Energy Technology Data Exchange (ETDEWEB)
Ruiz Lopez, Pablo [Instituto de Investigaciones Electricas, Cuernavaca (Mexico)
1990-12-31
This paper describes a damping criterion that allows realizing in a more convenient form the dynamic analysis of piping and structures in general, subjected to independent stimulations, fabricated in different materials and/or damping devices. This criterion, named composed damping, is applicable to the method of modal superimposition. [Espanol] En este trabajo se describe un criterio de amortiguamiento que permite realizar en una forma mas conveniente el analisis dinamico de tuberias y estructuras en general, sujetas a excitaciones independientes, compuestas de diferentes materiales y/o mecanismos de amortiguamiento. Este criterio, denominado amortiguamiento compuesto, es aplicable en el metodo de superposicion modal.
Energy Technology Data Exchange (ETDEWEB)
Ruiz Lopez, Pablo [Instituto de Investigaciones Electricas, Cuernavaca (Mexico)
1989-12-31
This paper describes a damping criterion that allows realizing in a more convenient form the dynamic analysis of piping and structures in general, subjected to independent stimulations, fabricated in different materials and/or damping devices. This criterion, named composed damping, is applicable to the method of modal superimposition. [Espanol] En este trabajo se describe un criterio de amortiguamiento que permite realizar en una forma mas conveniente el analisis dinamico de tuberias y estructuras en general, sujetas a excitaciones independientes, compuestas de diferentes materiales y/o mecanismos de amortiguamiento. Este criterio, denominado amortiguamiento compuesto, es aplicable en el metodo de superposicion modal.
Stiffness and damping in mechanical design
National Research Council Canada - National Science Library
Rivin, Eugene I
1999-01-01
... important conceptual issues are stiffness of mechanical structures and their components and damping in mechanical systems sensitive to and/or generating vibrations. Stiffness and strength are the most important criteria for many mechanical designs. However, although there are hundreds of books on various aspects of strength, and strength issues ar...
Metallic materials for mechanical damping capacity applications
Crăciun, R. C.; Stanciu, S.; Cimpoeșu, R.; (Dragoș Ursanu, A. I.; Manole, V.; Paraschiv, P.; Chicet, D. L.
2016-08-01
Some metallic materials exhibit good damping capacity of mechanical energy into thermal energy. This property along with the others metallic characteristics make this materials interesting for a big number of applications. These materials can be used as bumpers in different applications including automotive field. Beside grey cast iron and shape memory alloys few new metallic materials are presented for the supposition of high damping capacity. We analyze the causes that increase the internal friction of some metallic materials and possibilities to enhance this property through different mechanical, physical or chemical methods. Shape memory alloys, especially those based on copper, present a different damping capacity on martensite, austenite or transition state. In the transformation range M ↔A, which in case of copper base shape memory alloys is quite large, the metallic intelligent materials present a high internal friction, almost comparable with natural rubber behavior that can transform mechanical energy into thermal energy till a certain value of the external solicitation. These materials can be used as noise or small vibrations bumpers or even as shock absorbers in automotive industry.
Thiol-ene/methacrylate systems for mechanical damping
McNair, Olivia; Senyurt, Askim; Wei, Huanyu; Gould, Trent; Piland, Scott; Hoyle, Charles; Savin, Daniel
2010-03-01
Ternary thiol-ene-methacrylate (TEMA) networks as materials for mechanical energy damping are unique to the sports world. Using a photoinitiation process, TEMA systems are formed via an initial thiol-ene step-growth mechanism along with traditional radical polymerization of acrylate and ene monomers. Final networks have two-part morphologies: acrylate homopolymer sectors imbedded in a multi-component mesh. Several (TEMA) systems have been synthesized and analyzed via thermal and mechanical probing. Initial studies on these ternary systems have shown excellent properties compared to traditional ethylene vinyl alcohol (EVA) copolymers. For example, PEMA networks exhibit glass transition temperatures 33 K higher than EVA, resulting in improved damping at room temperature. This research will help develop relationships between tan delta, glass transition and their effects on mechanical energy damping for ternary (TEMA) systems.
Chen, D
The $\\textbf{DA}$rk $\\textbf{M}$atter $\\textbf{P}$article $\\textbf{E}$xplorer (DAMPE) experiment is a high-energy astroparticle physics satellite mission to search for Dark Matter signatures in space, study the cosmic ray spectrum and composition up to 100 TeV, and perform high-energy gamma astronomy. The launch is planned for end 2015, initially for 3 years, to compliment existing space missions FERMI, AMS and CALET.
Nanoscale shape-memory alloys for ultrahigh mechanical damping.
San Juan, Jose; Nó, Maria L; Schuh, Christopher A
2009-07-01
Shape memory alloys undergo reversible transformations between two distinct phases in response to changes in temperature or applied stress. The creation and motion of the internal interfaces between these phases during such transformations dissipates energy, making these alloys effective mechanical damping materials. Although it has been shown that reversible phase transformations can occur in nanoscale volumes, it is not known whether these transformations have a sample size dependence. Here, we demonstrate that the two phases responsible for shape memory in Cu-Al-Ni alloys are more stable in nanoscale pillars than they are in the bulk. As a result, the pillars show a damping figure of merit that is substantially higher than any previously reported value for a bulk material, making them attractive for damping applications in nanoscale and microscale devices.
Landau damping: the mechanics model and its ultimate entropy gain
International Nuclear Information System (INIS)
Hannay, J H; Kluge, Michel
2011-01-01
Classical mechanics has only been invoked to account for Landau damping in a rather half-hearted way, alongside plasma perturbation theory. In particular this invocation is essential for the study of the saturation, or post-linear (or 'nonlinear') regime of the damping initiated by Dawson and O'Neill. By embracing mechanics wholeheartedly here, with its attendant phase space, one can access results, old and new, cleanly and directly, and with one fewer numerical integration for the post-linear regime. By using a summation technique familiar in semiclassical quantum mechanics (Poisson summation), the one remaining numerical integration can be much improved in accuracy. Also accessible from mechanics is the ultimate entropy gain. Though zero for any finite time (in the absence of coarse graining), the entropy gain is ultimately non-zero (at infinite time the required coarse graining is zero). It is calculated analytically by using the appropriate asymptotics, hitherto not fully exploited.
International Nuclear Information System (INIS)
Chiba, T.; Kobayashi, H.; Kitamura, K.; Ando, K.; Koyanagi, R.
1983-01-01
The objectives of this study are 1) to clarify the damping characteristics and the dynamic stiffness of mechanical snubber, 2) to take the damping characteristics of mechanical snubber into the damping evaluation method obtained in SDREP. Therefore, following vibration tests were conducted. 1) Component test: As a first step, mechanical snubbers were excited with sinusoidal wave, and damping ratio and dynamic stiffness were measured at several loading levels. 2) Piping model test: Second, a 8'' diameter x 16 m length 3-dimensional piping model simulating the supporting conditions of actual piping systems was tested. Damping ratio and made shapes of piping model with mechanical snubbers were measured at several supporting conditions and response levels. From the results of these tests, the damping characteristics and the dynamic stiffness of mechanical snubber can be summarized as follows: 1) The damping effect of mechanical snubber is as strong as that of oil snubber. 2) Mechanical snubber contributes effectively to the damping of piping system, and it is indicated that the damping characteristics of mechanical snubber is applicable to the damping evaluation method obtained in SDREP. (orig./HP)
Classical and quantum mechanics of the damped harmonic oscillator
International Nuclear Information System (INIS)
Dekker, H.
1981-01-01
The relations between various treatments of the classical linearly damped harmonic oscillator and its quantization are investigated. In the course of a historical survey typical features of the problem are discussed on the basis of Havas' classical Hamiltonian and the quantum mechanical Suessmann-Hasse-Albrecht models as coined by the Muenchen/Garching nuclear physics group. It is then shown how by imposing a restriction on the classical trajectories in order to connect the Hamiltonian with the energy, the time-independent Bateman-Morse-Feshbach-Bopp Hamiltonian leads to the time-dependent Caldirola-Kanai Hamiltonian. Canonical quantization of either formulation entails a violation of Heisenberg's principle. By means of a unified treatment of both the electrical and mechanical semi-infinite transmission line, this defect is related to the disregard of additional quantum fluctuations that are intrinsically connected with the dissipation. The difficulties of these models are discussed. Then it is proved that the Bateman dual Hamiltonian is connected to a recently developed complex symplectic formulation by a simple canonical transformation. (orig.)
Cellular Magnesium Matrix Foam Composites for Mechanical Damping Applications
Shunmugasamy, Vasanth Chakravarthy; Mansoor, Bilal; Gupta, Nikhil
2016-01-01
The damping characteristics of metal alloys and metal matrix composites are relevant to the automotive, aerospace, and marine structures. Use of lightweight materials can help in increasing payload capacity and in decreasing fuel consumption. Lightweight composite materials possessing high damping capabilities that can be designed as structural members can greatly benefit in addressing these needs. In this context, the damping properties of lightweight metals such as aluminum and magnesium and their respective composites have been studied in the existing literature. This review focuses on analyzing the damping properties of aluminum and magnesium alloys and their cellular composites. The damping properties of various lightweight alloys and composites are compared on the basis of their density to understand the potential for weight saving in structural applications. Magnesium alloys are observed to possess better damping properties in comparison to aluminum. However, aluminum matrix syntactic foams reinforced with silicon carbide hollow particles possess a damping capacity and density comparable to magnesium alloy. By using the data presented in the study, composites with specific compositions and properties can be selected for a given application. In addition, the comparison of the results helps in identifying the areas where attention needs to be focused to address the future needs.
Comparison of Damping Mechanisms for Transverse Waves in Solar Coronal Loops
Energy Technology Data Exchange (ETDEWEB)
Montes-Solís, María; Arregui, Iñigo, E-mail: mmsolis@iac.es [Instituto de Astrofísica de Canarias, E-38205 La Laguna, Tenerife (Spain)
2017-09-10
We present a method to assess the plausibility of alternative mechanisms to explain the damping of magnetohydrodynamic transverse waves in solar coronal loops. The considered mechanisms are resonant absorption of kink waves in the Alfvén continuum, phase mixing of Alfvén waves, and wave leakage. Our methods make use of Bayesian inference and model comparison techniques. We first infer the values for the physical parameters that control the wave damping, under the assumption of a particular mechanism, for typically observed damping timescales. Then, the computation of marginal likelihoods and Bayes factors enable us to quantify the relative plausibility between the alternative mechanisms. We find that, in general, the evidence is not large enough to support a single particular damping mechanism as the most plausible one. Resonant absorption and wave leakage offer the most probable explanations in strong damping regimes, while phase mixing is the best candidate for weak/moderate damping. When applied to a selection of 89 observed transverse loop oscillations, with their corresponding measurements of damping timescales and taking into account data uncertainties, we find that positive evidence for a given damping mechanism is only available in a few cases.
Comparison of Damping Mechanisms for Transverse Waves in Solar Coronal Loops
International Nuclear Information System (INIS)
Montes-Solís, María; Arregui, Iñigo
2017-01-01
We present a method to assess the plausibility of alternative mechanisms to explain the damping of magnetohydrodynamic transverse waves in solar coronal loops. The considered mechanisms are resonant absorption of kink waves in the Alfvén continuum, phase mixing of Alfvén waves, and wave leakage. Our methods make use of Bayesian inference and model comparison techniques. We first infer the values for the physical parameters that control the wave damping, under the assumption of a particular mechanism, for typically observed damping timescales. Then, the computation of marginal likelihoods and Bayes factors enable us to quantify the relative plausibility between the alternative mechanisms. We find that, in general, the evidence is not large enough to support a single particular damping mechanism as the most plausible one. Resonant absorption and wave leakage offer the most probable explanations in strong damping regimes, while phase mixing is the best candidate for weak/moderate damping. When applied to a selection of 89 observed transverse loop oscillations, with their corresponding measurements of damping timescales and taking into account data uncertainties, we find that positive evidence for a given damping mechanism is only available in a few cases.
Mechanism of biological control of Rhizoctonia damping-off of ...
African Journals Online (AJOL)
MOHSEN
2014-01-29
Jan 29, 2014 ... from soil, causing severe damping-off disease to radish and cucumber was .... concentrations of elements in samples were expressed in milli- equivalent per ..... radioactive analysis, is a polysaccharide synthesized in the golgi ...
The ROSETTA PHILAE Lander damping mechanism as probe for the Comet soil strength.
Roll, R.
2015-10-01
The ROSETTA Lander is equipped with an one axis damping mechanism to dissipate kinetic energy during the touch down. This damping is necessary to avoid damages to the Lander by a hard landing shock and more important to avoid re-bouncing from ground with high velocity. The damping mechanism works best for perpendicular impact, which means the velocity vector is parallel to the damper axis and all three feet touch the ground at the same time. That is usually not the case. Part of the impact energy can be transferred into rotational energy at ground contact if the impact is not perpendicular. This energy will lift up the Lander from the ground if the harpoons and the hold down thruster fail, as happen in mission. The damping mechanism itself is an electrical generator, driven by a spindle inside a telescopic tube. This tube was extended in mission for landing by 200mm. A maximum damping length of 140mm would be usually required to compensate a landing velocity of 1m/s, if the impact happens perpendicular on hard ground. After landing the potentiometer of the telescopic tube reading shows a total damping length of only 42,5mm. The damping mechanism and the overall mechanical behavior of the Lander at touch down are well tested and characterized and transferred to a multi-body computer model. The incoming and outgoing flightpath of PHILAE allow via computer-simulation the reconstruction of the touch down. It turns out, that the outgoing flight direction is dominated by the local ground slope and that the damping length is strongly dependent on the soil strength. Damping of soft comet ground must be included to fit the damping length measured. Scenario variations of the various feet contact with different local surface features (stone or regolith) and of different soil models finally lead to a restricted range for the soil strength at the touch down area.
Statistical mechanics of quantum one-dimensional damped harmonic oscillator
International Nuclear Information System (INIS)
Borges, E.N.M.; Borges, O.N.; Ribeiro, L.A.A.
1985-01-01
We calculate the thermal correlation functions of the one-dimensional damped harmonic oscillator in contact with a reservoir, in an exact form by applying Green's function method. In this way the thermal fluctuations are incorporated in the Caldirola-Kanai Hamiltonian
Damping mechanisms and heating scenarii in the ICRF
International Nuclear Information System (INIS)
Jacquinot, J.; Lapierre, Y.
1980-09-01
A wave damping and heating model is presented. It permits to treat a wide range of plasma parameters and complex ion species composition. Applied to JET parameters, two selected wave scenarii are found to allow a great flexibility, in particular with respect to complex gas composition. A major results is the possibility of single pass absorption
Electroresponsive Aqueous Silk Protein As “Smart” Mechanical Damping Fluid
2015-01-01
Here we demonstrate the effectiveness of an electroresponsive aqueous silk protein polymer as a smart mechanical damping fluid. The aqueous polymer solution is liquid under ambient conditions, but is reversibly converted into a gel once subjected to an electric current, thereby increasing or decreasing in viscosity. This nontoxic, biodegradable, reversible, edible fluid also bonds to device surfaces and is demonstrated to reduce friction and provide striking wear protection. The friction and mechanical damping coefficients are shown to modulate with electric field exposure time and/or intensity. Damping coefficient can be modulated electrically, and then preserved without continued power for longer time scales than conventional “smart” fluid dampers. PMID:24750065
Application of damping mechanism model and stacking fault probability in Fe-Mn alloy
International Nuclear Information System (INIS)
Huang, S.K.; Wen, Y.H.; Li, N.; Teng, J.; Ding, S.; Xu, Y.G.
2008-01-01
In this paper, the damping mechanism model of Fe-Mn alloy was analyzed using dislocation theory. Moreover, as an important parameter in Fe-Mn based alloy, the effect of stacking fault probability on the damping capacity of Fe-19.35Mn alloy after deep-cooling or tensile deformation was also studied. The damping capacity was measured using reversal torsion pendulum. The stacking fault probability of γ-austenite and ε-martensite was determined by means of X-ray diffraction (XRD) profile analysis. The microstructure was observed using scanning electronic microscope (SEM). The results indicated that with the strain amplitude increasing above a critical value, the damping capacity of Fe-19.35Mn alloy increased rapidly which could be explained using the breakaway model of Shockley partial dislocations. Deep-cooling and suitable tensile deformation could improve the damping capacity owning to the increasing of stacking fault probability of Fe-19.35Mn alloy
Nontrivial effects of high-frequency excitation for strongly damped mechanical systems
DEFF Research Database (Denmark)
Fidlin, Alexander; Thomsen, Jon Juel
2008-01-01
Some non-trivial effects are investigated, which can occur if strongly damped mechanical systems are subjected to strong high-frequency (HF) excitation. The main result is a theoretical prediction, supported by numerical simulation, that for such systems the (quasi-)equilibrium states can change...... that can be substantial depending on the strength of the HF excitation) for finite values of the damping. The analysis is focused on the differences between the classic results for weakly damped systems, and new effects for which the strong damping terms are responsible. The analysis is based on a slightly...... modified averaging technique, and includes an elementary example of an elliptically excited pendulum for illustration, alongside with a generalization to a broader class of strongly damped dynamical systems with HF excitation. As an application example, the nontrivial behavior of a classical optimally...
Nontrivial effects of high-frequency excitation for strongly damped mechanical systems
DEFF Research Database (Denmark)
Fidlin, Alexander; Thomsen, Jon Juel
Some nontrivial effects are investigated, which can occur if strongly damped mechanical systems are subjected to strong high-frequency (HF) excitation. The main result is a theoretical prediction, supported by numerical simulation, that for such systems the (quasi-)equilibrium states can change...... that can be substantial (depending on the strength of the HF excitation) for finite values of the damping. The analysis is focused on the differences between the classic results for weakly damped systems, and new effects for which the strong damping terms are responsible. The analysis is based...... on a slightly modified averaging technique, and includes an elementary example of an elliptically excited pendulum for illustration, alongside with a generalization to a broader class of strongly damped dynamical systems with HF excitation. As an application example, the nontrivial behavior of a classical...
Feasibility study of a large-scale tuned mass damper with eddy current damping mechanism
Wang, Zhihao; Chen, Zhengqing; Wang, Jianhui
2012-09-01
Tuned mass dampers (TMDs) have been widely used in recent years to mitigate structural vibration. However, the damping mechanisms employed in the TMDs are mostly based on viscous dampers, which have several well-known disadvantages, such as oil leakage and difficult adjustment of damping ratio for an operating TMD. Alternatively, eddy current damping (ECD) that does not require any contact with the main structure is a potential solution. This paper discusses the design, analysis, manufacture and testing of a large-scale horizontal TMD based on ECD. First, the theoretical model of ECD is formulated, then one large-scale horizontal TMD using ECD is constructed, and finally performance tests of the TMD are conducted. The test results show that the proposed TMD has a very low intrinsic damping ratio, while the damping ratio due to ECD is the dominant damping source, which can be as large as 15% in a proper configuration. In addition, the damping ratios estimated with the theoretical model are roughly consistent with those identified from the test results, and the source of this error is investigated. Moreover, it is demonstrated that the damping ratio in the proposed TMD can be easily adjusted by varying the air gap between permanent magnets and conductive plates. In view of practical applications, possible improvements and feasibility considerations for the proposed TMD are then discussed. It is confirmed that the proposed TMD with ECD is reliable and feasible for use in structural vibration control.
Damping capacity and dynamic mechanical characteristics of the plasma-sprayed coatings
International Nuclear Information System (INIS)
Yu Liming; Ma Yue; Zhou Chungen; Xu Huibin
2005-01-01
The damping properties and dynamic mechanical performance of NiCrAlY coating, FeCrMo ferromagnetic coating, AlCuFeCr quasicrystalline coating and nanostructured ZrO 2 ceramic coating, which were prepared by plasma-spray method, were investigated. The measuring results of the dynamic mechanical thermal analyzer (DMTA) and the flexural resonance testing method show that the damping capacity (Q -1 ) of the coated sample has a notable improvement compared to the substrate, while the dynamic modulus has a dramatic decrease. The resonance frequency of the coated cantilever beam structure shifted to high-frequency, and the resonance amplitude, especially high mode resonance, was dramatically attenuated. The internal friction peaks were observed in the Q -1 -temperature spectrogram and a normal amplitude effects were shown in the coated samples damping characteristics. The damping mechanism based on the interaction between substrate and coating layer, and the microstructure of the coated sample were also discussed in this paper
Indefinite damping in mechanical systems and gyroscopic stabilization
DEFF Research Database (Denmark)
Kliem, Wolfhard; Pommer, Christian
2009-01-01
This paper deals with gyroscopic stabilization of the unstable system Mx + D(x) over dot + K-x = 0, with positive definite mass and stiffness matrices M and K, respectively, and an indefinite damping matrix D. The main question if for which skew-symmetric matrices G the system Mx (D+ G)(x) over dot...... + K-x = 0 can become stable? After investigating special cases we find an appropriat solution of the Lyapunov matrix equation for the general case. Examples show the deviation of the stability limit found by the Lyapunov method from the exact value....
