induce a counter flow which opposes the wave current resulting in damping of its energy and the height of the wave. Fast installation with the least space occupied along with posing no obstacle for shipping and maneuvering are advantages of this structures. Although the disadvantage of this method can be wasting of almost half the energy of outgoing air. Using this method, a range of waves with lower height can be achieved. To draw the most advantage out of this method, the pneumatic breakwater can be combined with Floating breakwater. In order to explore the effectiveness of Hybrid breakwater, a physical or numerical model in deeper water depth is required. Utilizing this method in coasts where other kind of ordinary breakwaters are not practical and temporarily in the vicinity of shore in deeper water is economically effective. This breakwater can be attached to the ship (DAHET) or rig (ATAB). Hybrid system creates a safe atmosphere for smooth transfer of the passengers of crew boats to and from wharf in a continuous manner even in rough sea and bad weather condition. Case study in Persian Gulf indicates that pneumatic breakwater is practical in Persian Gulf except for longitude between 51° and 57° and latitude between 24° and 28° Northern which extends from eastern north to 14 Kilometers of Parsian Coasts and 30 Kilometers of Lengeh Port and from western south to 6 Kilometers of Dubai coasts to Abuzabi and from eastern north to 12 km of Kargan port to Sirik and from western south to 130 Kilometers of eastern coasts of Qatar.

Cyclic Performance of End-Plate Biaxial Moment Connection with HSS Columns

This paper presents a numerical study on the seismic performance of end-plate moment connection between I-beam to HSS (hollow structural section) column stiffened by outer diaphragms (EP-HSS). In previous experimental research, this moment connection showed a satisfactory performance according to requirements established in Seismic provisions. However, one type of joint was studied and bidirectional and axial loads were not considered. In this since, several configurations representative of 2D interior joints and 3D interior and exterior joints in a steel building were modeled and subjected to unidirectional or bidirectional cyclic displacements according to protocol in seismic provisions. Firstly, a similar joint configuration was calibrated from experimental data, obtaining an acceptable adjustment. The assessment of seismic performance was based on hysteretic curves, failure mechanisms, stiffness, dissipated energy, and equivalent damping. The results obtained showed a ductile failure modes for 2D and 3D joint configurations with EP-HSS moment connection. The axial load has no significant effect on the moment connection. However, it affects the column strength due to the increase of the stresses in the column wall. Compared with 2D joints, 3D joints reached higher deformations even when a similar number of beams is used. The external diaphragms to the column panel zone provided rigidity in the joints and no degradation of slope for each loop in load/reload segment for elastic loop; therefore, curves without pinching were observed. All inelastic deformation is concentrated mainly in the beams. A moment resistance above 80% of the capacity of the beam at a drift of 4% is achieved in all joints. From the results reached, the use of EP-HSS moment connection with hollow structural section columns is a reliable alternative in seismic zones when steel moment frames are employed.

Вплив повздовжньо-динамічних навантажень на міцність гальмової важільної передачі візка вагона, обладнаного новим концептом упряжного пристрою

Досліджено повздовжню навантаженість вантажного поїзда, обладнаного новими концептами упряжного пристрою. Встановлено, що використання концепту упряжного пристрою дозволяє знизити повздовжню навантаженість поїзда майже на 30% у порівнянні з типовою схемою взаємодії локомотива з вагонами. Проведено розрахунок на міцність гальмової важільної передачі вантажного вагона, обладнаного новим концептом упряжного пристрою. При цьому максимальні еквівалентні напруження в елементах гальмової важільної передачі нижчі майже на 35% у порівнянні з типовою схемою Проведені дослідження сприятимуть створенню інноваційних конструкцій рухомого складу з покращеними техніко-економічними та динамічними показниками.

Polistiren Kaplı Küresel Şekilli Alüminyum Köpüklerin Ezilme Davranışlarının Araştırılması

In this study, the crushing behavior of spherically shaped aluminum foam pieces coated with polystyrene and uncoated under compression load was investigated. The spherical shaped aluminum foam parts produced by powder metallurgy with diameters of 8 mm and 10 mm were coated with polystyrene by the injection molding process. The obtained foam elements were then subject to quasi-static compression tests at room temperature with a constant cross head speed of 1 mm/min. According to the experimental results, polystyrene coatings increased the energy damping capacity of the foams by approximately 115% while increasing the density by about 50%.