Emergent large mechanical damping in ferroelastic-martensitic systems driven by disorder
Ni, Yan; Zhang, Zhen; Fang, Minxia; Hao, Yanshuang; Ding, Xiangdong; Otsuka, Kazuhiro; Ren, Xiaobing
2018-05-01
Disorders and point defects strongly interplay with the phase transition and alter the properties of ferroelastic-martensitic systems. Unusual static and quasistatic behaviors, such as time-dependent phase transitions, are discovered when disorders are introduced. However, the role of disorders on the ferroelastic system in vibrational environments at moderate frequency is rarely known, investigation of which could further shed light on their application as mechanical damping materials. Here we present the emergence of large damping capacity in ferroelastic-martensitic systems [including both the T i50 -xN i50 +x alloy and (C a1 -xS rx) Ti O3 ceramics] by introducing disorder (i.e., substitutional Ni and Sr, respectively). As the level disorder increases, the damping capacity of both systems raises and eventually reaches a maximum when long-range-ordered martensite tends to vanish. Moreover, near the disorder-induced phase boundary, we observe a large mechanical damping in ferroelastic ceramics (C a1 -xS rx) Ti O3 with a figure of merit ˜2 GP a1 /2 . Microscopic and dynamic investigations indicate that such damping plateau could result from the competing evolution of density and mobility of domain boundaries when disorder is introduced. Our work provides a degree of freedom to develop ferroelastic damping materials and a potential way to tune domain-boundary-mediated functionalities for other ferroic materials.
Damping forces-a friend or a foe in explaining mechanical motion?
International Nuclear Information System (INIS)
Bartos, JirI; Musilova, Jana
2006-01-01
This paper presents simple, cheap, easily accessible and, for students, impressive demonstration experiments for three typical examples of physical systems for which damping forces ought to be involved in the equations of motion: a body falling in air, a damped mechanical oscillator, and Foucault currents. The various models of such forces are studied using an elementary physical and mathematical approach. It appears, maybe as a slightly surprising result, that a commonly used model of damping forces in mechanics-air drag force linearly depending on velocity-is not realistic in many typical situations. Equations of motion are solved numerically with standard software packages, even in cases where an analytical solution exists. Thus, the explanation of solved problems is on a level corresponding to an undergraduate university course in general physics. The results of these demonstration experiments are compared with the graphical outputs of numerical solutions
An experimental study of a new multi-bunch damping mechanism in PETRA
International Nuclear Information System (INIS)
Heins, D.; Kohaupt, R.D.; Kriens, W.; Leneke, M.; Matthiesen, K.H.; Musfeldt, H.; Paetzold, S.
1986-12-01
In this article we describe the experiment which has been performed in PETRA in order to demonstrate the existence of the damping mechanism based on a combination of a narrow-band feedback system and frequency splitting between bunches. (orig./HSI)
Damping forces—a friend or a foe in explaining mechanical motion?
Bartos, Jirí; Musilová, Jana
2006-03-01
This paper presents simple, cheap, easily accessible and, for students, impressive demonstration experiments for three typical examples of physical systems for which damping forces ought to be involved in the equations of motion: a body falling in air, a damped mechanical oscillator, and Foucault currents. The various models of such forces are studied using an elementary physical and mathematical approach. It appears, maybe as a slightly surprising result, that a commonly used model of damping forces in mechanics—air drag force linearly depending on velocity—is not realistic in many typical situations. Equations of motion are solved numerically with standard software packages, even in cases where an analytical solution exists. Thus, the explanation of solved problems is on a level corresponding to an undergraduate university course in general physics. The results of these demonstration experiments are compared with the graphical outputs of numerical solutions.
Takács, Gergely
2012-01-01
Real-time model predictive controller (MPC) implementation in active vibration control (AVC) is often rendered difficult by fast sampling speeds and extensive actuator-deformation asymmetry. If the control of lightly damped mechanical structures is assumed, the region of attraction containing the set of allowable initial conditions requires a large prediction horizon, making the already computationally demanding on-line process even more complex. Model Predictive Vibration Control provides insight into the predictive control of lightly damped vibrating structures by exploring computationally efficient algorithms which are capable of low frequency vibration control with guaranteed stability and constraint feasibility. In addition to a theoretical primer on active vibration damping and model predictive control, Model Predictive Vibration Control provides a guide through the necessary steps in understanding the founding ideas of predictive control applied in AVC such as: · the implementation of ...
Research on low strain magnetic mechanical hysteresis damping performance of Fe-15Cr-3Mo-0.5Si alloy
International Nuclear Information System (INIS)
Wang, Hui; Huang, Huawei; Hong, Xiaofeng; Yin, Changgeng; Huang, Zhaohua; Chen, Le
2015-01-01
Highlights: • Heat treatment system has a great effect on the alloy damping performance. • Damping performance does not improve monotonously with temperature. • Furnace cooling is higher than that of alloy after air cooling. • There is an optimum annealing temperature and grain size to obtain high damping. - Abstract: This paper studies the preparation of Fe-15Cr-3Mo-0.5Si alloy by using vacuum induction melting furnace and vacuum annealing furnace, the damping performance of which in different heat treatment states is tested with dynamic mechanical thermal analyzer (DMA). Through microstructure observation with metallographic microscope (OM), grain boundary observation with scanning electron microscopy (SEM), phase structure analysis with X-ray diffraction (XRD) and internal stress of S-B model analysis, the effect law of annealing temperature, types of cooling, holding time and grain sizes on the damping performance of alloy and the related mechanism can be concluded as follows. The annealing temperature and grain sizes have a significant impact on the damping strain amplitude as well as the magnetic and mechanical damping performance of this ferromagnetic alloy. Proper annealing temperature and grain size is the necessary condition to get high damping performance of the alloy. It is not conducive to improvement of the damping performance if the annealing temperature is too high or too low and the grain size is too small or too large. For Fe-15Cr-3Mo-0.5Si alloy, within the range of the low strain amplitude, alloy damping performance does not improve monotonously with the increase of the annealing temperature and grain size. The maximum value appears at the annealing temperature of 1100 °C/1 h with the grain size of about 300 μm. At high annealing temperature of 1100 °C, the damping performance of alloy in the slow cooling furnace is higher than that with air cooling treatment. The extension or shortening of the holding time, to a certain extent
Research on low strain magnetic mechanical hysteresis damping performance of Fe-15Cr-3Mo-0.5Si alloy
Energy Technology Data Exchange (ETDEWEB)
Wang, Hui, E-mail: qinghe5525@163.com; Huang, Huawei; Hong, Xiaofeng; Yin, Changgeng; Huang, Zhaohua; Chen, Le
2015-02-15
Highlights: • Heat treatment system has a great effect on the alloy damping performance. • Damping performance does not improve monotonously with temperature. • Furnace cooling is higher than that of alloy after air cooling. • There is an optimum annealing temperature and grain size to obtain high damping. - Abstract: This paper studies the preparation of Fe-15Cr-3Mo-0.5Si alloy by using vacuum induction melting furnace and vacuum annealing furnace, the damping performance of which in different heat treatment states is tested with dynamic mechanical thermal analyzer (DMA). Through microstructure observation with metallographic microscope (OM), grain boundary observation with scanning electron microscopy (SEM), phase structure analysis with X-ray diffraction (XRD) and internal stress of S-B model analysis, the effect law of annealing temperature, types of cooling, holding time and grain sizes on the damping performance of alloy and the related mechanism can be concluded as follows. The annealing temperature and grain sizes have a significant impact on the damping strain amplitude as well as the magnetic and mechanical damping performance of this ferromagnetic alloy. Proper annealing temperature and grain size is the necessary condition to get high damping performance of the alloy. It is not conducive to improvement of the damping performance if the annealing temperature is too high or too low and the grain size is too small or too large. For Fe-15Cr-3Mo-0.5Si alloy, within the range of the low strain amplitude, alloy damping performance does not improve monotonously with the increase of the annealing temperature and grain size. The maximum value appears at the annealing temperature of 1100 °C/1 h with the grain size of about 300 μm. At high annealing temperature of 1100 °C, the damping performance of alloy in the slow cooling furnace is higher than that with air cooling treatment. The extension or shortening of the holding time, to a certain extent
Dean, Robert; Flowers, George; Sanders, Nicole; MacAllister, Ken; Horvath, Roland; Hodel, A. S.; Johnson, Wayne; Kranz, Michael; Whitley, Michael
2005-05-01
Some harsh environments, such as those encountered by aerospace vehicles and various types of industrial machinery, contain high frequency/amplitude mechanical vibrations. Unfortunately, some very useful components are sensitive to these high frequency mechanical vibrations. Examples include MEMS gyroscopes and resonators, oscillators and some micro optics. Exposure of these components to high frequency mechanical vibrations present in the operating environment can result in problems ranging from an increased noise floor to component failure. Passive micromachined silicon lowpass filter structures (spring-mass-damper) have been demonstrated in recent years. However, the performance of these filter structures is typically limited by low damping (especially if operated in near-vacuum environments) and a lack of tunability after fabrication. Active filter topologies, such as piezoelectric, electrostrictive-polymer-film and SMA have also been investigated in recent years. Electrostatic actuators, however, are utilized in many micromachined silicon devices to generate mechanical motion. They offer a number of advantages, including low power, fast response time, compatibility with silicon micromachining, capacitive position measurement and relative simplicity of fabrication. This paper presents an approach for realizing active micromachined mechanical lowpass vibration isolation filters by integrating an electrostatic actuator with the micromachined passive filter structure to realize an active mechanical lowpass filter. Although the electrostatic actuator can be used to adjust the filter resonant frequency, the primary application is for increasing the damping to an acceptable level. The physical size of these active filters is suitable for use in or as packaging for sensitive electronic and MEMS devices, such as MEMS vibratory gyroscope chips.
Directory of Open Access Journals (Sweden)
M. Haghgo
2007-08-01
Full Text Available Utilizing polymeric materials for damping mechanical waves is of great importance in various fields of applications such as military camouflage, prevention of structural vibrational energy transfer, and noise attenuation. This ability originates from segmental dynamics of chain-like polymer molecules. Damping properties of styrene-butadiene rubbercontaining 10 wt% of monosize polystyrene particles with different diameters (from 80 nm to 500 μm was investigated in the frequency range of vibration, sound, and ultrasound via dynamic mechanical thermal analysis, normalsound adsorption test, and ultrasound attenuation coefficient measurement. The obtained results indicated that for different systems, containing different sizes of polystyrene particles, the area under the damping curve does not show significant change comparing to the neat SBR in the frequency range studied. However, addition of polystyrene particles, specifically nanosized particles, resulted in emergence of a secondary glass transition temperature which could be attributed to the modified dynamics of a layer of matrix molecules near the surface of PS particles. In the range of sound frequency, 0.5 to 6.3 kHz, the maximum damping was observed for the system containing polystyrene nanoparticles. However the single damping curve of neat SBR was separated into two or even three distinct curves owing to the presence of the particles. The maximum damping in the ultrasound frequency range was found for the system containing 0.5 mm polystyrene particles. This is attributed to different contributions from matrix chains dynamics and the reflection of mechanical waves from particles-matrix interface at different frequency ranges. On other words, the increase in the glass transition temperature of the elastomeric matrix phase with increasing the mechanical wave frequency causes a reduction in the contribution from matrix chains dynamics while the contribution due to diffraction from dispersed
Dirksz, D. A.; Scherpen, J. M. A.; Ortega, R.
2008-01-01
A dynamic extension for position feedback of port-Hamiltonian mechanical systems is studied. First we look at the consequences for the matching equations when applying Interconnection and Damping Assignment Passivity-Based Control (IDA-PBC). Then we look at the possibilities of asymptotically
Directory of Open Access Journals (Sweden)
Giuseppe Catania
2018-02-01
Full Text Available The damping behaviour of multi-layer composite mechanical components, shown by recent research and application papers, is analyzed. A local dissipation mechanism, acting at the interface between any two different layers of the composite component, is taken into account, and a beam model, to be used for validating the known experimental results, is proposed. Multi-layer prismatic beams, consisting of a metal substrate and of some thin coated layers exhibiting variable stiffness and adherence properties, are considered in order to make it possible to study and validate this assumption. A dynamical model, based on a simple beam geometry but taking into account the previously introduced local dissipation mechanism and distributed visco-elastic constraints, is proposed. Some different application examples of specific multi-layer beams are considered, and some numerical examples concerning the beam free and forced response are described. The influence of the multilayer system parameters on the damping behaviour of the free and forced response of the composite beam is investigated by means of the definition of some damping estimators. Some effective multi-coating configurations, giving a relevant increase of the damping estimators of the coated structure with respect to the same uncoated structure, are obtained from the model simulation, and the results are critically discussed.
Damping behavior of AlxCoCrFeNi high-entropy alloys by a dynamic mechanical analyzer
International Nuclear Information System (INIS)
Ma, S.G.; Liaw, P.K.; Gao, M.C.; Qiao, J.W.; Wang, Z.H.; Zhang, Y.
2014-01-01
Highlights: • The Al content is related with structural relaxation and damping capability. • Dynamic modulus is insensitive to the frequency especially for storage modulus. • Several internal-friction peaks are observed in the Al-free or Al-lean alloys. • The damping behavior is proposed to be strongly relied on the level of ordering. - Abstract: For the first time, the damping behavior of high-entropy alloys was studied using the dynamic-mechanical analyzer, over a continuous heating temperature from room temperature to 773 K, at a given frequency range from 1 to 16 Hz in model alloys Al x CoCrFeNi (x = 0, 0.25, 0.5, 0.75, and 1). The experimental results reveal that the Al-rich alloys have a much smaller elastic storage-modulus amplitude over the temperature and thus a larger resistance to structural relaxation, while the Al-free and Al-lean alloys exhibit a much higher loss tangent and thus a much higher damping capability. Overall the elastic storage modulus decreases while the loss tangent increases with increasing the temperature, but little dependence was observed for the frequency. Several visible internal-friction peaks were presented in the face-centered cubic alloys, whose positions and heights are independent of the frequency. The damping capability of these alloys can be comparable to or even overwhelm the conventional Fe–Al alloys. The damping behavior above was proposed to be agreeable with the level of ordering (η) of alloys characterized by two proposed parameters (the relative-entropy effect, Ω, and the atomic-size difference, δ)
Influence of W-phase on mechanical properties and damping capacity of Mg–Zn–Y–Nd–Zr alloys
Energy Technology Data Exchange (ETDEWEB)
Feng, Hao, E-mail: haofeng804@gmail.com [College of Science, Hebei North University, Zhangjiakou 075000, Hebei (China); Yang, Yang [College of Science, Hebei North University, Zhangjiakou 075000, Hebei (China); Chang, Haixia [College of Law and Politics, Hebei North University, Zhangjiakou 075000 (China)
2014-07-15
This work mainly investigated the influence of W-phase on the mechanical properties and damping capacities of as-cast Mg–Zn–Y–Nd–Zr alloys with Zn/RE (rare element) ratio about 1.0. Obtained results indicate that the alloys with Zn and RE addition are composed of α-Mg matrix and W-phase. With the contents of Zn and RE increasing, the diffraction peaks of W-phase are gradually intensified and the morphology of W-phase transforms from fine-network microstructure to coarse-network microstructure. The tensile strength and fracture mechanism are strongly dependent on the quality of W-phase and the alloy with W-phase content of 8.0% has the highest strength as a result of strong atomic bonding between the W-phase and the Mg matrix. The damping capacities of Mg–Zn–Y–Nd–Zr alloys decrease gradually with the increasing amount of W-phase and then maintain at high level at high strain amplitude. The decline of damping capacity can be explained by the forming of W-phase, which makes more phases and interfaces form in the alloys. And the mobile dislocation densities in the alloys increase as residual stress at the interface of W-phase/Mg matrix and long dislocations generate in the α-Mg matrix. Therefore, the damping of alloy with high W-phase content improves accordingly with the increasing amount of moving dislocations.
Directory of Open Access Journals (Sweden)
A. Karami Mohammadi
2015-07-01
Full Text Available : In this paper, a nonlinear model of clamped-clamped microbeam actuated by electrostatic load with stretching and thermoelastic effects is presented. Free vibration frequency is calculated by discretization based on DQ method. Frequency is a complex value due to the thermoelastic effect that dissipates the energy. By separating the real and imaginary parts of frequency, quality factor of thermoelastic damping is calculated. Both stretching and thermoelastic effects are validated against the results of the reference papers. The variations of thermoelastic damping versus elasticity modulus, coefficient of thermal expansion and geometrical parameters such as thickness, gap distance, and length are investigated and these results are compared in the linear and nonlinear models for high values of voltage. Also, this paper shows that since for high values of electrostatic voltage the linear model reveals a large error for calculating the thermoelastic damping, the nonlinear model should be used for this purpose.
Fay, Temple H.
2012-01-01
Quadratic friction involves a discontinuous damping term in equations of motion in order that the frictional force always opposes the direction of the motion. Perhaps for this reason this topic is usually omitted from beginning texts in differential equations and physics. However, quadratic damping is more realistic than viscous damping in many…
International Nuclear Information System (INIS)
Escande, D F; Elskens, Yves; Doveil, F
2015-01-01
The derivation of Debye shielding and Landau damping from the N-body description of plasmas is performed directly by using Newton’s second law for the N-body system. This is done in a few steps with elementary calculations using standard tools of calculus and no probabilistic setting. Unexpectedly, Debye shielding is encountered together with Landau damping. This approach is shown to be justified in the one-dimensional case when the number of particles in a Debye sphere becomes large. The theory is extended to accommodate a correct description of trapping and chaos due to Langmuir waves. On top of their well-known production of collisional transport, the repulsive deflections of electrons are shown to produce shielding, in such a way that each particle is shielded by all other ones, while keeping in uninterrupted motion. (paper)
Microscopic nuclear-dissipation mechanism as damping of collective motion in the second RPA
International Nuclear Information System (INIS)
Yannouleas, C.; Dworzecka, M.; Griffin, J.J.
1982-01-01
A microscopic model for the damping of the one-phonon RPA collective state, absolute value c > = Q/sub c/ 0 > /sub S//sub R/, has been previously described. This one-phonon RPA collective state is defined within a restricted subspace, S/sub R/, of the discrete 1p-1h structure. Its damping is described within an extended subspace, S = S/sub R/ + S/sub A/, by the time evolution of a wave packet according to the RPA and the Second RPA approximations of the complete Schroedinger equation when initialized with the one-phonon state. The one-phonon state, however, is unable to describe time-varying oscillations of the mean field. Such oscillations require wave packets formed by linear superposition of the RPA many-phonon eigenstates. Coherent time-varying oscillations of the mean field (multi-phonon initial states) are discussed
International Nuclear Information System (INIS)
Ware, A.G.
1985-01-01
Studies are being conducted at the Idaho National Engineering Laboratory to determine whether an increase in the damping values used in seismic structural analyses of nuclear piping systems is justified. Increasing the allowable damping would allow fewer piping supports which could lead to safer, more reliable, and less costly piping systems. Test data from availble literature were examined to determine the important parameters contributing to piping system damping, and each was investigated in separate-effects tests. From the combined results a world pipe damping data bank was established and multiple regression analyses performed to assess the relative contributions of the various parameters. The program is being extended to determine damping applicable to higher frequency (33 to 100 Hz) fluid-induced loadings. The goals of the program are to establish a methodology for predicting piping system damping and to recommend revised guidelines for the damping values to be included in analyses
Damping mechanisms of high-lying single-particle states in 91Nb
International Nuclear Information System (INIS)
Molen, H. K. T. van der; Berg, A. M. van den; Harakeh, M. N.; Hunyadi, M.; Kalantar-Nayestanaki, N.; Akimune, H.; Daito, I.; Fujimura, H.; Ihara, F.; Inomata, T.; Ishibashi, K.; Yoshida, H.; Yosoi, M.; Fujita, Y.; Fujiwara, M.; Jaenecke, J.; O'Donnell, T. W.; Laurent, H.; Lhenry, I.; Rodin, V. A.
2007-01-01
Decay by proton emission from high-lying states in 91 Nb, populated in the 90 Zr(α,t) reaction at E α =180 MeV, has been investigated. Decay to the ground state and semidirect decay to the low-lying (2 + ,5 - , and 3 - ) phonon states in 90 Zr were observed. It was found that these phonon states play an important role in the damping process of the single-particle states. An optical-model coupled-channel approach was used successfully to describe the direct and semidirect parts of the decay
Energy Technology Data Exchange (ETDEWEB)
Lee, Kanghee; Kang, Heungseok; Oh, Dongseok; Yoon, Kyungho; Kim, Hyungkyu; Kim, Jaeyong [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)
2013-10-15
This paper summary the fuel assembly damping data in air/in still water/under flow, released from foreign fuel vendors, compared our data with the published data. Some technical issues in fuel assembly damping measurement testing are also briefly discussed. Understanding of each fuel assembly damping mechanisms according to the surrounding medium and flow velocity can support the fuel design improvement in fuel assembly dynamics and structural integrity aspect. Because the upgraded requirements of the newly-developed advanced reactor system will demands to minimize fuel design margin in integrity evaluation, reduction in conservatism of fuel assembly damping can contribute to alleviate the fuel design margin for sure. Damping is an energy dissipation mechanism in a vibrating mechanical structure and prevents a resonant structure from having infinite vibration amplitudes. The sources of fuel assembly damping are various from support friction to flow contribution, and it can be increased by the viscosity or drag of surrounding fluid medium or the average velocity of water flowing. Fuel licensing requires fuel design evaluation in transient or accidental condition. Dynamic response analysis of fuel assembly is to show fuel integrity and requires information on assembly-wise damping in dry condition and under wet or water flowing condition. However, damping measurement test for the full-scale fuel assembly prototype is not easy to carry out because of the scale (fuel prototype, test facility), unsteadiness of test data (scattering, random sampling and processing), instrumentation under water flowing (water-proof response measurement), and noise. LWR fuel technology division in KAERI is preparing the infra structure for damping measurement test of full-scale fuel assembly, to support fuel industries and related research activities. Here is a preliminary summary of fuel assembly damping, published in the literature. Some technical issues in fuel assembly damping
Fay, Temple H.
2012-01-01
Viscous damping is commonly discussed in beginning differential equations and physics texts but dry friction or Coulomb friction is not despite dry friction being encountered in many physical applications. One reason for avoiding this topic is that the equations involve a jump discontinuity in the damping term. In this article, we adopt an energy…
International Nuclear Information System (INIS)
Rees, John; Chao, Alexander
2008-01-01
Landau damping, as the term is used in accelerator science, is a physical process in which an ensemble of harmonic oscillators--an accelerator beam, for example--that would otherwise be unstable is stabilized by a spread in the natural frequencies of the oscillators. This is a study of the most basic aspects of that process. It has two main goals: to gain a deeper insight into the mechanism of Landau damping and to find the coherent motion of the ensemble and thus the dependence of the total damping rate on the frequency spread
Unwin, A P; Hine, P J; Ward, I M; Fujita, M; Tanaka, E; Gusev, A A
2018-02-06
The development of new materials with reduced noise and vibration levels is an active area of research due to concerns in various aspects of environmental noise pollution and its effects on health. Excessive vibrations also reduce the service live of the structures and limit the fields of their utilization. In oscillations, the viscoelastic moduli of a material are complex and it is their loss part - the product of the stiffness part and loss tangent - that is commonly viewed as a figure of merit in noise and vibration damping applications. The stiffness modulus and loss tangent are usually mutually exclusive properties so it is a technological challenge to develop materials that simultaneously combine high stiffness and high loss. Here we achieve this rare balance of properties by filling a solid polymer matrix with rigid inorganic spheres coated by a sub-micron layer of a viscoelastic material with a high level of internal friction. We demonstrate that this combination can be experimentally realised and that the analytically predicted behaviour is closely reproduced, thereby escaping the often termed 'Ashby' limit for mechanical stiffness/damping trade-off and offering a new route for manufacturing advanced composite structures with markedly reduced noise and vibration levels.
Directory of Open Access Journals (Sweden)
Andrea Giovannelli
2017-10-01
Full Text Available The majority of currently published dispersion protocols of carbon nanotubes rely on techniques that are not scalable to an industrial level. This work shows how to obtain polymer nanocomposites with good mechanical characteristics using multi-walled carbon nanotubes epoxy resins obtained by mechanical mixing only. The mechanical dispersion method illustrated in this work is easily scalable to industrial level. The high shearing force due to the complex field of motion produces a good and reproducible carbon nanotube dispersion. We have tested an industrial epoxy matrix with good baseline mechanical characteristics at different carbon nanotube weight loads. ASTM-derived tensile and compressive tests show an increment in both Young’s modulus and compressive strength compared with the pristine resin from a starting low wt %. Comparative vibration tests show improvement in the damping capacity. The new carbon nanotube enhanced epoxy resin has superior mechanical proprieties compared to the market average competitor, and is among the top products in the bi-components epoxy resins market. The new dispersion method shows significant potential for the industrial use of CNTs in epoxy matrices.
Giovannelli, Andrea; Di Maio, Dario; Scarpa, Fabrizio
2017-10-24
The majority of currently published dispersion protocols of carbon nanotubes rely on techniques that are not scalable to an industrial level. This work shows how to obtain polymer nanocomposites with good mechanical characteristics using multi-walled carbon nanotubes epoxy resins obtained by mechanical mixing only. The mechanical dispersion method illustrated in this work is easily scalable to industrial level. The high shearing force due to the complex field of motion produces a good and reproducible carbon nanotube dispersion. We have tested an industrial epoxy matrix with good baseline mechanical characteristics at different carbon nanotube weight loads. ASTM-derived tensile and compressive tests show an increment in both Young's modulus and compressive strength compared with the pristine resin from a starting low wt %. Comparative vibration tests show improvement in the damping capacity. The new carbon nanotube enhanced epoxy resin has superior mechanical proprieties compared to the market average competitor, and is among the top products in the bi-components epoxy resins market. The new dispersion method shows significant potential for the industrial use of CNTs in epoxy matrices.
Miller, G.; Heimann, Paula J.; Scheiman, Daniel A.; Duffy, Kirsten P.; Johnston, J. Chris; Roberts, Gary D.
2013-01-01
Vibration mitigation in composite structures has been demonstrated through widely varying methods which include both active and passive damping. Recently, nanomaterials have been investigated as a viable approach to composite vibration damping due to the large surface available to generate energy dissipation through friction. This work evaluates the influence of dispersed nanoparticles on the damping ratio of an epoxy matrix. Limited benefit was observed through dispersion methods, however nanoparticle application as a coating resulting in up to a three-fold increase in damping.
International Nuclear Information System (INIS)
Mahajan, Sonam; Aggarwal, Neha; ManMohan; Bhattacherjee, Aranya B
2013-01-01
We present a detailed study to show the possibility of approaching the quantum ground state of a hybrid optomechanical quantum device formed by a Bose–Einstein condensate (BEC) confined inside a high-finesse optical cavity with an oscillatory end mirror. Cooling is achieved using two experimentally realizable schemes: back-action cooling and cold damping quantum feedback cooling. In both the schemes, we found that increasing the two-body atom–atom interaction brings the mechanical oscillator to its quantum ground state. It has been observed that back-action cooling is more effective in the good cavity limit, while the cold damping cooling scheme is more relevant in the bad cavity limit. It is also shown that in the cold damping scheme, the device is more efficient in the presence of a BEC than in the absence of a BEC. (paper)
International Nuclear Information System (INIS)
Ware, A.G.; Arendts, J.G.
1984-01-01
A program has been developed to assess the available piping damping data, to generate additional data and conduct seperate effects tests, and to establish a plan for reporting and storing future test results into a data bank. This effort is providing some of the basis for developing higher allowable damping values for piping seismic analyses, which will potentially permit removal of a considerable number of piping supports, particularly snubbers. This in turn will lead to more flexible piping systems which will be less susceptible to thermal cracking, will be easier to maintain and inspect, as well as less costly
Driving and damping mechanisms in hybrid pressure-gravity modes pulsators
Energy Technology Data Exchange (ETDEWEB)
Dupret, M A [Observatoire de Paris, LESIA, CNRS UMR 8109, 5 place J. Janssen, 92195 Meudon (France); Miglio, A; Montalban, J; Noels, A [Institut d' Astrophysique et Geophysique, Universite de Liege (Belgium); Grigahcene, A [CRAAG - Algiers Observatory BP 63 Bouzareah 16340, Algiers (Algeria)], E-mail: MA.dupret@obspm.fr
2008-10-15
We study the energetic aspects of hybrid pressure-gravity modes pulsations. The case of hybrid {beta} Cephei-SPB pulsators is considered with special attention. In addition to the already known sensitivity of the driving mechanism to the heavy elements mixture (mainly the iron abundance), we show that the characteristics of the propagation and evanescent regions play also a major role, determining the extension of the stable gap in the frequency domain between the unstable low order pressure and high order gravity modes. Finally, we consider the case of hybrid {delta} Sct-{gamma} Dor pulsators.
Method for determining damping properties of materials using a suspended mechanical oscillator
Biscans, S.; Gras, S.; Evans, M.; Fritschel, P.; Pezerat, C.; Picart, P.
2018-06-01
We present a new approach for characterizing the loss factor of materials, using a suspended mechanical oscillator. Compared to more standard techniques, this method offers freedom in terms of the size and shape of the tested samples. Using a finite element model and the vibration measurements, the loss factor is deduced from the oscillator's ring-down. In this way the loss factor can be estimated independently for shear and compression deformation of the sample over a range of frequencies. As a proof of concept, we present measurements for EPO-TEK 353ND epoxy samples.
Canuto, Claudio
2014-01-01
Il presente testo intende essere di supporto ad un secondo insegnamento di Analisi Matematica in quei corsi di studio (quali ad esempio Ingegneria, Informatica, Fisica) in cui lo strumento matematico parte significativa della formazione dell'allievo. I concetti e i metodi fondamentali del calcolo differenziale ed integrale in più variabili, le serie di funzioni e le equazioni differenziali ordinarie sono presentati con l'obiettivo primario di addestrare lo studente ad un loro uso operativo, ma critico. L'impostazione didattica dell'opera ricalca quella usata nel testo parallelo di Analisi Matematica I. La modalità di presentazione degli argomenti ne permette un uso flessibile e modulare. Lo stile adottato privilegia la chiarezza e la linearità dell'esposizione. Il testo organizzato su due livelli di lettura. Uno, più essenziale, permette allo studente di cogliere i concetti indispensabili della materia, di familiarizzarsi con le relative tecniche di calcolo e di trovare le giustificazioni dei principali r...
Wu, Ching-Zong; Chen, Shih-Chung; Shih, Yung-Hsun; Hung, Jing-Ming; Lin, Chia-Cheng; Lin, Li-Hsiang; Ou, Keng-Liang
2011-10-01
This research investigated the high-temperature microstructure, mechanical properties, and damping behavior of Fe-9 Al-30 Mn-1C-5 Co (wt.%) alloy by means of electron microscopy, experimental model analysis, and hardness and tensile testing. Subsequent microstructural transformation occurred when the alloy under consideration was subjected to heat treatment in the temperature range of 1000-1150 °C: γ → (γ+κ). The κ-phase carbides had an ordered L'1(2)-type structure with lattice parameter a = 0.385 nm. The maximum yield strength (σ(y)), hardness, elongation, and damping coefficient of this alloy are 645 MPa, Hv 292, ~54%, and 178.5 × 10(-4), respectively. These features could be useful in further understanding the relationship between the biocompatibility and the wear and corrosion resistance of the alloy, so as to allow the development of a promising biomedical material. Copyright © 2011 Elsevier Ltd. All rights reserved.
Tambasco, Claudia; Barranco Garcia, Javier; Boccardi, Andrea; Buffat, Xavier; Bruce, Roderik; Gasior, Marek; Hostettler, Michi; Lefevre, Thibaut; Louro Alves, Diogo Miguel; Metral, Elias; Persson, Tobias Hakan Bjorn; Pieloni, Tatiana; Pojer, Mirko; Salvachua Ferrando, Belen Maria; Solfaroli Camillocci, Matteo; CERN. Geneva. ATS Department
2018-01-01
Beam Transfer Function (BTF) measurements are direct measurement of the stability diagrams that deﬁne the stability threshold of coherent beam instabilities driven by the impedance. At the LHC, some coherent instabilities at ﬂat top energy are still not fully understood and the BTF measurements provide a method to experimentally probe the Landau damping of the proton beams. The BTF response is sensitive to the particle distribution changes and contain information about the transverse tune spread in the beams. The BTF system has been installed in the LHC in the 2015 in order to investigate the Landau damping at different stages of the operational cycle, machine conﬁgurations (different octupole currents, crossing angles, tunes etc...) and in presence of beam-beam excited resonances that may provoke diffusion mechanisms with a consequence change of Landau damping. Past MDs showed some difﬁculties for the reconstruction of the stability diagram from BTF measurements and several improvements on the BTF sy...
International Nuclear Information System (INIS)
Bullock, J.C.; Kelley, B.E.
1977-01-01
A valve for damping out flow surges in a vacuum system is described. The surge-damping mechanism consists of a slotted, spring-loaded disk adjacent to the valve's vacuum port (the flow passage to the vacuum roughing pump). Under flow surge conditions, the differential pressure forces the disk into a sealing engagement with the vacuum port, thereby restricting the gas flow path to narrow slots in the disk's periphery. The increased flow damps out the flow surge. When pressure is equalized on both sides of the valve, the spring load moves the disk away from the port to restore full flow conductance through the valve
Development of new damping devices for piping
International Nuclear Information System (INIS)
Kobayashi, Hiroe
1991-01-01
An increase of the damping ratio is known to be very effective for the seismic design of a piping system. Increasing the damping ratio and reducing the seismic response of the piping system, the following three types of damping devices for piping systems are introduced: (1) visco-elastic damper, (2) elasto-plastic damper and (3) compact dynamic damper. The dynamic characteristics of these damping devices were investigated by the component test and the applicability of them to the piping system was confirmed by the vibration test using a three dimensional piping model. These damping devices are more effective than mechanical snubbers to reduce the vibration of the piping system. (author)
International Nuclear Information System (INIS)
Anderson, M.J.; Barta, D.A.; Lindquist, M.R.; Renkey, E.J.; Ryan, J.A.
1983-06-01
LMFBR pipe systems typically utilize a thicker insulation package than that used on water plant pipe systems. They are supported with special insulated pipe clamps. Mechanical snubbers are employed to resist seismic loads. Recent laboratory testing has indicated that these features provide significantly more damping than presently allowed by Regulatory Guide 1.61 for water plant pipe systems. This paper presents results of additional in-situ vibration tests conducted on FFTF pipe systems. Pipe damping values obtained at various excitation levels are presented. Effects of filtering data to provide damping values at discrete frequencies and the alternate use of a single equivalent modal damping value are discussed. These tests further confirm that damping in typical LMFBR pipe systems is larger than presently used in pipe design. Although some increase in damping occurred with increased excitation amplitude, the effect was not significant. Recommendations are made to use an increased damping value for both the OBE and DBE seismic events in design of LMFBR pipe systems
International Nuclear Information System (INIS)
Shpak, D.E.
1985-01-01
Static stress and temperature are studied experimentally for their separate and joint effect on dissipative properties of VT3-1 and Ehp 718 alloys whose dissipation energy is conditioned by microplastic strains. The results of the study are presented. It is shown that for the materials studied in contrast to the materials with other basic damping mechanisms joint effect of static stresses and temperature is close to a simple summation of the separate effect of these factors without any changes in the character of energy dissipation dependence
Energy Technology Data Exchange (ETDEWEB)
Shpak, D.E.
1985-01-01
Static stress and temperature are studied experimentally for their separate and joint effect on dissipative properties of VT3-1 and Ehp 718 alloys whose dissipation energy is conditioned by microplastic strains. The results of the study are presented. It is shown that for the materials studied in contrast to the materials with other basic damping mechanisms joint effect of static stresses and temperature is close to a simple summation of the separate effect of these factors without any changes in the character of energy dissipation dependence.
Muscle co-contraction modulates damping and joint stability in a three-link bio mechanical limb
Directory of Open Access Journals (Sweden)
Stewart eHeitmann
2012-01-01
Full Text Available Computational models of neuromotor control require forward models of limb movement that can replicate the natural relationships between muscle activation and joint dynamics without the burdens of excessive anatomical detail. We present a model of a three-link biomechanical limb that emphasizes the dynamics of limb movement within a simplified two-dimensional framework. Muscle co-contraction effects were incorporated into the model by flanking each joint with a pair of antagonist muscles that may be activated independently. Muscle co-contraction is known to alter the damping and stiffness of limb joints without altering net joint torque. Idealized muscle actuators were implemented using the Voigt muscle model which incorporates the parallel elasticity of muscle and tendon but omits series elasticity. The natural force-length-velocity relationships of contractile muscle tissue were incorporated into the actuators using ideal mathematical forms. Numerical stability analysis confirmed that co-contraction of these simplified actuators increased damping in the biomechanical limb consistent with observations of human motor control. Dynamic changes in joint stiffness were excluded by the omission of series elasticity. The analysis also revealed the unexpected finding that distinct stable (bistable equilibrium positions can co-exist under identical levels of muscle co-contraction. We map the conditions under which bistability arises and prove analytically that monostability (equifinality is guaranteed when the antagonist muscles are identical. Lastly we verify these analytic findings in the full biomechanical limb model.
Mouhot, Clément
2011-09-01
Going beyond the linearized study has been a longstanding problem in the theory of Landau damping. In this paper we establish exponential Landau damping in analytic regularity. The damping phenomenon is reinterpreted in terms of transfer of regularity between kinetic and spatial variables, rather than exchanges of energy; phase mixing is the driving mechanism. The analysis involves new families of analytic norms, measuring regularity by comparison with solutions of the free transport equation; new functional inequalities; a control of non-linear echoes; sharp "deflection" estimates; and a Newton approximation scheme. Our results hold for any potential no more singular than Coulomb or Newton interaction; the limit cases are included with specific technical effort. As a side result, the stability of homogeneous equilibria of the non-linear Vlasov equation is established under sharp assumptions. We point out the strong analogy with the KAM theory, and discuss physical implications. Finally, we extend these results to some Gevrey (non-analytic) distribution functions. © 2011 Institut Mittag-Leffler.
Parametric Landau damping of space charge modes
Energy Technology Data Exchange (ETDEWEB)
Macridin, Alexandru [Fermilab; Burov, Alexey [Fermilab; Stern, Eric [Fermilab; Amundson, James [Fermilab; Spentzouris, Panagiotis [Fermilab
2016-09-23
Landau damping is the mechanism of plasma and beam stabilization; it arises through energy transfer from collective modes to the incoherent motion of resonant particles. Normally this resonance requires the resonant particle's frequency to match the collective mode frequency. We have identified an important new damping mechanism, parametric Landau damping, which is driven by the modulation of the mode-particle interaction. This opens new possibilities for stability control through manipulation of both particle and mode-particle coupling spectra. We demonstrate the existence of parametric Landau damping in a simulation of transverse coherent modes of bunched accelerator beams with space charge.
Damped nonlinear Schrodinger equation
International Nuclear Information System (INIS)
Nicholson, D.R.; Goldman, M.V.
1976-01-01
High frequency electrostatic plasma oscillations described by the nonlinear Schrodinger equation in the presence of damping, collisional or Landau, are considered. At early times, Landau damping of an initial soliton profile results in a broader, but smaller amplitude soliton, while collisional damping reduces the soliton size everywhere; soliton speeds at early times are unchanged by either kind of damping. For collisional damping, soliton speeds are unchanged for all time
Analisis Statistika dengan SPSS
Mustari, Kahar
2012-01-01
Buku ini membahas tentang berbagai model analisis statistika yang dapat digunakan dalam berbagai bidang penelitian. Pembahasan buku ini dilengkapi pula dengan penerapan analisis statistika yang menggunakan program SPSS versi 20 sehingga memudahkan pembaca untuk menerapkannya. Oleh karena itu, buku ini penting dibaca oleh mahasiswa atau peneliti yang melakukan pengolahan data penelitian.
Damping Measurements of Plasma Modes
Anderegg, F.; Affolter, M.; Driscoll, C. F.
2010-11-01
For azimuthally symmetric plasma modes in a magnesium ion plasma, confined in a 3 Tesla Penning-Malmberg trap with a density of n ˜10^7cm-3, we measure a damping rate of 2s-1plasma column, alters the frequency of the mode from 16 KHz to 192 KHz. The oscillatory fluid displacement is small compared to the wavelength of the mode; in contrast, the fluid velocity, δvf, can be large compared to v. The real part of the frequency satisfies a linear dispersion relation. In long thin plasmas (α> 10) these modes are Trivelpiece-Gould (TG) modes, and for smaller values of α they are Dubin spheroidal modes. However the damping appears to be non-linear; initially large waves have weaker exponential damping, which is not yet understood. Recent theoryootnotetextM.W. Anderson and T.M. O'Neil, Phys. Plasmas 14, 112110 (2007). calculates the damping of TG modes expected from viscosity due to ion-ion collisions; but the measured damping, while having a similar temperature and density dependence, is about 40 times larger than calculated. This discrepancy might be due to an external damping mechanism.