Assessment of Cyclic Load Induced Energy Dissipation and Damping on GFRP Composite Laminate

Polymeric composites exhibit load sensitive stiffness unlike the case of homogeneous metallic material. Composites are widely used in dynamic loading environment and hence it is necessary to study their response in terms of structural properties. Behavioural changes of glass epoxy composite laminate on exposure to cyclic loading has been assessed in terms of energy dissipation (Ed) and Damping factor (DF) by hysteresis loop. GFRP composite specimens (UD-0, 0/30/60/0, 0/45/0/-45, 0/90/90/0, and 0/90/0/90) are exposed to low velocity constant amplitude cyclic loading using a laboratory arrangement (by an eccentric disc) at 4.6 Hz and 8.6 Hz frequencies. In fibre-reinforced composites apart from the fibre volume fraction, the fibre interaction angle significantly influences their dynamic properties on loading. Unidirectional (UD-0) laminate exhibits low damping/energy dissipation, while 0/90/0/90 laminate with large fibre interaction angle shows highest damping/energy dissipation. Whereas, symmetric cross ply (0/90/90/0) laminate acts as a performance demarcation among the chosen laminates. Thus, optimum Ed/DF properties of GFRP laminate in dynamic environment is attributed to symmetric lay-up, smaller fibre orientation interaction angle in the lay-up sequence and 0 fibre layer at the boundary.

Analysis and Application of Shock Absorption Measures for High-rise Inpatient Building of a Hospital in High Intensity Fortification Area

A proposed 22-storey hospital building is located in an area with 8-degree seismic fortification and is a reinforced concrete frame-shear wall structure. Through the establishment of structural model, calculation and comparative analysis are carried out by using ETBAS and PERFORM-3D software. The viscous damping wall is used for energy dissipation and damping, and the optimal damping scheme is determined by multi round time history analysis and optimal adjustment of the number and location of dampers.

Electronic and optical properties of borophene and graphene with an adsorbed ionic liquid: A density functional theory study

We present a comparative density functional theory study of the electronic and optical properties of graphene and borophene with an adsorbed ionic liquid. The Dirac cones of these two-dimensional nanostructures are not affected by the presence of the ionic liquid close to these sheets, not even in the borophene one in which a very small charge transfer to the ionic liquid anion is detected. However, Bader analysis and charge density calculations showed that the polarization of the ionic liquid induces a redistribution of the electric charge in both sheets as a consequence of the electromagnetic interaction between the anion and cation of the ionic liquid and the electrons on the two-dimensional materials, the effect being notably stronger in graphene than in borophene. Our calculations reveal that several changes take place in the dielectric constant and electron energy loss spectra, including shifts and damping of plasmon bands, related to electrostatically induced changes in the adsorbent surface electron charge distributions and to plasmon loss channels associated to excitations of electrons in the energy levels of the adsorbed ionic liquid species close to the Fermi level of the surface material. While only minor changes are registered in borophene plasmon spectra and in the IR and visible regions of the graphene spectra, important changes in the graphene ultraviolet C and X-ray spectra are registered due to the existence of IL electronic energy levels close to the Fermi level of graphene that are absent in borophene.

Increasing Collisional Activation of Protein Complexes Using Smaller Aperture Source Sampling Cones on a Synapt Q-IM-TOF Instrument with a Stepwave Source.