Damping of multispan heat exchanger tubes. Pt. 1: in gases
International Nuclear Information System (INIS)
Pettigrew, M.J.; Goyder, H.G.D.; Qiao, Z.L.; Axisa, F.
1986-07-01
Flow-induced vibration analyses of heat exchanger tubes require the knowledge of damping. This paper treats the question of damping on multispan heat exchanger tubes in air and gases. The different energy dissipation mechanisms that contribute to tube damping are discussed. The available experimental data are reviewed and analysed. We find that the main damping mechanism in gases is friction between tube and tube-supports. Damping is strongly related to tube-support thickness. Damping values are recommended for design purposes. This study is interesting in the nuclear industry for it often uses heat exchangers
Damping in heat exchanger tube bundles. A review
International Nuclear Information System (INIS)
Iqbal, Qamar; Khushnood, Shahab; Ghalban, Ali Roheim El; Sheikh, Nadeem Ahmed; Malik, Muhammad Afzaal; Arastu, Asif
2007-01-01
Damping is a major concern in the design and operation of tube bundles with loosely supported tubes in baffles for process shell and tube heat exchangers and steam generators which are used in nuclear, process and power generation industries. System damping has a strong influence on the amplitude of vibration. Damping depends upon the mechanical properties of the tube material, geometry of intermediate supports and the physical properties of shell-side fluid. Type of tube motion, number of supports, tube frequency, vibration amplitude, tube mass or diameter, side loads, support thickness, higher modes, shell-side temperature etc., affect damping in tube bundles. The importance of damping is further highlighted due to current trend of larger exchangers with increased shell-side velocities in modern units. Various damping mechanisms have been identified (Friction damping, Viscous damping, Squeeze film damping, Support damping. Two-Phase damping, and very recent-Thermal damping), which affect the performance of process exchangers and steam generators with respect to flow induced vibration design, including standard design guidelines. Damping in two-phase flow is very complex and highly void fraction, and flow-regime dependent. The current paper focuses on the various known damping mechanisms subjected to both single and two-phase cross-flow in process heat exchangers and steam generators and formulates the design guidelines for safer design. (author)
Phenomenology of chiral damping in noncentrosymmetric magnets
Akosa, Collins Ashu; Miron, Ioan Mihai; Gaudin, Gilles; Manchon, Aurelien
2016-01-01
A phenomenology of magnetic chiral damping is proposed in the context of magnetic materials lacking inversion symmetry. We show that the magnetic damping tensor acquires a component linear in magnetization gradient in the form of Lifshitz invariants. We propose different microscopic mechanisms that can produce such a damping in ferromagnetic metals, among which local spin pumping in the presence of an anomalous Hall effect and an effective “s-d” Dzyaloshinskii-Moriya antisymmetric exchange. The implication of this chiral damping in terms of domain-wall motion is investigated in the flow and creep regimes.
Phenomenology of chiral damping in noncentrosymmetric magnets
Akosa, Collins Ashu
2016-06-21
A phenomenology of magnetic chiral damping is proposed in the context of magnetic materials lacking inversion symmetry. We show that the magnetic damping tensor acquires a component linear in magnetization gradient in the form of Lifshitz invariants. We propose different microscopic mechanisms that can produce such a damping in ferromagnetic metals, among which local spin pumping in the presence of an anomalous Hall effect and an effective “s-d” Dzyaloshinskii-Moriya antisymmetric exchange. The implication of this chiral damping in terms of domain-wall motion is investigated in the flow and creep regimes.
Directory of Open Access Journals (Sweden)
S. Zhu
1998-01-01
Full Text Available Magnetic damping is one of the important parameters that control the response and stability of maglev systems. An experimental study to measure magnetic damping directly is presented. A plate attached to a permanent magnet levitated on a rotating drum was tested to investigate the effect of various parameters, such as conductivity, gap, excitation frequency, and oscillation amplitude, on magnetic damping. The experimental technique is capable of measuring all of the magnetic damping coefficients, some of which cannot be measured indirectly.
Power oscillation damping controller
DEFF Research Database (Denmark)
2012-01-01
A power oscillation damping controller is provided for a power generation device such as a wind turbine device. The power oscillation damping controller receives an oscillation indicating signal indicative of a power oscillation in an electricity network and provides an oscillation damping control...
Rotational damping motion in nuclei
International Nuclear Information System (INIS)
Egido, J.L.; Faessler, A.
1991-01-01
The recently proposed model to explain the mechanism of the rotational motion damping in nuclei is exactly solved. When compared with the earlier approximative solution, we find significative differences in the low excitation energy limit (i.e. Γ μ 0 ). For the strength functions we find distributions going from the Wigner semicircle through gaussians to Breit-Wigner shapes. (orig.)
Hou, Junfang; jing, Min; Zhang, Weihua; Lu, Yahui; He, Haiwen
2017-12-01
As for the isolation problem of electronic equipments on vehicle, the vibration response characteristics of dry friction damping isolation system under base displacement excitation was analyzed in theory by harmonic balance method, and the displacement response was compared between the isolation systems with dry friction damping and vicious damping separately. The results show that the isolation system with small dry friction damping can’t meet the demands of displacement reduction close to the natural frequency, and it can realize full-frequency vibration isolation by improving dry friction damping when the lock frequency passes beyond the resonance frequency band. The results imply that the damping mechanism of dry friction isolator can’t be described only by dry friction damping, and the composite damping with dry friction and vicious damping is more appropriate.
Active and passive damping based on piezoelectric elements -controllability issues-
Holterman, J.; de Vries, Theodorus J.A.; van Amerongen, J.; Jonker, Jan B.; Jonker, J.B.
2001-01-01
Piezoelectric elements are widely used for damping micro-vibrations in mechanical structures. Active damping can be realised robustly by means of collocated actuator-sensor-pairs, controlled so as to extract vibration energy. Excellent damping performance is possible as long as sufficient
The damped wave equation with unbounded damping
Czech Academy of Sciences Publication Activity Database
Freitas, P.; Siegl, Petr; Tretter, C.
2018-01-01
Roč. 264, č. 12 (2018), s. 7023-7054 ISSN 0022-0396 Institutional support: RVO:61389005 Keywords : damped wave equation * unbounded damping * essential spectrum * quadratic operator funciton with unbounded coefficients * Schrodinger operators with complex potentials Subject RIV: BE - Theoretical Physics OBOR OECD: Atomic, molecular and chemical physics (physics of atoms and molecules including collision, interaction with radiation, magnetic resonances, Mössbauer effect) Impact factor: 1.988, year: 2016
Resonant Electromagnetic Shunt Damping of Flexible Structures
DEFF Research Database (Denmark)
Høgsberg, Jan Becker
2016-01-01
Electromagnetic transducers convert mechanical energy to electrical energy and vice versa. Effective passive vibration damping of flexible structures can therefore be introduced by shunting with an accurately calibrated resonant electrical network thatcontains a capacitor to create the desired...
International Nuclear Information System (INIS)
Macias-Diaz, J.E.; Puri, A.
2007-01-01
In the present Letter, we simulate the propagation of binary signals in semi-infinite, mechanical chains of coupled oscillators harmonically driven at the end, by making use of the recently discovered process of nonlinear supratransmission. Our numerical results-which are based on a brand-new computational technique with energy-invariant properties-show an efficient and reliable transmission of information
DEFF Research Database (Denmark)
Villanueva, Luis Guillermo; Schmid, Silvan
2014-01-01
Silicon nitride (SiN) micro- and nanomechanical resonators have attracted a lot of attention in various research fields due to their exceptionally high quality factors (Qs). Despite their popularity, the origin of the limiting loss mechanisms in these structures has remained controversial. In thi...
Identification of Damping from Structural Vibrations
DEFF Research Database (Denmark)
Bajric, Anela
Reliable predictions of the dynamic loads and the lifetime of structures are inﬂuenced by the limited accuracy concerning the level of structural damping. The mechanisms of damping cannot be derived analytically from ﬁrst principles, and in the design of structures the damping is therefore based...... on experience or estimated from measurements. This thesis consists of an extended summary and three papers which focus on enhanced methods for identiﬁcation of damping from random struc-tural vibrations. The developed methods are validated by stochastic simulations, experimental data and full-scale measurements...... which are representative of the vibrations in small and large-scale structures. The ﬁrst part of the thesis presents an automated procedure which is suitable for estimation of the natural frequencies and the modal damping ratios from random response of structures. The method can be incorporated within...
Damping Estimation of Friction Systems in Random Vibrations
DEFF Research Database (Denmark)
Friis, Tobias; Katsanos, Evangelos; Amador, Sandro
Friction is one of the most efficient and economical mechanisms to reduce vibrations in structural mechanics. However, the estimation of the equivalent linear damping of the friction damped systems in experimental modal analysis and operational modal analysis can be adversely affected by several...... assumptions regarding the definition of the linear damping and the identification methods or may be lacking a meaningful interpretation of the damping. Along these lines, this project focuses on assessing the potential to estimate efficiently the equivalent linear damping of friction systems in random...
Shape memory alloys as damping materials
International Nuclear Information System (INIS)
Humbeeck, J. van
2000-01-01
Shape memory alloys are gaining an increased interest as passive as well as active damping materials. This damping ability when applied in structural elements can lead to a better noise control, improved life time and even better performance of the envisaged tools. By passive damping, it is understood that the material converts a significant part of unwanted mechanical energy into heat. This mechanical energy can be a (resonance) vibration, impact loading or shock waves. This high damping capacity finds its origin in the thermoelastic martensitic phase due to the hysteretic mobility of martensite-variants or different phase interfaces. The damping capacity increases with increasing amplitude of the applied vibration or impact and is almost frequency independent. Special interest exists moreover for damping extreme large displacements by applying the mechanical hysteresis performed during pseudoelastic loading. This aspect is nowadays very strongly studied as a tool for protecting buildings against earthquakes in seismic active regions. Active damping can be obtained in hybrid composites by controlling the recovery stresses or strains of embedded shape memory alloy wires. This controls the internal energy fo a structure which allows controlled modal modification and tuning of the dynamical properties of structural elements. But also impact damage, acoustic radiation, dynamic shape control can be actively controlled. As a consequence improved fatigue-resistance, better performance and a longer lifetime of the structural elements can be obtained. (orig.)
Labonnote, Nathalie
2012-01-01
Key point to development of environmentally friendly timber structures, appropriate to urban ways of living, is the development of high-rise timber buildings. Comfort properties are nowadays one of the main limitations to tall timber buildings, and an enhanced knowledge on damping phenomena is therefore required, as well as improved prediction models for damping. The aim of this work has consequently been to estimate various damping quantities in timber structures. In particular, models h...
The damped wave equation with unbounded damping
Freitas, Pedro; Siegl, Petr; Tretter, Christiane
2018-06-01
We analyze new phenomena arising in linear damped wave equations on unbounded domains when the damping is allowed to become unbounded at infinity. We prove the generation of a contraction semigroup, study the relation between the spectra of the semigroup generator and the associated quadratic operator function, the convergence of non-real eigenvalues in the asymptotic regime of diverging damping on a subdomain, and we investigate the appearance of essential spectrum on the negative real axis. We further show that the presence of the latter prevents exponential estimates for the semigroup and turns out to be a robust effect that cannot be easily canceled by adding a positive potential. These analytic results are illustrated by examples.
Decoherence and Landau-Damping
Energy Technology Data Exchange (ETDEWEB)
Ng, K.Y.; /Fermilab
2005-12-01
The terminologies, decoherence and Landau damping, are often used concerning the damping of a collective instability. This article revisits the difference and relation between decoherence and Landau damping. A model is given to demonstrate how Landau damping affects the rate of damping coming from decoherence.
Route Flap Damping Made Usable
Pelsser, Cristel; Maennel, Olaf; Mohapatra, Pradosh; Bush, Randy; Patel, Keyur
The Border Gateway Protocol (BGP), the de facto inter-domain routing protocol of the Internet, is known to be noisy. The protocol has two main mechanisms to ameliorate this, MinRouteAdvertisementInterval (MRAI), and Route Flap Damping (RFD). MRAI deals with very short bursts on the order of a few to 30 seconds. RFD deals with longer bursts, minutes to hours. Unfortunately, RFD was found to severely penalize sites for being well-connected because topological richness amplifies the number of update messages exchanged. So most operators have disabled it. Through measurement, this paper explores the avenue of absolutely minimal change to code, and shows that a few RFD algorithmic constants and limits can be trivially modified, with the result being damping a non-trivial amount of long term churn without penalizing well-behaved prefixes' normal convergence process.
Single bunch beam breakup in linacs and BNS damping
International Nuclear Information System (INIS)
Toyomasu, Takanori
1991-12-01
We study a single-bunch beam breakup (BBU) problem by a macro-particle model. We consider both the BBU solution and the Landau damping solution which includes the Balakin-Novokhatsky-Smirnov (BNS) damping. In the BBU solution, we get an analytic solution which includes both the Chao-Richter-Yao solution and the two-particle model solution and which agrees well with simulation. The solution can also be used in a multi-bunch case. In the Landau damping solution, we can be see the mechanism of Landau damping formally and can get some insights into BNS damping. We confirm that a two-particle model criterion for BNS damping is a good one. We expect that the two-particle model criterion is represented by the first order interaction in Landau damping solution of a macro-particle model. (author)
A review of damping of two-phase flows
International Nuclear Information System (INIS)
Hara, Fumio
1993-01-01
Damping of two-phase flows has been recognized as one of the most unknown parameters in analyzing vibrational characteristics of structures subjected to two-phase flows since it seems to be influenced by many physical parameters involved in the physics of dynamic energy dissipation of a vibrating structure, for example, liquid viscosity, surface tension, flow velocity, mass ratio, frequency, void fraction, flow regime and so forth. This paper deals with a review of scientific works done to date on the damping of two phase flows and discussions about what has been clarified and what has not been known to us, or what kinds of research are needed about two-phase flow damping. The emphasis is put on the definition of two-phase fluid damping, damping measurement techniques, damping characteristics in relation to two phase flow configurations, and damping generation mechanisms
Yang, Juan; Liu, Ying; Huang, Jian; Xu, Jinbang; You, Xiumi; Lin, Qiuping; Zhang, Junxin; Dun, Jingjing; Huang, Shan
2017-11-12
To explore the effect difference between acupuncture combined with Chinese medicine of artificial cycle therapy on the basis of western medication and simple western medication for polycystic ovarian syndrome (PCOS) of phlegm damp type with insulin resistance, and to explore its mechanism. Sixty patients were randomly assigned into an observation group and a control group, 30 cases in each group. Patients of the control group began to take letrozole and metformin orally on the third menstrual day. Patients of the observation group were treated with acupuncture combined with Chinese medicine of artificial cycle therapy on the basis of the treatment of the control group. The main acupoints were Guanyuan (CV 4), Qihai (CV 6) and bilateral Zigong (EX-CA 1), Luanchao (Extra), Fenglong (ST 40), Yinlingquan (SP 9), Zusanli (ST 36), Sanyinjiao (SP 6). Dahe (KI 12) was matched in the follicular phase, and warm acupuncture was applied at Guanyuan (CV 4) and Qihai (CV 6); Zhongji (CV 3) and Xuehai (SP 10) were matched in the ovulatory phase, and electroacupuncture were used at Qihai (CV 6) and Zhongji (CV 3), Xuehai (SP 10) and Yinlingquan (SP 9), 2 Hz and continuous wave; The acupoints in the luteal phase were the above main acupoints, at the same time, moxibustion was used at Guanyuan (CV 4) and Qihai (CV 6), the treatment was given once every other day, 30 min a time. There was no treatment in the menstrual phase. Chinese medicine was applied for tonifying kidney and nourishing blood, strengthening spleen and eliminating phlegm. The patients of the two groups were treated for continuous three menstrual cycles. The indexes before and after treatment were detected, including serum microRNA-29 (miR-29) expression, TCM symptom score, insulin (INS), blood-sugar content and homeostasis model assessment-insulin resistance (HOMA-IR) index, the endocrine hormone values of follicle stimulating hormone (FSH), luteinizing hormone (LH), testosterone (T), LH/FSH ratio, prolactin (PRL
DAMPs, ageing, and cancer: The 'DAMP Hypothesis'.
Huang, Jin; Xie, Yangchun; Sun, Xiaofang; Zeh, Herbert J; Kang, Rui; Lotze, Michael T; Tang, Daolin
2015-11-01
Ageing is a complex and multifactorial process characterized by the accumulation of many forms of damage at the molecular, cellular, and tissue level with advancing age. Ageing increases the risk of the onset of chronic inflammation-associated diseases such as cancer, diabetes, stroke, and neurodegenerative disease. In particular, ageing and cancer share some common origins and hallmarks such as genomic instability, epigenetic alteration, aberrant telomeres, inflammation and immune injury, reprogrammed metabolism, and degradation system impairment (including within the ubiquitin-proteasome system and the autophagic machinery). Recent advances indicate that damage-associated molecular pattern molecules (DAMPs) such as high mobility group box 1, histones, S100, and heat shock proteins play location-dependent roles inside and outside the cell. These provide interaction platforms at molecular levels linked to common hallmarks of ageing and cancer. They can act as inducers, sensors, and mediators of stress through individual plasma membrane receptors, intracellular recognition receptors (e.g., advanced glycosylation end product-specific receptors, AIM2-like receptors, RIG-I-like receptors, and NOD1-like receptors, and toll-like receptors), or following endocytic uptake. Thus, the DAMP Hypothesis is novel and complements other theories that explain the features of ageing. DAMPs represent ideal biomarkers of ageing and provide an attractive target for interventions in ageing and age-associated diseases. Copyright © 2014 Elsevier B.V. All rights reserved.
Extended Rayleigh Damping Model
Directory of Open Access Journals (Sweden)
Naohiro Nakamura
2016-07-01
Full Text Available In dynamic analysis, frequency domain analysis can be used if the entire structure is linear. However, time history analysis is generally used if nonlinear elements are present. Rayleigh damping has been widely used in time history response analysis. Many articles have reported the problems associated with this damping and suggested remedies. A basic problem is that the frequency area across which the damping ratio is almost constant is too narrow. If the area could be expanded while incurring only a small increase in computational cost, this would provide an appropriate remedy for this problem. In this study, a novel damping model capable of expanding the constant frequency area by more than five times was proposed based on the study of a causal damping model. This model was constructed by adding two terms to the Rayleigh damping model and can be applied to the linear elements in the time history analysis of a nonlinear structure. The accuracy and efficiency of the model were confirmed using example analyses.
Sheath waves, non collisional dampings
International Nuclear Information System (INIS)
Marec, Jean Lucien Ernest
1974-01-01
When a metallic conductor is inserted into an ionised gas, an area of electron depletion is formed between the conductor and the plasma: the ionic sheath. Moreover, if the conductor is excited by an electric field, this ionic sheath plays an important role with respect to microwave properties. In this research thesis, the author addresses the range of frequencies smaller than the plasma frequency, and reports the study of resonance phenomena. After a presentation of the problem through a bibliographical study, the author recalls general characteristics of sheath wave propagation and of sheath resonances, and discusses the validity of different hypotheses (for example and among others, electrostatic approximations, cold plasma). Then, the author more particularly addresses theoretical problems related to non collisional dampings: brief bibliographical study, detailed presentation and description of the theoretical model, damping calculation methods. The author then justifies the design and performance of an experiment, indicates measurement methods used to determine plasma characteristics as well as other magnitudes which allow the description of mechanisms of propagation and damping of sheath waves. Experimental results are finally presented with respect to various parameters. The author discusses to which extent the chosen theoretical model is satisfying [fr
The DAMPE silicon tungsten tracker
Gallo, Valentina; Asfandiyarov, R; Azzarello, P; Bernardini, P; Bertucci, B; Bolognini, A; Cadoux, F; Caprai, M; Domenjoz, M; Dong, Y; Duranti, M; Fan, R; Franco, M; Fusco, P; Gargano, F; Gong, K; Guo, D; Husi, C; Ionica, M; Lacalamita, N; Loparco, F; Marsella, G; Mazziotta, M N; Mongelli, M; Nardinocchi, A; Nicola, L; Pelleriti, G; Peng, W; Pohl, M; Postolache, V; Qiao, R; Surdo, A; Tykhonov, A; Vitillo, S; Wang, H; Weber, M; Wu, D; Wu, X; Zhang, F; De Mitri, I; La Marra, D
2017-01-01
The DArk Matter Particle Explorer (DAMPE) satellite has been successfully launched on the 17th December 2015. It is a powerful space detector designed for the identification of possible Dark Matter signatures thanks to its capability to detect electrons and photons with an unprecedented energy resolution in an energy range going from few GeV up to 10 TeV. Moreover, the DAMPE satellite will contribute to a better understanding of the propagation mechanisms of high energy cosmic rays measuring the nuclei flux up to 100 TeV. DAMPE is composed of four sub-detectors: a plastic strip scintillator, a silicon-tungsten tracker-converter (STK), a BGO imaging calorimeter and a neutron detector. The STK is made of twelve layers of single-sided AC-coupled silicon micro-strip detectors for a total silicon area of about 7 $m^2$ . To promote the conversion of incident photons into electron-positron pairs, tungsten foils are inserted into the supporting structure. In this document, a detailed description of the STK constructi...