Quadrupole ion mobility time-of-flight (Q-IM-TOF) mass spectrometers have revolutionized investigation of native biomolecular complexes. High pressures in the sources of these instruments aid transmission of protein complexes through damping of kinetic energy by collisional cooling. As adducts are removed through collisional heating (declustering), excessive collisional cooling can prevent removal of nonspecific adducts from protein ions, leading to inaccurate mass measurements, broad mass spectral peaks, and obfuscation of ligand binding. We show that reducing the source pressure using smaller aperture source sampling cones (SC) in a Waters Synapt G2-Si instrument increases protein ion heating by decreasing collisional cooling, providing a simple way to enhance removal of adducted salts from soluble proteins (GroEL 14-mer) and detergents from a transmembrane protein complex (heptameric Staphylococcus aureus α-hemolysin, αHL). These experiments are supported by ion heating and cooling simulations which demonstrate reduced collisional cooling at lower source pressures. Using these easily swapped sample cones of different apertures is a facile approach to reproducibly extend the range of activation in Synapt-type instruments.

Influence of the mechanical damage on vibration of a viscothermoelastic circular microplate resonator based on dual-phase-lag heat conduction

We establish a mathematical model of thermally conducting an isotropic, homogeneous, and circular microplate in the context of Kirchhoff’s Love plate theory. We define the governing equations in the context of the generalized dual-phase-lagging model and coupled viscothermoelastic plate. We illustrate the scaled viscothermoelasticity for the case of a circular plate for an aspect ratio for clamped boundary conditions. The bounding plane of the plate has been thermally shocked by ramp heating. We apply the Laplace transform and numerically calculate its inversions. The results are obtained for a ceramic plate. The effects of the damage variables and the thickness of the resonator on the temperature increment distribution are found to be minimal, whereas the effect of the ramp heat parameter on the temperature increment is significant. The damage variables and the thickness of the resonator have significant effects. We determine that the ramp heat parameter can be used as a controller to tune the energy damping.

Exponential Stabilization of Port-Hamiltonian Boundary Control Systems via Energy Shaping

This article is concerned with the exponential stabilization of a class of linear boundary control systems (BCSs) in port-Hamiltonian form through energy shaping. Starting from a first feedback loop that is in charge of modifying the Hamiltonian function of the plant, a second control loop that guarantees exponential convergence to the equilibrium is designed. In this way, a major limitation of standard energy shaping plus damping injection control laws applied to linear port-Hamiltonian BCSs, namely the fact that only asymptotic convergence is assured, has been removed.

Magnetic Energy Transfer and Distribution between Protons and Electrons for Alfvénic Waves at Kinetic Scales in Wavenumber Space

Abstract Turbulent dissipation is considered a main source of heating and acceleration in cosmic plasmas. The alternating current Joule-like term, , is used to measure the energy transfer between electromagnetic fields and particles. Because the electric field depends on the reference frame, in which frame to calculate is an important issue. We compute the scale-dependent energy transfer rate spectrum in wavevector space, and investigate the electric-field fluctuations in two reference frames: in the mean bulk flow frame and in the local bulk flow frame (non-inertial reference frame). Considering Alfvénic waves, we find that , which neglects the contribution of work done by the ion inertial force, is not consistent with the magnetic field energy damping rate (2γδB 2) according to linear Maxwell–Vlasov theory, while is exactly the same as 2γδB 2 in wavenumber space (k ∥, k ⊥), where γ is the linear damping rate. Under typical conditions of solar wind at 1 au, we find in our theoretical calculation that the field energy is mainly converted into proton kinetic energy leaving the residual minor portion for electrons. Although the electrons gain energy in the direction perpendicular to the mean magnetic field, they return a significant fraction of their kinetic energy in the parallel direction. Magnetic-field fluctuations can transfer particle energy between the parallel and perpendicular degrees of freedom. Therefore, and do not solely describe the energy transfer in the parallel direction and perpendicular direction, respectively.

Classical field model for arrays of photon condensates

We introduce a classical phasor model for the description of multimode photon condensates that thermalize through repeated absorptions and reemissions by dye molecules. Thermal equilibrium is expressed through the fluctuation-dissipation relation that connects the energy damping to spontaneous emission fluctuations. We apply our model to a photonic Josephson junction (two coupled wells) and to one- and two-dimensional arrays of photon condensates. In the limit of zero pumping and cavity losses, we recover the thermal equilibrium result, but in the weakly driven-dissipative case in the canonical regime, we find suppressed density and phase fluctuations with respect to the ideal Bose gas.