Damping Analysis of Cylindrical Composite Structures with Enhanced Viscoelastic Properties
Kliem, Mathias; Høgsberg, Jan; Vanwalleghem, Joachim; Filippatos, Angelos; Hoschützky, Stefan; Fotsing, Edith-Roland; Berggreen, Christian
2018-04-01
Constrained layer damping treatments are widely used in mechanical structures to damp acoustic noise and mechanical vibrations. A viscoelastic layer is thereby applied to a structure and covered by a stiff constraining layer. When the structure vibrates in a bending mode, the viscoelastic layer is forced to deform in shear mode. Thus, the vibration energy is dissipated as low grade frictional heat. This paper documents the efficiency of passive constrained layer damping treatments for low frequency vibrations of cylindrical composite specimens made of glass fibre-reinforced plastics. Different cross section geometries with shear webs have been investigated in order to study a beneficial effect on the damping characteristics of the cylinder. The viscoelastic damping layers are placed at different locations within the composite cylinder e.g. circumferential and along the neutral plane to evaluate the location-dependent efficiency of constrained layer damping treatments. The results of the study provide a thorough understanding of constrained layer damping treatments and an improved damping design of the cylindrical composite structure. The highest damping is achieved when placing the damping layer in the neutral plane perpendicular to the bending load. The results are based on free decay tests of the composite structure.
Electromagnetic damping of neutron star oscillations
International Nuclear Information System (INIS)
McDermott, P.N.; Savedoff, M.P.; Van Horn, H.M.; Zweibel, E.G.; Hansen, C.J.
1984-01-01
Nonradial pulsations of a neutron star with a strong dipole magnetic field cause emission of electromagnetic radiation. Here we compute the power radiated to vacuum by neutron star g-mode pulsations and by torsional oscillations of the neutron star crust. For the low-order quadrupole fluid g-modes we have considered, we find electromagnetic damping to be considerably more effective than gravitational radiation. For example, a 0.5 M/sub sun/ neutron star with a core temperature approx.10 7 K has a g 1 -mode period of 371 ms; for this mode were find the electromagnetic damping time to be tau/sub FM/approx.0.3 s, assuming the surface magnetic field strength of the neutron star to be B 0 approx.10 12 gauss. This is considerably less than the corresponding gravitational radiation time tau/sub GR/approx.3 x 10 17 yr. For dipole g-mode oscillations, there is no gravitational radiation, but electromagnetic damping and ohmic dissipation are efficient damping mechanisms. For dipole torsional oscillations, we find that electromagnetic damping again dominates, with tau/sub EM/approx.5 yr. Among the cases we have studied, quadrupole torsional oscillations appear to be dominated by gravitational radiation damping, with tau/sub GR/approx.10 4 yr, as compared with tau/sub EM/approx.2 x 10 7 yr
Non-Linear Slosh Damping Model Development and Validation
Yang, H. Q.; West, Jeff
2015-01-01
Propellant tank slosh dynamics are typically represented by a mechanical model of spring mass damper. This mechanical model is then included in the equation of motion of the entire vehicle for Guidance, Navigation and Control (GN&C) analysis. For a partially-filled smooth wall propellant tank, the critical damping based on classical empirical correlation is as low as 0.05%. Due to this low value of damping, propellant slosh is potential sources of disturbance critical to the stability of launch and space vehicles. It is postulated that the commonly quoted slosh damping is valid only under the linear regime where the slosh amplitude is small. With the increase of slosh amplitude, the critical damping value should also increase. If this nonlinearity can be verified and validated, the slosh stability margin can be significantly improved, and the level of conservatism maintained in the GN&C analysis can be lessened. The purpose of this study is to explore and to quantify the dependence of slosh damping with slosh amplitude. Accurately predicting the extremely low damping value of a smooth wall tank is very challenging for any Computational Fluid Dynamics (CFD) tool. One must resolve thin boundary layers near the wall and limit numerical damping to minimum. This computational study demonstrates that with proper grid resolution, CFD can indeed accurately predict the low damping physics from smooth walls under the linear regime. Comparisons of extracted damping values with experimental data for different tank sizes show very good agreements. Numerical simulations confirm that slosh damping is indeed a function of slosh amplitude. When slosh amplitude is low, the damping ratio is essentially constant, which is consistent with the empirical correlation. Once the amplitude reaches a critical value, the damping ratio becomes a linearly increasing function of the slosh amplitude. A follow-on experiment validated the developed nonlinear damping relationship. This discovery can
International Nuclear Information System (INIS)
Ware, A.G.
1986-01-01
The Idaho National Engineering Laboratory (INEL) is conducting a research program to assist the United States Nuclear Regulatory Commission (USNRC) in determining best-estimate damping values for use in the dynamic analysis of nuclear power plant piping systems. This paper describes four tasks in the program that were undertaken in FY-86. In the first task, tests were conducted on a 5-in. INEL laboratory piping system and data were analyzed from a 6-in. laboratory system at the ANCO Engineers facility to investigate the parameters influencing damping in the seismic frequency range. Further tests were conducted on 3- and 5-in. INEL laboratory piping systems as the second task to determine damping values representative of vibrations in the 33 to 100 Hz range, typical of hydrodynamic transients. In the third task a statistical evaluation of the available damping data was conduted to determine probability distributions suitable for use in probabilistic risk assessments (PRAs), and the final task evaluated damping data at high strain levels
Magnetic damping phenomena in ferromagnetic thin-films and multilayers
Azzawi, S.; Hindmarch, A. T.; Atkinson, D.
2017-11-01
Damped ferromagnetic precession is an important mechanism underpinning the magnetisation processes in ferromagnetic materials. In thin-film ferromagnets and ferromagnetic/non-magnetic multilayers, the role of precession and damping can be critical for spintronic device functionality and as a consequence there has been significant research activity. This paper presents a review of damping in ferromagnetic thin-films and multilayers and collates the results of many experimental studies to present a coherent synthesis of the field. The terms that are used to define damping are discussed with the aim of providing consistent definitions for damping phenomena. A description of the theoretical basis of damping is presented from early developments to the latest discussions of damping in ferromagnetic thin-films and multilayers. An overview of the time and frequency domain methods used to study precessional magnetisation behaviour and damping in thin-films and multilayers is also presented. Finally, a review of the experimental observations of magnetic damping in ferromagnetic thin-films and multilayers is presented with the most recent explanations. This brings together the results from many studies and includes the effects of ferromagnetic film thickness, the effects of composition on damping in thin-film ferromagnetic alloys, the influence of non-magnetic dopants in ferromagnetic films and the effects of combining thin-film ferromagnets with various non-magnetic layers in multilayered configurations.
International Nuclear Information System (INIS)
Turner, Sam
2011-01-01
The phenomenon of process damping as a stabilising effect in milling has been encountered by machinists since milling and turning began. It is of great importance when milling aerospace alloys where maximum surface speed is limited by excessive tool wear and high speed stability lobes cannot be attained. Much of the established research into regenerative chatter and chatter avoidance has focussed on stability lobe theory with different analytical and time domain models developed to expand on the theory first developed by Trusty and Tobias. Process damping is a stabilising effect that occurs when the surface speed is low relative to the dominant natural frequency of the system and has been less successfully modelled and understood. Process damping is believed to be influenced by the interference of the relief face of the cutting tool with the waveform traced on the cut surface, with material properties and the relief geometry of the tool believed to be key factors governing performance. This study combines experimental trials with Finite Element (FE) simulation in an attempt to identify and understand the key factors influencing process damping performance in titanium milling. Rake angle, relief angle and chip thickness are the variables considered experimentally with the FE study looking at average radial and tangential forces and surface compressive stress. For the experimental study a technique is developed to identify the critical process damping wavelength as a means of measuring process damping performance. For the range of parameters studied, chip thickness is found to be the dominant factor with maximum stable parameters increased by a factor of 17 in the best case. Within the range studied, relief angle was found to have a lesser effect than expected whilst rake angle had an influence.
Lázaro, Mario
2018-01-01
In this paper, nonviscous, nonproportional, vibrating structures are considered. Nonviscously damped systems are characterized by dissipative mechanisms which depend on the history of the response velocities via hereditary kernel functions. Solutions of the free motion equation lead to a nonlinear eigenvalue problem involving mass, stiffness and damping matrices. Viscoelasticity leads to a frequency dependence of this latter. In this work, a novel closed-form expression to estimate complex eigenvalues is derived. The key point is to consider the damping model as perturbed by a continuous fictitious parameter. Assuming then the eigensolutions as function of this parameter, the computation of the eigenvalues sensitivity leads to an ordinary differential equation, from whose solution arises the proposed analytical formula. The resulting expression explicitly depends on the viscoelasticity (frequency derivatives of the damping function), the nonproportionality (influence of the modal damping matrix off-diagonal terms). Eigenvectors are obtained using existing methods requiring only the corresponding eigenvalue. The method is validated using a numerical example which compares proposed with exact ones and with those determined from the linear first order approximation in terms of the damping matrix. Frequency response functions are also plotted showing that the proposed approach is valid even for moderately or highly damped systems.
Enhancing the Damping Properties of Viscoelastic Composites by Topology Optimization
DEFF Research Database (Denmark)
Andreasen, Casper Schousboe; Andreassen, Erik; Sigmund, Ole
Vibrations, if undamped, might be annoying or even dangerous. Most often some kind of damping mechanism is applied in order to limit the vibration level. Vibration insulators, for instance of rubber material, have favorable damping characteristics but lack the structural stiffness often needed...... in engineering structures. Thus, materials or composites with high stiffness and high damping are of great interest to the industry. The inherent compromise between high stiffness and high damping in viscoelastic materials has been treated theoretically [2, 3] and experimentally [1]. It has been shown that high...
Design, Fabrication, and Properties of High Damping Metal Matrix Composites—A Review
Directory of Open Access Journals (Sweden)
Qianfeng Fang
2009-08-01
Full Text Available Nowadays it is commonly considered that high damping materials which have both the good mechanical properties as structural materials and the high damping capacity for vibration damping are the most direct vibration damping solution. In metals and alloys however, exhibiting simultaneously high damping capacity and good mechanical properties has been noted to be normally incompatible because the microscopic mechanisms responsible for internal friction (namely damping capacity are dependent upon the parameters that control mechanical strength. To achieve a compromise, one of the most important methods is to develop two-phase composites, in which each phase plays a specific role: damping or mechanical strength. In this review, we have summarized the development of the design concept of high damping composite materials and the investigation of their fabrication and properties, including mechanical and damping properties, and suggested a new design concept of high damping composite materials where the hard ceramic additives exhibit high damping capacity at room temperature owing to the stress-induced reorientation of high density point defects in the ceramic phases and the high damping capacity of the composite comes mainly from the ceramic phases.
Enhancing the damping of wind turbine rotor blades, the DAMPBLADE project
DEFF Research Database (Denmark)
Chaviaropoulos, P.K.; Politis, E.S.; Lekou, D.J.
2006-01-01
A research programme enabling the development of damped wind turbine blades, having the acronym DAMPBLADE, has been supported by the EC under its 5th Framework Programme. In DAMPBLADE the following unique composite damping mechanisms were exploited aiming to increase the structural damping......: tailoring of laminate damping anisotropy, damping layers and damped polymer matrices. Additional objectives of the project were the development of the missing critical analytical technologies enabling the explicit modelling of composite structural damping and a novel ‘composite blade design capacity......’ enabling the direct prediction of aeroelastic stability and fatigue life; the development and characterization of damped composite materials; and the evaluation of new technology via the design and fabrication of damped prototype blades and their full-scale laboratory testing. After 4 years of work a 19 m...
Rahimi, Z.; Rashahmadi, S.
2017-11-01
The thermo-elastic damping is a dominant source of internal damping in micro-electromechanical systems (MEMS) and nano-electromechanical systems (NEMS). The internal damping cannot neither be controlled nor minimized unless either mechanical or geometrical properties are changed. Therefore, a novel FGMNEM system with a controllable thermo-elastic damping of axial vibration based on Eringen nonlocal theory is considered. The effects of different parameter like the gradient index, nonlocal parameter, length of nanobeam and ambient temperature on the thermo-elastic damping quality factor are presented. It is shown that the thermo-elastic damping can be controlled by changing different parameter.
Fast damping in mismatched high intensity beam transportation
Directory of Open Access Journals (Sweden)
V. Variale
2001-08-01
Full Text Available A very fast damping of beam envelope oscillation amplitudes was recently observed in simulations of high intensity beam transport, through periodic FODO cells, in mismatched conditions [V. Variale, Nuovo Cimento Soc. Ital. Fis. 112A, 1571–1582 (1999 and T. Clauser et al., in Proceedings of the Particle Accelerator Conference, New York, 1999 (IEEE, Piscataway, NJ, 1999, p. 1779]. A Landau damping mechanism was proposed at the origin of observed effect. In this paper, to further investigate the source of this fast damping, extensive simulations have been carried out. The results presented here support the interpretation of the mechanism at the origin of the fast damping as a Landau damping effect.
Damping of Coherent oscillations
Vos, L
1996-01-01
Damping of coherent oscillations by feedback is straightforward in principle. It has been a vital ingredient for the safe operation of accelerators since a long time. The increasing dimensions and beam intensities of the new generation of hadron colliders impose unprecedented demands on the performance of future systems. The arguments leading to the specification of a transverse feedback system for the CERN SPS in its role as LHC injector and the LHC collider itself are developped to illustrate this. The preservation of the transverse emittance is the guiding principle during this exercise keeping in mind the hostile environment which comprises: transverse impedance bent on developping coupled bunch instabilities, injection errors, unwanted transverse excitation, unavoidable tune spreads and noise in the damping loop.
Jowett, John M; Zimmermann, Frank; Owen, H
2001-01-01
The Compact Linear Colider (CLIC) is designed to operate at 3 TeV centre-of-mass energy with a total luminosity of 10^35 cm^-2 s^-1. The overall system design leads to extremely demanding requirements on the bunch trains injected into the main libac at frequency of 100 Hz. In particular, the emittances of the intense bunches have to be about an order of magnitude smaller than presently achieved. We describe our approach to finding a damping ring design capable of meeting these requirements. Besides lattice design, emittance and damping rate considerations, a number of scattering and instability effects have to be incorporated into the optimisation of parameters. Among these, intra-bem scattering and the electron cloud effect are two of the most significant.
Dislocation damping during irradiation
International Nuclear Information System (INIS)
Burdett, C.F.; Rahmatalla, H.
1977-01-01
The results of Simpson et al (Simpson, H.M., Sosin, A., Johnston, D.F., Phys.Rev. B, 5:1393 (1972)) on the damping produced during electron irradiation of copper are re-examined and it is shown that they can be explained in terms of the model of Granato and Lucke (Granato, A., Lucke, K., J.Appl.Phys., 27:583,789 (1958)). (author)
International Nuclear Information System (INIS)
Shibata, H.; Ito, A.; Tanaka, K.; Niino, T.; Gotoh, N.
1981-01-01
Generally, damping phenomena of structures and equipments is caused by very complex energy dissipation. Especially, as piping systems are composed of many components, it is very difficult to evaluate damping characteristics of its system theoretically. On the other hand, the damping value for aseismic design of nuclear power plants is very important design factor to decide seismic response loads of structures, equipments and piping systems. The very extensive studies titled SDREP (Seismic Damping Ratio Evaluation Program) were performed to establish proper damping values for seismic design of piping as a joint work among a university, electric companies and plant makers. In SDREP, various systematic vibration tests were conducted to investigate factors which may contribute to damping characteristics of piping systems and to supplement the data of the pre-operating tests. This study is related to the component damping characteristics tests of that program. The object of this study is to clarify damping characteristics and mechanism of hanger supports used in piping systems, and to establish the evaluation technique of dispersing energy at hanger support points and its effect to the total damping ability of piping system. (orig./WL)
Preliminary Study on the Damping Effect of a Lateral Damping Buffer under a Debris Flow Load
Directory of Open Access Journals (Sweden)
Zheng Lu
2017-02-01
Full Text Available Simulating the impact of debris flows on structures and exploring the feasibility of applying energy dissipation devices or shock isolators to reduce the damage caused by debris flows can make great contribution to the design of disaster prevention structures. In this paper, we propose a new type of device, a lateral damping buffer, to reduce the vulnerability of building structures to debris flows. This lateral damping buffer has two mechanisms of damage mitigation: when debris flows impact on a building, it acts as a buffer, and when the structure vibrates due to the impact, it acts as a shock absorber, which can reduce the maximum acceleration response and subsequent vibration respectively. To study the effectiveness of such a lateral damping buffer, an impact test is conducted, which mainly involves a lateral damping buffer attached to a two-degree-of-freedom structure under a simulated debris flow load. To enable the numerical study, the equation of motion of the structure along with the lateral damping buffer is derived. A subsequent parametric study is performed to optimize the lateral damping buffer. Finally, a practical design procedure is also provided.
Directory of Open Access Journals (Sweden)
Tai-Hong Cheng
2015-01-01
Full Text Available Composite materials are increasingly used in wind blade because of their superior mechanical properties such as high strength-to-weight and stiffness-to-weight ratio. This paper presents vibration and damping analysis of fiberreinforced composite wind turbine blade with viscoelastic damping treatment. The finite element method based on full layerwise displacement theory was employed to analyze the damping, natural frequency, and modal loss factor of composite shell structure. The lamination angle was considered in mathematical modeling. The curved geometry, transverse shear, and normal strains were exactly considered in present layerwise shell model, which can depict the zig-zag in-plane and out-of-plane displacements. The frequency response functions of curved composite shell structure and wind blade were calculated. The results show that the damping ratio of viscoelastic layer is found to be very sensitive to determination of magnitude of composite structures. The frequency response functions with variety of thickness of damping layer were investigated. Moreover, the natural frequency, modal loss factor, and mode shapes of composite fiber reinforced wind blade with viscoelastic damping control were calculated.
Chiral damping of magnetic domain walls
Jué , Emilie; Safeer, C. K.; Drouard, Marc; Lopez, Alexandre; Balint, Paul; Buda-Prejbeanu, Liliana; Boulle, Olivier; Auffret, Stephane; Schuhl, Alain; Manchon, Aurelien; Miron, Ioan Mihai; Gaudin, Gilles
2015-01-01
Structural symmetry breaking in magnetic materials is responsible for the existence of multiferroics1, current-induced spin–orbit torques2, 3, 4, 5, 6, 7 and some topological magnetic structures8, 9, 10, 11, 12. In this Letter we report that the structural inversion asymmetry (SIA) gives rise to a chiral damping mechanism, which is evidenced by measuring the field-driven domain-wall (DW) motion in perpendicularly magnetized asymmetric Pt/Co/Pt trilayers. The DW dynamics associated with the chiral damping and those with Dzyaloshinskii–Moriya interaction (DMI) exhibit identical spatial symmetry13, 14, 15, 16, 17, 18, 19. However, both scenarios are differentiated by their time reversal properties: whereas DMI is a conservative effect that can be modelled by an effective field, the chiral damping is purely dissipative and has no influence on the equilibrium magnetic texture. When the DW motion is modulated by an in-plane magnetic field, it reveals the structure of the internal fields experienced by the DWs, allowing one to distinguish the physical mechanism. The chiral damping enriches the spectrum of physical phenomena engendered by the SIA, and is essential for conceiving DW and skyrmion devices owing to its coexistence with DMI (ref. 20).
Chiral damping of magnetic domain walls
Jué, Emilie
2015-12-21
Structural symmetry breaking in magnetic materials is responsible for the existence of multiferroics1, current-induced spin–orbit torques2, 3, 4, 5, 6, 7 and some topological magnetic structures8, 9, 10, 11, 12. In this Letter we report that the structural inversion asymmetry (SIA) gives rise to a chiral damping mechanism, which is evidenced by measuring the field-driven domain-wall (DW) motion in perpendicularly magnetized asymmetric Pt/Co/Pt trilayers. The DW dynamics associated with the chiral damping and those with Dzyaloshinskii–Moriya interaction (DMI) exhibit identical spatial symmetry13, 14, 15, 16, 17, 18, 19. However, both scenarios are differentiated by their time reversal properties: whereas DMI is a conservative effect that can be modelled by an effective field, the chiral damping is purely dissipative and has no influence on the equilibrium magnetic texture. When the DW motion is modulated by an in-plane magnetic field, it reveals the structure of the internal fields experienced by the DWs, allowing one to distinguish the physical mechanism. The chiral damping enriches the spectrum of physical phenomena engendered by the SIA, and is essential for conceiving DW and skyrmion devices owing to its coexistence with DMI (ref. 20).
Self-sustained solitons in systems with nonlinear damping
International Nuclear Information System (INIS)
Gonzalez, J.A.
1993-05-01
The existence and stability of kinks in systems with nonlinear damping are investigated. We discuss the mechanism of a bifurcation after which the kink becomes a non-stationary state. (author). 9 refs
Damping measurements in flowing water
Coutu, A.; Seeley, C.; Monette, C.; Nennemann, B.; Marmont, H.
2012-11-01
Fluid-structure interaction (FSI), in the form of mass loading and damping, governs the dynamic response of water turbines, such as Francis turbines. Water added mass and damping are both critical quantities in evaluating the dynamic response of the turbine component. Although the effect of fluid added mass is well documented, fluid damping, a critical quantity to limit vibration amplitudes during service, and therefore to help avoiding possible failure of the turbines, has received much less attention in the literature. This paper presents an experimental investigation of damping due to FSI. The experimental setup, designed to create dynamic characteristics similar to the ones of Francis turbine blades is discussed, together with the experimental protocol and examples of measurements obtained. The paper concludes with the calculated damping values and a discussion on the impact of the observed damping behaviour on the response of hydraulic turbine blades to FSI.
Damping measurements in flowing water
International Nuclear Information System (INIS)
Coutu, A; Monette, C; Nennemann, B; Marmont, H; Seeley, C
2012-01-01
Fluid-structure interaction (FSI), in the form of mass loading and damping, governs the dynamic response of water turbines, such as Francis turbines. Water added mass and damping are both critical quantities in evaluating the dynamic response of the turbine component. Although the effect of fluid added mass is well documented, fluid damping, a critical quantity to limit vibration amplitudes during service, and therefore to help avoiding possible failure of the turbines, has received much less attention in the literature. This paper presents an experimental investigation of damping due to FSI. The experimental setup, designed to create dynamic characteristics similar to the ones of Francis turbine blades is discussed, together with the experimental protocol and examples of measurements obtained. The paper concludes with the calculated damping values and a discussion on the impact of the observed damping behaviour on the response of hydraulic turbine blades to FSI.
High damping Fe-Mn martensitic alloys for engineering applications
International Nuclear Information System (INIS)
Baik, S.-H.
2000-01-01
Conventional methods for reducing vibration in engineering designs (i.e. by stiffening or detuning) may be undesirable or inadequate in conditions where size or weight must be minimized or where complex vibration spectra exist. Alloys which combine high damping capacity with good mechanical properties can provide attractive technical and economic solutions to problems involving seismic, shock and vibration isolation. To meet these trends, we have developed a new high damping Fe-17%Mn alloy. Also, the alloy has advantages of good mechanical properties and is more economical than any other known damping alloys (a quarter the cost of non-ferrous damping alloy). Thus, the high damping Fe-17%Mn alloy can be widely applied to household appliances, automobiles, industrial facilities and power plant components with its excellent damping capacity (SDC, 30%) and mechanical property (T.S. 700 MPa). It is the purpose of this paper to introduce the characterization of the high damping Fe-17%Mn alloy and the results of retrofit of several such applications. (orig.)
ANALISIS PENYEBAB BANJIR KALI JUANA
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Teguh Marhendi
2017-04-01
Full Text Available Kali Juana yang berada di Kabupaten Pati dan Kudus serta sebagian kecil di Kabupaten Grobogan dan Blora, merupakan kawasan banjir. Kejadian banjir di Kali Juana, sudah menjadi rutinitas setiap musim hujan.Dari Januari sampai bulan Mei 2016tercatat terjadi 11 kejadian banjir dibeberapa wilayah, seperti Kecamatan Kaliwungu, Undaan dan Mejobo (Kab. Kudus serta Pati, Margorejo dan Juwana (Kab. Pati. Kali Juana merupakan bifurkasi Kali Serang pada Pintu Wilalung, yang berfungsi sebagai pintu pengatur banjir (dibangun pada zaman Belanda tahun 1918, melalui Kali Babalan menuju ke Kali Juana. Tulisan inidimaksudkan untuk menganalisis penyebab kejadian banjir di Kali Juana. Analisis dilakukan dengan melakukan kajani dan analisis hujan serta mekanisme aliran. Hasil analisis menunjukkan bahwa kondisi Kali Juana dari pertemuan Kali Logung di pintu Wilalung sampai hilir telah mengalami pendangkalan akibat kemiringan dasar atau topografi yang landai, dan mengakibatkan mudah terjadi sedimentasi sehingga mengurangi kapasitas pengaliran. Hal ini menyebabkan luapan banjir sering menggenangi wilayah Kabupaten Kudus dan Pati.
The DAMPE silicon–tungsten tracker
Energy Technology Data Exchange (ETDEWEB)
Azzarello, P., E-mail: philipp.azzarello@unige.ch [Département de Physique Nucléaire et Corpusculaire, University of Geneva, Geneva (Switzerland); Ambrosi, G. [Istituto Nazionale di Fisica Nucleare Sezione di Perugia, Perugia (Italy); Asfandiyarov, R. [Département de Physique Nucléaire et Corpusculaire, University of Geneva, Geneva (Switzerland); Bernardini, P. [Dipartimento di Matematica e Fisica “E. De Giorgi”, Università del Salento, Lecce (Italy); Istituto Nazionale di Fisica Nucleare Sezione di Lecce, Lecce (Italy); Bertucci, B.; Bolognini, A. [Istituto Nazionale di Fisica Nucleare Sezione di Perugia, Perugia (Italy); Dipartimento di Fisica e Geologia, Università di Perugia, Perugia (Italy); Cadoux, F. [Département de Physique Nucléaire et Corpusculaire, University of Geneva, Geneva (Switzerland); Caprai, M. [Istituto Nazionale di Fisica Nucleare Sezione di Perugia, Perugia (Italy); De Mitri, I. [Dipartimento di Matematica e Fisica “E. De Giorgi”, Università del Salento, Lecce (Italy); Istituto Nazionale di Fisica Nucleare Sezione di Lecce, Lecce (Italy); Domenjoz, M. [Département de Physique Nucléaire et Corpusculaire, University of Geneva, Geneva (Switzerland); Dong, Y. [Institute of High Energy Physics, Chinese Academy of Sciences, Beijing (China); Duranti, M. [Istituto Nazionale di Fisica Nucleare Sezione di Perugia, Perugia (Italy); Dipartimento di Fisica e Geologia, Università di Perugia, Perugia (Italy); Fan, R. [Institute of High Energy Physics, Chinese Academy of Sciences, Beijing (China); and others
2016-09-21
The DArk Matter Particle Explorer (DAMPE) is a spaceborne astroparticle physics experiment, launched on 17 December 2015. DAMPE will identify possible dark matter signatures by detecting electrons and photons in the 5 GeV–10 TeV energy range. It will also measure the flux of nuclei up to 100 TeV, for the study of the high energy cosmic ray origin and propagation mechanisms. DAMPE is composed of four sub-detectors: a plastic strip scintillator, a silicon–tungsten tracker–converter (STK), a BGO imaging calorimeter and a neutron detector. The STK is composed of six tracking planes of 2 orthogonal layers of single-sided micro-strip detectors, for a total detector surface of ca. 7 m{sup 2}. The STK has been extensively tested for space qualification. Also, numerous beam tests at CERN have been done to study particle detection at silicon module level, and at full detector level. After description of the DAMPE payload and its scientific mission, we will describe the STK characteristics and assembly. We will then focus on some results of single ladder performance tests done with particle beams at CERN.
Directory of Open Access Journals (Sweden)
Peter Garlans Sina
2012-10-01
Full Text Available Abstract: Analysis of Economic Literacy. The aim of this research is as an effort to increase economic literacy for individuals and households who want to achieve prosperity. Therefore, the obligation of improving the economic literacy needs to be done in a well-planned manner and come from the strong intention to learn in order to improve the economic literacy. It could have an effect on the assets accumulation, a better debt management, as a protection, as well as to increase savings and managing spending intelligently. Keyword: economic literacy, asset, debt, protection, saving, spending Abstrak: Analisis Literasi Ekonomi. Tulisan ini bertujuan sebagai upaya meningkatkan literasi ekonomi bagi individu maupun rumah tangga yang menginginkan mencapai kesejahteraan. Oleh karena itu, kewajiban meningkatkan literasi ekonomi perlu dilakukan secara terencana dan diawali dari niat untuk belajar meningkatkan literasi ekonomi karena dapat berefek pada akumulasi aset, pengelolaan utang yang tepat, proteksi, meningkatkan tabungan dan cerdas mengelola pengeluaran. Kata kunci: literasi ekonomi, aset, utang, proteksi, menabung, pengeluaran
Viscous damping of toroidal angular momentum in tokamaks
Energy Technology Data Exchange (ETDEWEB)
Stacey, W. M. [Georgia Tech Fusion Research Center, Atlanta, Georgia 30332 (United States)
2014-09-15
The Braginskii viscous stress tensor formalism was generalized to accommodate non-axisymmetric 3D magnetic fields in general toroidal flux surface geometry in order to provide a representation for the viscous damping of toroidal rotation in tokamaks arising from various “neoclassical toroidal viscosity” mechanisms. In the process, it was verified that the parallel viscosity contribution to damping toroidal angular momentum still vanishes even in the presence of toroidal asymmetries, unless there are 3D radial magnetic fields.
International Nuclear Information System (INIS)
Han, Y.H.; Park, B.J.; Jung, S.Y.; Han, S.C.; Lee, W.R.; Bae, Y.C.
2013-01-01
Highlights: ► We made a 35 kWh superconductor flywheel energy storage system. ► The damping coefficient of the superconductor bearing was increased over 3000 N s/m. ► The source of damping was discussed. -- Abstract: A 35 kWh Superconductor Flywheel Energy Storage system (SFES) using hybrid bearing sets, which is composed of a high temperature superconductor (HTS) bearing and an active magnet damper (AMD), has been developed at KEPCO Research Institute (KEPRI). Damping is a source of energy loss but necessary for the stability of the flywheel system. We found that the damping of HTS bearings can be improved by thermal insulating bolts, which play a role of passive type external damper. To investigate the source of the increased damping, damping coefficients were measured with HTS bearings using insulating bolts made of three kinds of polymer materials. The damping coefficient was raised over 3000 N s/m in the case of PEEK bolts. The value was almost a quarter of the AMD. In this study, thermoelastic and Coulomb friction damping mechanisms are discussed. The main damping mechanism was the thermoelastic damping of the bolts themselves. And interfacial gap between the insulating bolt and metal chamber, which increased during the cooling process, was considered to be the cause of the anisotropic damping coefficients. Finally, the effects of the HTS bearings on the first critical speed are shown
Reducing extrinsic damping of surface acoustic waves at gigahertz frequencies
Energy Technology Data Exchange (ETDEWEB)
Gelda, Dhruv, E-mail: gelda2@illinois.edu; Sadhu, Jyothi; Ghossoub, Marc G.; Ertekin, Elif [Department of Mechanical Science and Engineering, University of Illinois, Urbana, Illinois 61801 (United States); Sinha, Sanjiv [Department of Mechanical Science and Engineering, University of Illinois, Urbana, Illinois 61801 (United States); Micro and Nanotechnology Laboratory, University of Illinois, Urbana, Illinois 61801 (United States)
2016-04-28
High-frequency surface acoustic waves (SAWs) in the gigahertz range can be generated using absorption from an ultrafast laser in a patterned metallic grating on a substrate. Reducing the attenuation at these frequencies can yield better sensors as well as enable them to better probe phonon and electron-phonon interactions near surfaces. It is not clear from existing experiments which mechanisms dominate damping at high frequencies. We calculate damping times of SAWs due to various mechanisms in the 1–100 GHz range to find that mechanical loading of the grating on the substrate dominates dissipation by radiating energy from the surface into the bulk. To overcome this and enable future measurements to probe intrinsic damping, we propose incorporating distributed acoustic Bragg reflectors in the experimental structure. Layers of alternating materials with contrasting acoustic impedances embedded a wavelength away from the surface serve to reflect energy back to the surface. Using numerical simulations, we show that a single Bragg reflector is sufficient to increase the energy density at the surface by more than five times. We quantify the resulting damping time to find that it is longer than the intrinsic damping time. The proposed structure can enable future measurements of intrinsic damping in SAWs at ∼100 GHz.
PENERAPAN ANALISIS SWOC DALAM RENCANA STRATEGIS PENDIDIKAN
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Hardianto -
2018-01-01
Full Text Available Analisis SWOC merupakan salah satu langkah yang bisa diambil dalam membuat sebuah rencana strategis pendidikan. Analisis ini dilakukan untuk melihat secara mendalam situasi internal dan eksternal organisasi. Situasi internal yang dilihat adalah kekuatan (Strenghts dan kelemahan (Weaknesses organisasi pendidikan. Situasi eksternal berupa peluang (Opportinities dan tantangan (Challenges. Untuk membuat sebuah rencana strategis yang baik dapat dilakukan dengan menganalisis setiap kekuatan, kelemahan, peluang dan tantangan. Teknik kartu salju (snow card bisa digunakan dalam melakukan analisis SWOC. Hasil analisis tersebut nantinya akan melahirkan kombinasi strategi kekuatan-peluang, kekuatan-tantangan, kelemahan-peluang dan kelemahan-tantangan.
DAMPING OF SUBSYNCHRONOUS MODES OF OSCILLATIONS
Directory of Open Access Journals (Sweden)
JAGADEESH PASUPULETI
2006-06-01
Full Text Available The IEEE bench mark model 2 series compensated system is considered for analysis. It consists of single machine supplying power to infinite bus through two parallel lines one of which is series compensated. The mechanical system considered consists of six mass, viz, high pressure turbine, intermediate pressure turbine, two low pressure turbines, generator and an exciter. The excitation system considered is IEEE type 1 with saturation. The auxiliary controls considered to damp the unstable subsynchronous modes of oscillations are Power System Stabilizer (PSS and Static var Compensator (SVC. The different cases of power system stabilizer and reactive power controls are adapted to study the effectiveness of damping these unstable subsynchronous modes of oscillations.
Relativity damps OPEP in nuclear matter
International Nuclear Information System (INIS)
Banerjee, M.K.
1998-06-01
Using a relativistic Dirac-Brueckner analysis the OPEP contribution to the ground state energy of nuclear matter is studied. In the study the pion is derivative-coupled. The author finds that the role of the tensor force in the saturation mechanism is substantially reduced compared to its dominant role in a usual nonrelativistic treatment. He shows that the damping of derivative-coupled OPEP is actually due to the decrease of M * /M with increasing density. He points out that if derivative-coupled OPEP is the preferred form of nuclear effective lagrangian nonrelativistic treatment of nuclear matter is in trouble. Lacking the notion of M * it cannot replicate the damping. He suggests an examination of the feasibility of using pseudoscalar coupled πN interaction before reaching a final conclusion about nonrelativistic treatment of nuclear matter
Energy Technology Data Exchange (ETDEWEB)
Singh, Subhash; Pal, Kaushik, E-mail: pl_kshk@yahoo.co.in
2017-01-15
Interface between ceramic particulate and matrix is known to control the response of the materials and functionality of the composite. Among numerous physical properties, grain structure of the materials has also played a significant role in defining the behaviour of metal matrix composites. Usually, silicon carbide (SiC) particles show poor interfacial wettability in aluminium melt. Herein, we were successfully synthesized magnesium oxide (MgO) and nanocrystalline magnesium aluminate (MgAl{sub 2}O{sub 4}) spinel coated silicon carbide (SiC) core-shell micro-composites through sol-gel technique to improve the wettability of dispersoids. Core-shell structures of submicron size were thoroughly investigated by various characterization techniques. Further, aluminium matrix composites incorporated with pristine SiC, MgO grafted SiC and MgAl{sub 2}O{sub 4} grafted SiC particles were fabricated by stir casting technique, respectively. Additionally, as-cast composites were processed via friction stir processing (FSP) technique to observe the influence of grain refinement on mechanical and damping properties. Electron back scattered diffraction (EBSD), Field emission scanning electron microscopy (FE-SEM) and X-ray energy dispersion spectroscopy (EDX) analysis were conducted for investigating grain size refinement, adequate dispersion, stability and de-agglomeration of encapsulated SiC particles in aluminium matrix. The mechanical as well as thermal cyclic (from − 100 to 400 °C) damping performance of the as-cast and friction stir processed composites were studied, respectively. Finally, the enhanced properties were attributable to reduced agglomeration, stabilization and proper dispersion of the tailored SiC particles Al matrix. - Highlights: •Synthesizing a novel coating layer of MgO and MgAl{sub 2}O{sub 4} spinel onto SiC particles •Significant improvement in UTS and hardness by reinforcing tailored SiC in Al •Significant grain refinements were obtained through
Frequency Dependence of Damping and Compliance in Loudspeaker Suspensions
DEFF Research Database (Denmark)
Thorborg, Knud; Tinggaard, Carsten; Agerkvist, Finn T.
2010-01-01
]. It is an empirical model mathematically describing the effects of visco-elasticity in loudspeaker suspensions. The evaluation is to a high degree based on test loudspeakers with rubber surrounds with a high content of plasticizer combining high compliance and high damping. This is very effective to reduce rim...... resonances, but less used in high quality loudspeakers today – where “Low Loss Rubber Surround” is currently seen as a marketing feature, as it is expected to have positive impact on sound quality. The plasticized type of surround shows significant creep, followed by compliance and damping increasing towards...... - with the additives normally used to adjust stiffness and damping - neither frequency dependency of compliance nor creep are significant problems. Despite this, experience shows that frequency dependent mechanical damping nevertheless might be present. In this paper some modifications to the LOG-model are proposed...
The Duffing oscillator with damping
DEFF Research Database (Denmark)
Johannessen, Kim
2015-01-01
An analytical solution to the differential equation describing the Duffing oscillator with damping is presented. The damping term of the differential equation and the initial conditions satisfy an algebraic equation, and thus the solution is specific for this type of damping. The nonlinear term...... of the differential equation is allowed to be considerable compared to the linear term. The solution is expressed in terms of the Jacobi elliptic functions by including a parameter-dependent elliptic modulus. The analytical solution is compared to the numerical solution, and the agreement is found to be very good....... It is established that the period of oscillation is shorter compared to that of a linearized model but increasing with time and asymptotically approaching the period of oscillation of the linear damped model. An explicit expression for the period of oscillation has been derived, and it is found to be very accurate....
Damping in aerospace composite materials
Agneni, A.; Balis Crema, L.; Castellani, A.
Experimental results are presented on specimens of carbon and Kevlar fibers in epoxy resin, materials used in many aerospace structures (control surfaces and wings in aircraft, large antennas in spacecraft, etc.). Some experimental methods of estimating damping ratios are first reviewed, either in the time domain or in the frequency domain. Some damping factor estimates from experimental tests are then shown; in order to evaluate the effects of the aerospace environment, damping factors have been obtained in a typical range of temperature, namely between +120 C and -120 C, and in the pressure range from room pressure to 10 exp -6 torr. Finally, a theoretical approach for predicting the bounds of the damping coefficients is shown, and prediction data are compared with experimental results.
Amplitude damping of vortex modes
CSIR Research Space (South Africa)
Dudley, Angela L
2010-09-01
Full Text Available An interferometer, mimicking an amplitude damping channel for vortex modes, is presented. Experimentally the action of the channel is in good agreement with that predicted theoretically. Since we can characterize the action of the channel on orbital...
Emittance damping considerations for TESLA
International Nuclear Information System (INIS)
Floettmann, K.; Rossbach, J.
1993-03-01
Two schemes are considered to avoid very large damping rings for TESLA. The first (by K.F.) makes use of the linac tunnel to accomodate most of the damping 'ring' structure, which is, in fact, not a ring any more but a long linear structure with two small bends at each of its ends ('dog-bone'). The other scheme (by J.R.) is based on a positron (or electron, respectively) recycling scheme. It makes use of the specific TESLA property, that the full bunch train is much longer (240 km) than the linac length. The spent beams are recycled seven times after interaction, thus reducing the number of bunches to be stored in the damping ring by a factor of eight. Ultimately, this scheme can be used to operate TESLA in a storage ring mode ('storage linac'), with no damping ring at all. Finally, a combination of both schemes is considered. (orig.)