Mechanical Energy and Equivalent Viscous Damping for Fractional Zener Oscillator

Abstract This paper presents mechanical energy and equivalent viscous damping for a single-degree-of-freedom fractional Zener oscillator. Differential equation of motion is derived in terms of fractional Zener constitutive equation of viscoelastic materials. A virtual fractional oscillator is generated via a state transformation. Then, based on the diffusive model for fractional integrators, the stored energy in fractional derivatives with orders lying in (0, 1) and (2, 3) is determined. Thus, the total mechanical energy in the virtual oscillator is determined. Finally, fractional derivatives are split into three parts: the equivalent viscous damping, equivalent stiffness, and equivalent mass. In this way, the fractional differential equation is simplified into an integer-order differential equation, which is much more convenient to handle in engineering.

Reversible deformation in nanocrystalline TWIP steel during cyclic loading by partial slip reversal and detwinning

Mechanical responses of nanostructured twinning induced plasticity (TWIP) steels have attracted attention owing to their ultra high strength and ductility. A set of molecular dynamics simulations were carried out to characterize and track the atomic structure of Fe–22Mn (wt. %) nanocrystalline TWIP steel during reverse loading (tension-compression). The results show that intrinsic stacking faults and deformation twins which were formed during forward tensile loading up to total strain of 5.8% were eliminated upon subsequent reverse compression loading up to strain of 0.0 %. The current study provides the first simulation evidence of detwinning in nanocrystalline TWIP steel during the reverse loading. The atomic structure and dislocation analysis show that the observed detwinning is due to the dependence of shear stress acting on the trailing and leading partial dislocations on the loading direction. The results show that the Schmid factor of the trailing partial dislocations in compression loading are larger than leading partial dislocations one. The reversible deformation by detwinning could allow for reversible plastic deformation, storage of energy and mechanical damping in micro or nano devices.

Behavior of multidirectional friction dampers

Earthquakes are catastrophic events causing loss of lives, injuries, and extensive losses in properties. Majority of the life and property losses of earthquakes are dependent on the incapabilities of the building stock to resist earthquakes. Although unsuitable design, analyses, and production techniques play a major role as the main reasons for the poor performance of buildings against earthquakes, buildings constructed in accordance with building codes also suffer from the devastating impact of earthquakes. In this context, the lack of proper management and adequate damping of the energy caused by earthquakes is a major cause of structural damage in earthquakes. The efficiency of conventional basic elements in structures with energy damping is very limited and may not be sufficient for the damping of a large amount of earthquake-induced energy. Thanks to the rapid advances in technology and associated engineering techniques, numerous new products, and production and calculation techniques are underway to mitigate the devastating effects of earthquakes on buildings. In this study, it was aimed to theoretically and experimentally investigate the performance of a versatile friction-type seismic damper that eliminates earthquake energy. The damper is designed using a spherical surface friction joint to respond to all loads regardless of the loading direction. The damper can be easily adjusted to the desired capacity by means of bolt tensioning elements. Experiments have been carried out for various shear loads and damping parameters. Furthermore, numerical analysis of the model was carried out by use of the finite element method. The results of this study revealed that the shear load capacity of the device did not change at different frequencies. Analyzing the effect of the equipment on a structure, it was understood that it reduces roof displacement and periods of the structure. The analysis revealed that the damper significantly improved the earthquake performance of the structure.

Dynamics of hot Bose-Einstein condensates: stochastic Ehrenfest relations for number and energy damping

Describing partially-condensed Bose gases poses a long-standing theoretical challenge. We present exact stochastic Ehrenfest relations for the stochastic projected Gross-Pitaevskii equation, including both number and energy damping mechanisms, and all projector terms that arise from the energy cutoff separating system from reservoir. We test the theory by applying it to the center of mass fluctuations of a harmonically trapped prolate system, finding close agreement between c-field simulations and analytical results. The formalism lays the foundation to analytically explore experimentally accessible hot Bose-Einstein condensates.