Vibration damping method and apparatus
Redmond, James M.; Barney, Patrick S.; Parker, Gordon G.; Smith, David A.
1999-01-01
The present invention provides vibration damping method and apparatus that can damp vibration in more than one direction without requiring disassembly, that can accommodate varying tool dimensions without requiring re-tuning, and that does not interfere with tool tip operations and cooling. The present invention provides active dampening by generating bending moments internal to a structure such as a boring bar to dampen vibration thereof.
Analisis Cadangan Devisa Indonesia
Directory of Open Access Journals (Sweden)
Lusia Bunga Uli
2016-09-01
Full Text Available Abstract This study aims to determine the relationship between variables export, import, and exchange rate against Foreign Exchange Reserves in Indonesia. The data used in the empirical study of a sequence of data monthly time of year 2011.01 through 2014.12 from Bank Indonesia and the Central Statistics Agency (BPS. The analysis tool used is Auto Regression Vector Model (VAR. The results of this study indicate that the one-way relationship between the variables of foreign reserves and export. Then one-way relationship between exchange rate and exports. Lastly, there is a two-way relationship between imports and foreign exchange reserves, two-way relationship between exchange rate and foreign exchange reserves, two-way relationship between imports and exports, two-way relationship between the exchange rate and imports. The results also showed foreign exchange reserves are significantly influenced by the movement itself at a probability of 1 %. Export variable negative and not significantly affect the foreign exchange reserves. While imports of positive and not significant to the foreign exchange reserves. Foreign Exchange Reserves Indonesia is positively influenced by the exchange rate and not significant. Keywords: Foreign exchange reserves, exports, imports, exchange rate Abstrak. Penelitian ini bertujuan untuk mengetahui seberapa keterkaitan antar variabel ekspor, impor, dan nilai tukar rupiah terhadap Cadangan Devisa Indonesia. Data yang digunakan dalam kajian empiris ini merupakan data runtutaan waktu bulanan dari tahun 2011.01 sampai 2014. 12 yang berasal dari Bank Indonesia dan Badan Pusat Statistik (BPS. Alat analisis yang digunakan yaitu Vector Autoregression Model (VAR. Hasil dari penelitian ini menunjukkan bahwa hubungan searah antara variabel cadangan devisa ke ekspor. Lalu hubungan searah antara kurs terhadap ekspor Terakhir, terdapat hubungan dua arah antara impor dan cadangan devisa, hubungan dua arah antara kurs dan cadangan
Analisis Semiotik Sajak Bulang Cahaya
Directory of Open Access Journals (Sweden)
Junaidi Junaidi
2014-11-01
Full Text Available Penelitian ini bertujuan menggali makna tanda yang terdapat dalam sajak Bulang Cahaya karya Rida K Liamsi. Untuk menggali makna itu, pendekatan analisis semiotik Roland Barthes digunakan. Hasil penelitian menunjukkan bahwa sajak ini berisi tanda-tanda bersumber dari kosa kata Melayu lama. Sajak ini juga berisi simbol-simbol yang berkaitan dengan kehidupan orang Melayu. Penggunaan kata-kata Melayu lama dan simbol Melayu memperkuat setting Melayu dalam sajak ini. Analisis makna menunjukkan bahwa seseorang merasakan kedukaan sangat mendalam ketika cintanya harus berakhir, tetapi ia terus merasakan kerinduan dengan kekasihnya yang telah pergi. Mitos cinta yang terdapat dalam pusinya adalah orang tahu bahwa putus cinta itu menyakitkan tetapi orang tetap saja jatuh cinta.
Analisis Industri Ritel Di Indonesia
Soliha, Euis
2008-01-01
This article presents an overview the analisys of retail industry in Indonesia.Retail industry in Indonesia grow rapidly. Industrial presence of modern retailbasically exploits public shopping pattern especially middle-weight and to which donot want to mill around in traditional market. Analysis Five Forces is used toanalysis retail industry. Analysis five force is bargaining power of buyers,bargaining power of suppliers, threat of new entrants, threat of new substituteproducts, and rivalry a...
ANALISIS POSITIONING RESTORAN CEPAT SAJI
Directory of Open Access Journals (Sweden)
Osa Omar Sharif
2017-04-01
Full Text Available Penelitian ini bertujuan untuk meneliti positioning restoran cepat saji McDonald's, Kentucky Fried Chicken, California Fried Chicken, A&W, dan Texas Chicken. Penelitian dilakukan di Kota Bandung dengan mengambil sebanyak 400 responden. Analisis yang digunakan dalam penelitian ini adalah analisis multidimensional scaling, analisis memberikan gambaran positioning dari restoran cepat saji yang ditampilkan dalam perceptual map. Restoran cepat saji yang memiliki layanan paling baik adalah McD dan yang memiliki layanan paling buruk adalah CFC. Restoran cepat saji yang memiliki rasa makanan paling enak adalah McD dan yang memiliki rasa makanan tidak enak adalah CFC. KFC dinilai paling ideal karena selalu berhasil menduduki peringkat satu dan dua jika dilihat dari sudut pandang restoran cepat saji yang lain. Pesaing terdekat McD adalah KFC. McD mendapatkan ranking pertama dari segi atribut layanan, kebersihan, variasi makanan, dan rasa makanan. Dengan posisi seperti ini McD seharusnya tetap menjaga kualitas layanan, kebersihan, variasi makanan, dan rasa makanan agar konsumen tetap memilih untuk datang ke McD. KFC sebaiknya tetap menjaga suasana yang membuat konsumen nyaman akan suasana di dalam atau diluar restoran
The influence of microseismic perturbations on a cold damped electrometer
Milatz, J.M.W.; Wapstra, A.H.
1953-01-01
It is proved that the excess fluctuation of an electrometer above the electrical and mechanical Brownian movements found in a former investigation was due to microseismic movements of the soil. A theory is developed of the influence of mechanical perturbations on a cold damped 1) electrometer. This
Energy Technology Data Exchange (ETDEWEB)
Beltran Fernandez, Juan Alfonso; Hernandez Gomez, Luis H; Urriolagoitia Calderon, Guillermo; Villa y Rabasa, Gabriel; Rodriguez, Gustavo Ricardo; Mendoza Nunez, Maribel A [Instituto Politecnico Nacional, Zacatenco (Mexico)
2004-10-15
In this piece of work some fracture testings on specimens with a lateral fracture are made to analyze the resultant stress state around of the tip of the fracture and the way in which the strength of the material is modified to get the fracture toughness, to the load mode I. Also, it is explained the way in which mechanic properties were got in the Polymetil-Methacylate, (PMMA), such as: modulus of elasticity, maximum tensile stress, yielding stress and stress-unitary strain, stress-rate and strain-rate curves, throughout of the carry out of the tensile testing. With the objective to know the real mechanical behavior with the initial loading conditions established and different testing velocities. All and each one of the results are calculated experimental and numerically and validated throughout of the finite element method, using the software ANSYS 5.5.3. [Spanish] En este trabajo se efectuan pruebas de fractura en especimenes con una grieta lateral, para analizar el estado de esfuerzos resultantes alrededor de la punta de la grieta y la forma en que se afecta la resistencia del material a fin de obtener la tenacidad de fractura para el modo de carga I. Ademas, se explica la forma como se obtienen las propiedades mecanicas en el polimetil metacrilato (PMMA), tales como: modulo de elasticidad, esfuerzo normal maximo, esfuerzo de cadencia y las curvas esfuerzo-deformacion unitaria, esfuerzo-tiempo (stress-rate) y deformacion-tiempo (strain-rate), a traves de la realizacion de la prueba de tension. Se busca conocer el comportamiento mecanico real ante las condiciones de carga establecidas y a distintas velocidades de prueba. Todo y cada uno de los resultados se efectuan de manera experimental y son evaluados numericamente a traves del metodo del elemento finito, con el programa ANSYS 5.5.3.
Transport description of damped nuclear reactions
International Nuclear Information System (INIS)
Randrup, J.
1983-04-01
Part I is an elementary introduction to the general transport theory of nuclear dynamics. It can be read without any special knowledge of the field, although basic quantum mechanics is required for the formal derivation of the general expression for the transport coefficients. The results can also be used in a wider context than the present one. Part II gives the student an up-to-date orientation about recent progress in the understanding of the angular-momentum variables in damped reactions. The emphasis is here on the qualitative understanding of the physics rather than the, at times somewhat tedious, formal derivations
Mouhot, Clé ment; Villani, Cé dric
2011-01-01
of regularity between kinetic and spatial variables, rather than exchanges of energy; phase mixing is the driving mechanism. The analysis involves new families of analytic norms, measuring regularity by comparison with solutions of the free transport equation
International Nuclear Information System (INIS)
Ware, A.G.
1987-01-01
A pipe damping research program is being conducted for the United States Nuclear Regulatory Commission at the Idaho National Engineering Laboratory to establish more realistic, best-estimate damping values for use in dynamic structural analyses of piping systems. As part of this program, tests were conducted on a 5-in. (128 mm ID) laboratory piping system to determine the effects of pressure, support configuration, insulation and response amplitude on damping. The tests were designed to produce a wide range of damping values, from very low damping in lightly excited uninsulated systems with few supports, to higher damping under conditions of either/or insulation, high level excitation, and various support arrangements. The effect of pressure at representative seismic levels was considered to be minimal. The supports influence damping at all excitation levels; damping was highest when a mechanical snubber was present in the system. The addition of insulation produced a large increase in damping for the hydraulic shaker excitation tests, but there was no comparable increase for the snapback excitation tests. Once a response amplitude of approximately one-half yield stress was reached, overall damping increased to relatively high levels (>10% of critical)
Energy Technology Data Exchange (ETDEWEB)
Diaz-Guerra, J P
1972-07-01
The efficiency of the compounds GeO{sub 2}, Li{sub 2}B{sub 4}O{sub 7}, Li{sub 2}CO{sub 3}, SiO{sub 2} and SrCO{sub 3} as spectrochemical buffers, in the development of a semiquantitative spectrographic method of analysis, that can be applied to the determination of 47 elements in different matrices, has been tested. It has been shown that trough the use of Li{sub 2}B{sub 4}O{sub 7} or Geo{sub 2} adequate accuracy is obtained, attaining with the latter the detection of much lower concentrations, specially for the elements Mo. Ti, V and W. In order to account for the different behaviour of these elements their volatilization mechanism has been studied. MoB{sub 2}, TiB{sub 2}, VB{sub 2}.{delta}WB and {epsilon}-WB were found, by x-ray diffraction analysis, to be reaction products in the case of mixtures with Li{sub 2}B{sub 4}O{sub 7}. (Author)
Robust Rudder Roll Damping Control
DEFF Research Database (Denmark)
Yang, C.
The results of a systematic research to solve a specific ship motion control problem, simultaneous roll damping and course keeping using the rudder are presented in this thesis. The fundamental knowledge a priori is that rudder roll damping is highly sensitive to the model uncertainty, therefore H-infinity...... theory is used to deal with the problem. The necessary mathematical tools and the H-Infinity theory as the basis of controller design are presented in Chapter 2 and 3. The mu synthesis and the D-K iteration are introduced in Chapter 3. The ship dynamics and modeling technology are discussed in Chapter 4...
Damping ring designs and issues
International Nuclear Information System (INIS)
Wolski, Andrzej; Decking, Winfried
2003-01-01
The luminosity performance of a future linear collider (LC) will depend critically on the performance of the damping rings. The design luminosities of the current LC proposals require rings with very short damping times, large acceptance, low equilibrium emittance and high beam intensity. We discuss the design strategies for lattices achieving the goals of dynamical stability, examine the challenges for alignment and coupling correction, and consider a variety of collective effects that threaten to limit beam quality. We put the design goals in context by referring to the experience of operating facilities, and outline the further research and development that is needed
The Microstructural Basis of Damping in High Damping Alloys
1989-09-01
This transformation is diffusionless and is characterized by the cooperative movement of atoms in a given section of crystal. Removal of the stress...martensites. The cooperative movement of atoms causes large internal friction and high damping. The temperature range in which this transformation can
Squeeze-Film Air Damping of a Five-Axis Electrostatic Bearing for Rotary Micromotors.
Wang, Shunyue; Han, Fengtian; Sun, Boqian; Li, Haixia
2017-05-13
Air-film damping, which dominates over other losses, plays a significant role in the dynamic response of many micro-fabricated devices with a movable mass suspended by various bearing mechanisms. Modeling the damping characteristics accurately will be greatly helpful to the bearing design, control, and test in various micromotor devices. This paper presents the simulated and experimental squeeze-film air damping results of an electrostatic bearing for use in a rotary high-speed micromotor. It is shown that the boundary condition to solve the three-dimensional Reynolds equation, which governs the squeeze-film damping in the air gap between the rotor and its surrounding stator sealed in a three-layer evacuated cavity, behaves with strong cross-axis coupling characteristics. To accurately characterize the damping effect, a set of multiphysics finite-element simulations are performed by computing both the rotor velocity and the distribution of the viscous damping force acting on the rotor. The damping characteristics varying with several key structure parameters are simulated and discussed to optimize the device structure for desirable rotor dynamics. An electrical measurement method is also proposed and applied to validate the numerical results of the damping coefficients experimentally. Given that the frequency response of the electric bearing is critically dependent on the damping coefficients at atmospheric pressure, a solution to the air-film damping measurement problem is presented by taking approximate curve fitting of multi-axis experimental frequency responses. The measured squeeze-film damping coefficients for the five-axis electric bearing agrees well with the numerical solutions. This indicates that numerical multiphysics simulation is an effective method to accurately examine the air-film damping effect for complex device geometry and arbitrary boundary condition. The accurate damping coefficients obtained by FEM simulation will greatly simplify the design
Collisionless damping of nonlinear dust ion acoustic wave due to dust charge fluctuation
International Nuclear Information System (INIS)
Ghosh, Samiran; Chaudhuri, Tushar K.; Sarkar, Susmita; Khan, Manoranjan; Gupta, M.R.
2002-01-01
A dissipation mechanism for the damping of the nonlinear dust ion acoustic wave in a collisionless dusty plasma consisting of nonthermal electrons, ions, and variable charge dust grains has been investigated. It is shown that the collisionless damping due to dust charge fluctuation causes the nonlinear dust ion acoustic wave propagation to be described by the damped Korteweg-de Vries equation. Due to the presence of nonthermal electrons, the dust ion acoustic wave admits both positive and negative potential and it suffers less damping than the dust acoustic wave, which admits only negative potential
Influence of wire EDM parameters on the damping behaviour of A356.2 aluminum alloy
Energy Technology Data Exchange (ETDEWEB)
Prasad, Dora Siva, E-mail: dorasivaprasad@gmail.com [Dept of Mechanical Engineering, GITAM University, Visakhapatnam, 530045 (India); Shoba, Chintada [Dept of Industrial Engineering, GITAM University, Visakhapatnam, 530045 (India); Varma, Kalidindi Rahul [Dept of Mechanical Engineering, RAGHU College of Engineering, Visakhapatnam (India); Khurshid, Abdul [M.Tech (CAD/CAM), Dept of Mechanical Engineering, GITAM University, Visakhapatnam, 530045 (India)
2015-10-15
The effect of different Wire electrical discharge machining (WEDM) process parameters on the damping behavior of A356.2 aluminum alloy is investigated. In the present investigation pulse on time (T{sub ON}), pulse off time (T{sub OFF}) and peak current (IP) which are considered to be the most significant process parameters from the previous studies are varied using one factor at a time approach, to study the effect on damping behavior of A356.2 aluminum alloy. Damping experiments are performed on a dynamic mechanical analyzer (DMA 8000) at constant strain under dual cantilever mode over a frequency range of 1–100 Hz at room temperature. The scanning electron microscope was used for characterization of the wire EDMed samples. Experimental results reveal that the damping behavior greatly depends on the wire EDM process parameters. The related mechanisms are presented. - Highlights: • Damping capacity increase with the increase in frequency. • Increasing pulse on time increases the damping capacity of aluminum alloy. • The damping capacity was found to decrease with the increase in pulse off time. • No significant change in damping capacity was noticed with varied peak current. • The formation of white layer plays an important role in the damping behavior.
Dampness in buildings and health
DEFF Research Database (Denmark)
Bornehag, Carl-Gustaf; Blomquist, G.; Gyntelberg, F.
2001-01-01
Several epidemiological investigations concerning indoor environments have indicated that "dampness" in buildings is associated to health effects such as respiratory symptoms, asthma and allergy The aim of the present interdisciplinary review is to evaluate this association as shown in the epidem...
Nonlocal quasilinear damped differential inclusions
Directory of Open Access Journals (Sweden)
Mouffak Benchohra
2002-01-01
Full Text Available In this paper we investigate the existence of mild solutions to second order initial value problems for a class of damped differential inclusions with nonlocal conditions. By using suitable fixed point theorems, we study the case when the multivalued map has convex and nonconvex values.
ANALISIS PERBAIKAN SISTEM PENTANAHAN TELEKOMUNIKASI
Directory of Open Access Journals (Sweden)
Umar Umar
2015-04-01
Hasil dari penelitian ini adalah perbaikan sistem pentanahan site Kampung Baru dengan menggunakan konfigurasi single point connection window (SPCW, untuk mengamankan sistem telekomunikasi dari kebocoran arus dan petir serta imbasnya. Perbaikan sistem pentanahan di site Kampung Baru menggunakan banyak elektroda yang membentuk persegi dikarenakan topografi tempat di sana yang memungkinkan dan efektif adalah menggunakan sistem tersebut. Berdasarkan hasil analisis dan perhitungan perbaikan sistem di site Kampung Baru, didapatkan nilai perhitungan sistem pentanahan adalah 1.34 Ohm serta pengukurannya 1.21-1.25 Ohm.
Marhauser, Frank
2017-06-01
Research and development for superconducting radio-frequency cavities has made enormous progress over the last decades from the understanding of theoretical limitations to the industrial mass fabrication of cavities for large-scale particle accelerators. Key technologies remain hot topics due to continuously growing demands on cavity performance, particularly when in pursuit of high quality beams at higher beam currents or higher luminosities than currently achievable. This relates to higher order mode (HOM) damping requirements. Meeting the desired beam properties implies avoiding coupled multi-bunch or beam break-up instabilities depending on the machine and beam parameters that will set the acceptable cavity impedance thresholds. The use of cavity HOM-dampers is crucial to absorb the wakefields, comprised by all beam-induced cavity Eigenmodes, to beam-dynamically safe levels and to reduce the heat load at cryogenic temperature. Cavity damping concepts may vary, but are principally based on coaxial and waveguide couplers as well as beam line absorbers or any combination. Next generation energy recovery linacs and circular colliders call for cavities with strong HOM-damping that can exceed the state-of-the-art, while the operating mode efficiency shall not be significantly compromised concurrently. This imposes major challenges given the rather limited damping concepts. A detailed survey of established cavities is provided scrutinizing the achieved damping performance, shortcomings, and potential improvements. The scaling of the highest passband mode impedances is numerically evaluated in dependence on the number of cells for a single-cell up to a nine-cell cavity, which reveals the increased probability of trapped modes. This is followed by simulations for single-cell and five-cell cavities, which incorporate multiple damping schemes to assess the most efficient concepts. The usage and viability of on-cell dampers is elucidated for the single-cell cavity since it
Damped Oscillator with Delta-Kicked Frequency
Manko, O. V.
1996-01-01
Exact solutions of the Schrodinger equation for quantum damped oscillator subject to frequency delta-kick describing squeezed states are obtained. The cases of strong, intermediate, and weak damping are investigated.
Nuclear piping system damping data studies
International Nuclear Information System (INIS)
Ware, A.G.; Arendts, J.G.
1985-01-01
A programm has been conducted at the Idaho National Engineering Laboratory to study structural damping data for nuclear piping systems and to evaluate if changes in allowable damping values for structural seismic analyses are justified. The existing pipe damping data base was examined, from which a conclusion was made that there were several sets of data to support higher allowable values. The parameters which most influence pipe damping were identified and an analytical investigation demonstrated that increased damping would reduce the required number of seismic supports. A series of tests on several laboratory piping systems was used to determine the effect of various parameters such as types of supports, amplitude of vibration, frequency, insulation, and pressure on damping. A multiple regression analysis was used to statistically assess the influence of the various parameters on damping, and an international pipe damping data bank has been formed. (orig.)
International Nuclear Information System (INIS)
Shibata, H.; Ito, M.; Hayashi, T.; Chiba, T.; Kobayashi, H.; Kitamura, K.; Ando, K.; Koyanagi, R.
1981-01-01
To clarify the damping characteristics and mechanism in nuclear power plant piping systems, the study group was established and conducted to study SDREP (Seismic Damping Ratio Evaluation Program). As the Phase II of this study, vibration tests were conducted to investigate factors which might contribute to damping characteristics of piping systems. These tests are composed of the next three model tests: 1) The component damping characteristics test of thermal insulator 2) The simplified piping model test 3) The scale model test. In these tests, we studied damping characteristics with emphasis on thermal insulator (mainly calcium silicate insulator). The acceleartion level of pipings is the same as that of the actual seismic response. The excitation was by sinusoidal sweep method using the shaking table and by free vibration method using snapback. (orig./RW)
Damping characteristics of reinforced concrete structures
International Nuclear Information System (INIS)
Hisano, M.; Nagashima, I.; Kawamura, S.
1987-01-01
Reinforced concrete structures in a nuclear power plant are not permitted to go far into the inelasticity generally, even when subjected to strong ground motion. Therefore it is important to evaluate the damping appropriately in linear and after cracking stage before yielding in the dynamic response analysis. Next three dampings are considered of reinforced concrete structures. 1) Internal damping in linear range material damping of concrete without cracks;2) Hysteretic damping in inelastic range material hysteretic damping of concrete due to cracking and yielding;3) Damping due to the energy dissipation into the ground. Among these damping material damping affects dynamic response of a nuclear power plant on hard rock site where damping due to energy dissipation into the ground is scarcely expected. However material damping in linear and slightly nonlinear range have only been assumed without enough experimental data. In this paper such damping is investigated experimentally by the shaking table tests of reinforced concrete box-walls which modeled roughly the outer wall structure of a P.W.R. type nuclear power plant
Semiotika Teks: Sebuah Pendekatan Analisis Teks
Directory of Open Access Journals (Sweden)
Yasraf Amir Piliang
2004-12-01
tanda-tanda yang membentuk apa yang disebut sebagai ‘teks’. Analisis teks, menurut Roland Barthes, akan menghasilkan makna denotatif, yakni makna tanda yang bersifat eksplisit, dan makna konotatif, yaitu makna tanda lapis kedua yang bersifat implisit.
Risk analysis; Analisis de riesgos
Energy Technology Data Exchange (ETDEWEB)
Baron, J H; Nunez McLeod, J; Rivera, S S [Universidad Nacional de Cuyo, Mendoza (Argentina). Instituto de Capacitacion Especial y Desarrollo de Ingenieria Asistida por Computadora (CEDIAC)
1997-07-01
This book contains a selection of research works performed in the CEDIAC Institute (Cuyo National University) in the area of Risk Analysis, with specific orientations to the subjects of uncertainty and sensitivity studies, software reliability, severe accident modeling, etc. This volume presents important material for all those researches who want to have an insight in the risk analysis field, as a tool to solution several problems frequently found in the engineering and applied sciences field, as well as for the academic teachers who want to keep up to date, including the new developments and improvements continuously arising in this field. [Spanish] Este libro contiene una seleccion de trabajos de investigacion realizados dentro del Instituto de Capacitacion Especial y Desarrollo de la Ingenieria Asistida por Computadora en el area del analisis de riesgos, con una orientacion hacia el estudio de incertidumbres y sensibilidad, confiabilidad de software, modelacion de accidentes severos, etc. Este volumen recoge un material de indudable importancia e interes para todos aquellos investigadores y profesionales que desean incursionar en este campo del analisis de riesgos como herramienta para la solucion de problemas frecuentemente encontrados en la ingenieria y las ciencias aplicadas, asi como para los academicos que desean mantenerse al dia, conociendo los nuevos desarrollos y tecnicas que constantemente aparecen en su area.
Analisis Kebijakan dan Efektivitas Organisasi
Directory of Open Access Journals (Sweden)
Amir Syarifudin Kiwang
2015-05-01
Full Text Available Penerapan Peraturan Gubernur Nusa Tenggara Timur Nomor 8 Tahun 2011 tentang Organisasi dan Tata Kerja Unit Pelaksana Teknis Pendidikan dan Pelatihan Koperasi dan Usaha Mikro Kecil dan Menengah pada Dinas Koperasi dan Usaha Mikro Kecil dan Menengah Provinsi Nusa Tenggara Timur adalah dalam rangka untuk meningkatkan efektivitas kerja organisasi pada UPT Diklat Koperasi dan UMKM. Penelitian ini berusaha untuk melihat dampak kebijakan organisasi terhadap efektivitas organisasi dengan menggunakan enam elemen variabel dari kebijakan dan praktik manajemen. Keenam elemen tersebut adalah penetapan tujuan strategis, pencarian dan pemanfaatan sumber daya, lingkungan prestasi, proses komunikasi, kepemimpinan dan pengambilan keputusan, serta adaptasi dan inovasi organisasi. Penelitian kualitatif ini menggunakan pendekatan studi kasus. Teknik analisis data yang digunakan adalah analisis data model Miles dan Huberman, yang terdiri atas reduksi data, display/penyajian data, dan kesimpulan/verifikasi. Hasil penelitian menunjukkan bahwa efektivitas organisasi pada UPT Diklat koperasi dan UMKM belum berjalan secara baik, hal ini dapat dilihat dari beberapa hal antara lain, belum adanya tenaga spesialisasi pengelola diklat dan tenaga khusus (sarjana di bidang perkoperasian dan kondisi lingkungan kerja (lingkungan prestasi pada UPT Diklat koperasi dan UMKM yang belum efektif. Penempatan pegawai juga belum tepat, mutasi ke UPT Diklat Koperasi dan UMKM tidak memperhatikan latar belakang pendidikan dan spesialisasi/keahlian pegawai sehingga membutuhkan waktu dalam proses penyesuaian serta menurunkan jumlah pelaksanaan diklat dikarenakan keterbatasan alokasi dana.
ANALISIS DAYA SAING KEDELAI INDONESIA
Directory of Open Access Journals (Sweden)
Sarwono Sarwono
2014-09-01
Full Text Available RCA (Revealed Comparative Advantage index of soybean in Indonesia from 1983 up to 2013 is less than one, mostly. It means that the competitiveness of soybean in Indonesia is low. The purpose of this study is to analyze the factors influence the soybean competitiveness. OLS (Ordinary Least Square was used as the analysis method. Hypotheses test based on that analysis model is not bias, so that, classic divergence test is needed. It is for getting the Best Linier Unbiased Estimator (BLUE appraisal. T statistic and F statistic were also applied. The result of this research shows that production and export have positive and significant influence. In addition, exchange rate and government policy do not influence the Indonesia soybean competitiveness.Indeks RCA (Revealed Comparative Advantage kedelai Indonesia dari tahun 1983-2013 kecenderungan bernilai kurang dari satu yang berarti daya saing kedelai Indonesia rendah.Penelitian ini bertujuan untuk menganalisis faktor-faktor yang mempengaruhi daya saing kedelai Indonesia.Metode analisis yang digunakan adalah Ordinary Least Square (OLS.Pengujian hipotesis berdasarkan model analisis tersebut tidak bias maka perlu dilakukan uji penyimpangan klasik yang tujuannya agar diperoleh penaksiran yang bersifat Best Linier Unbiased Estimator (BLUE.Pengujian statistik menggunakan uji t statistikdan uji f statistik.Hasil penelitian ini menunjukkan bahwa produksi dan ekspor berpengaruh secara positif dan signifikan terhadap daya saing kedelai Indonesia. Nilai tukar rupiah dan kebijakan pemerintah tidak berpengaruh terhadap daya saing kedelai Indonesia.
The forced harmonic oscillator with damping and thermal effects
International Nuclear Information System (INIS)
Menezes Franca, H. de; Thomaz, M.T.
1984-01-01
Nonperturbative quantum mechanical solutions of the forced harmonic oscillator with radiation reaction damping are obtained from previous analysis based on Stochastic Electrodynamics. The transition to excited states is shown to be to coherent states which follow the classical trajectory. The quantum Wigner distribution in phase space is constructed. All the results are extended to finite temperatures. (Author) [pt
The Lagrangians and Hamiltonians of damped coupled vibrations
International Nuclear Information System (INIS)
Ding Guangtao; Gan Huilan; Zheng Xianfeng; Cui Zhifeng
2012-01-01
In this paper, the analytical mechanization of two kinds of damped coupled vibrations is studied. First, by use of coordinate transformations the equations of motion are transformed into the self-ad- joint form. Secondly, the Lagrangians are obtained according to Engels method. Finally the Lagrangians and Hamiltonians of the original equations are deduced by using the inverse transformation. (authors)
A Look at Damped Harmonic Oscillators through the Phase Plane
Daneshbod, Yousef; Latulippe, Joe
2011-01-01
Damped harmonic oscillations appear naturally in many applications involving mechanical and electrical systems as well as in biological systems. Most students are introduced to harmonic motion in an elementary ordinary differential equation (ODE) course. Solutions to ODEs that describe simple harmonic motion are usually found by investigating the…
Prognostic and predictive value of DAMPs and DAMP-associated processes in cancer
Directory of Open Access Journals (Sweden)
Jitka eFucikova
2015-08-01
Full Text Available It is now clear that human neoplasms form, progress and respond to therapy in the context of an intimate crosstalk with the host immune system. In particular, accumulating evidence demonstrates that the efficacy of most, if not all, chemo- and radiotherapeutic agents commonly employed in the clinic critically depends on the (reactivation of tumor-targeting immune response. One of the mechanisms whereby conventional chemotherapeutics, targeted anticancer agents and radiotherapy can provoke a therapeutically relevant, adaptive immune response against malignant cells is commonly known as „immunogenic cell death (ICD. Importantly, dying cancer cells are perceived as immunogenic only when they emit a set of immunostimulatory signals upon the activation of intracellular stress response pathways. The emission of these signals, which are generally referred to as „damage-associated molecular patterns (DAMPs, may therefore predict whether patients will respond to chemotherapy or not, at least in some settings. Here, we review clinical data indicating that DAMPs and DAMP-associated stress responses might have prognostic or predictive value for cancer patients.
Analisis Harmonisa Inverter PWM Satu Fasa
Rejeki Simanjorang
2008-01-01
Pada tesis ini dianalisis harmonisa inverter PWM satu fasa. Inverter PWM satu fasa yang akan ditinjau adalah inverter satu fasa jembatan penuh (konvensional) dan inverter komposit. Analisis difokuskan pada penentuan pola penyaklaran yang optimum agar pembangkitan harmonisa dan switching losses inverter rendah. Untuk menentukan pola penyaklaran optimum maka dilakukan analisis yang berbasis pada rangkaian ekivalen harmonisa inverter satu fasa. Dengan menggunakan pola penyaklaran optimum, kedua ...
Transit-Time Damping, Landau Damping, and Perturbed Orbits
Simon, A.; Short, R. W.
1997-11-01
Transit-time damping(G.J. Morales and Y.C. Lee, Phys. Rev. Lett. 33), 1534 (1974).*^,*(P.A. Robinson, Phys. Fluids B 3), 545 (1991).** has traditionally been obtained by calculating the net energy gain of transiting electrons, of velocity v, to order E^2* in the amplitude of a localized electric field. This necessarily requires inclusion of the perturbed orbits in the equation of motion. A similar method has been used by others(D.R. Nicholson, Introduction to Plasma Theory) (Wiley, 1983).*^,*(E.M. Lifshitz and L.P. Pitaevskifi, Physical Kinetics) (Pergamon, 1981).** to obtain a ``physical'' picture of Landau damping in a nonlocalized field. The use of perturbed orbits seems odd since the original derivation of Landau (and that of Dawson) never went beyond a linear picture of the dynamics. We introduce a novel method that takes advantage of the time-reversal invariance of the Vlasov equation and requires only the unperturbed orbits to obtain the result. Obviously, there is much reduction in complexity. Application to finite slab geometry yields a simple expression for the damping rate. Equivalence to much more complicated results^2* is demonstrated. This method allows us to calculate damping in more complicated geometries and more complex electric fields, such as occur in SRS in filaments. See accompanying talk.(R.W. Short and A. Simon, this conference.) This work was supported by the U.S. DOE Office of Inertial Confinement Fusion under Co-op Agreement No. DE-FC03-92SF19460.
Study of damping characteristics of fibre reinforced composite aerospace structure
International Nuclear Information System (INIS)
Khan, M.Z.; Saleh, S.; Munir, A.
2006-01-01
Composite materials are used in a variety of high demanding structural applications. Apart from their other preferable properties, they have high-energy dissipation characteristics, which is important aspect when we repeatedly wiggle the system back and forth. It is important to have thorough understanding of material damping behavior; in general materials damping tends to be complex nonlinear function of vibration amplitude, frequency of loading and material formulation. There are number of mathematical models available in literature to obtain hysteresis curves. One approach for identifying damping characteristics used mechanical hysteresis curves. In present work, a phenomenon was observed during testing of fibre reinforced composite beam of an aerospace structure, that for increase load in structure, the path of Force vs. Displacement curve is different than the path of unloading. A plot is generated which indicate the hysteresis loop representing the steady state dynamic behavior of material. The area enclosed by such curves is proportional to energy dissipation per cycle. However, the specific shape of the curve also has important implications for characterizing the specific functional form of the damping. Therefore, it is important to develop methods for accurately accounting for such effects. The current work explores the damping characteristics both theoretically and experimentally. (author)
Research overview on vibration damping of mistuned bladed disk assemblies
Directory of Open Access Journals (Sweden)
Liang ZHANG
2016-04-01
Full Text Available Bladed disk assemblies are very important parts in auto engine and gas turbine, and is widely used in practical engineering. The mistuning existing commonly in the bladed disk assemblies can destroy the vibration characteristics of the bladed disk assemblies, which is one of the reasons for the high cycle fatigue failure of bladed disk assemblies, so it is necessary to research how to reduce the vibration of the bladed disk assemblies. On the basis of the review of relevant research at home and abroad, the mistuning vibration mechanism of the bladed disk assemblies is introduced, and the main technical methods of the vibration damping of bladed disk assemblies are reviewed, such as artificially active mistuning, collision damping, friction damping and optimization of the blade position. Some future research directions are presented.
Design of passive piezoelectric damping for space structures. Final Report Ph.D. Thesis
Hagood, Nesbitt W., IV; Aldrich, Jack B.; Vonflotow, Andreas H.
1994-01-01
Passive damping of structural dynamics using piezoceramic electromechanical energy conversion and passive electrical networks is a relatively recent concept with little implementation experience base. This report describes an implementation case study, starting from conceptual design and technique selection, through detailed component design and testing to simulation on the structure to be damped. About 0.5kg. of piezoelectric material was employed to damp the ASTREX testbed, a 500kg structure. Emphasis was placed upon designing the damping to enable high bandwidth robust feedback control. Resistive piezoelectric shunting provided the necessary broadband damping. The piezoelectric element was incorporated into a mechanically-tuned vibration absorber in order to concentrate damping into the 30 to 40 Hz frequency modes at the rolloff region of the proposed compensator. A prototype of a steel flex-tensional motion amplification device was built and tested. The effective stiffness and damping of the flex-tensional device was experimentally verified. When six of these effective springs are placed in an orthogonal configuration, strain energy is absorbed from all six degrees of freedom of a 90kg. mass. A NASTRAN finite element model of the testbed was modified to include the six-spring damping system. An analytical model was developed for the spring in order to see how the flex-tensional device and piezoelectric dimensions effect the critical stress and strain energy distribution throughout the component. Simulation of the testbed demonstrated the damping levels achievable in the completed system.
Ambient-temperature high damping capacity in TiPd-based martensitic alloys
International Nuclear Information System (INIS)
Xue, Dezhen; Zhou, Yumei; Ding, Xiangdong; Otsuka, Kazuhiro; Lookman, Turab; Sun, Jun; Ren, Xiaobing
2015-01-01
Shape memory alloys (SMAs) have attracted considerable attention for their high damping capacities. Here we investigate the damping behavior of Ti 50 (Pd 50−x D x ) SMAs (D=Fe, Co, Mn, V) by dynamic mechanical analysis. We find that these alloys show remarkably similar damping behavior. There exists a sharp damping peak associated with the B2–B19 martensitic transformation and a high damping plateau (Q −1 ~0.02–0.05) over a wide ambient-temperature range (220–420 K) due to the hysteretic twin boundary motion. After doping hydrogen into the above alloys, a new relaxation-type damping peak appears in the martensite phase over 270–360 K. Such a peak is considered to originate from the interaction of hydrogen atoms with twin boundaries and the corresponding damping capacity (Q −1 ~0.05–0.09) is enhanced by roughly twice that of the damping plateau for each alloy. Moreover, the relaxation peaks are at higher temperatures for the TiPd-based alloys (270–370 K) than for the TiNi-based alloys (190–260 K). We discuss the influence of hydrogen diffusion, mobility of twin boundaries and hydrogen–twin boundary interaction on the temperature range of the relaxation peak. Our results suggest that a martensite, with appropriate values for twinning shear and hydrogen doping level, provides a route towards developing high damping SMAs for applications in desired temperature ranges
Transport description of damped nuclear reactions
International Nuclear Information System (INIS)
Randrup, J.
1984-01-01
This lecture series is concerned with the transport description of damped nuclear reactions. Part 1 is an elementary introduction to the general transport theory of nuclear dynamics. It can be read without any special knowledge of the field, although basic quantum mechanics is required for the formal derivation of the general expressions for the transport coefficients. The results can also be used in a wider context than the present one. Part 2 gives the student an up-to-date orientation about recent progress in the understanding of the angular-momentum variables in damped reactions. The emphasis is here on the qualitative understanding of the physics rather than the, at times somewhat tedious, formal derivations. More detailed presentations are due to be published soon. By necessity entire topics have been omitted. For example, no discussion is given of the calculation of the form factors, and the several instructive applications of the theory to transport of mass and change are not covered at all. For these topics they refer to the literature. It is hoped that the present notes provide a sufficient basis to make the literature on the subject accessible to the student
Modelling of Dampers and Damping in Structures
DEFF Research Database (Denmark)
Høgsberg, Jan Riess
2006-01-01
and the maximum attainable damping are found by maximizing the expression for the damping ratio. The theory is formulated for linear damper models, but may also be applied for non-linear dampers in terms of equivalent linear parameters for stiffness and damping, respectively. The format of the expressions......, and thereby the damping, of flexible structures are generally described in terms of the dominant vibration modes. A system reduction technique, where the damped vibration mode is constructed as a linear combination of the undamped mode shape and the mode shape obtained by locking the damper, is applied....... This two-component representation leads to a simple solution for the modal damping representing the natural frequency and the associated damping ratio. It appears from numerical examples that this system reduction technique provides very accurate results. % Analytical expressions for the optimal tuning...
Multiparticle phenomena and Landau damping
International Nuclear Information System (INIS)
Talman, R.
1987-01-01
The purpose of this paper is to survey various methods of studying multiparticle phenomena in accelerators. Both experimental and theoretical methods are described. An effort has been made to emphasize the intuitive and qualitative aspects rather than the detailed mathematics. Some of the terms or concepts to be explained are coherent and incoherent tunes, normal modes, Landau damping, beam-transfer functions, and feedback. These are all of daily importance in the interpretation of colliding-beam observations and the control of performance
Yang, H. Q.; West, Jeff
2018-01-01
Determination of slosh damping is a very challenging task as there is no analytical solution. The damping physics involves the vorticity dissipation which requires the full solution of the nonlinear Navier-Stokes equations. As a result, previous investigations were mainly carried out by extensive experiments. A systematical study is needed to understand the damping physics of baffled tanks, to identify the difference between the empirical Miles equation and experimental measurements, and to develop new semi-empirical relations to better represent the real damping physics. The approach of this study is to use Computational Fluid Dynamics (CFD) technology to shed light on the damping mechanisms of a baffled tank. First, a 1-D Navier-Stokes equation representing different length scales and time scales in the baffle damping physics is developed and analyzed. Loci-STREAM-VOF, a well validated CFD solver developed at NASA MSFC, is applied to study the vorticity field around a baffle and around the fluid-gas interface to highlight the dissipation mechanisms at different slosh amplitudes. Previous measurement data is then used to validate the CFD damping results. The study found several critical parameters controlling fluid damping from a baffle: local slosh amplitude to baffle thickness (A/t), surface liquid depth to tank radius (d/R), local slosh amplitude to baffle width (A/W); and non-dimensional slosh frequency. The simulation highlights three significant damping regimes where different mechanisms dominate. The study proves that the previously found discrepancies between Miles equation and experimental measurement are not due to the measurement scatter, but rather due to different damping mechanisms at various slosh amplitudes. The limitations on the use of Miles equation are discussed based on the flow regime.
Structural Damping with Friction Beams
Directory of Open Access Journals (Sweden)
L. Gaul
2008-01-01
Full Text Available In the last several years, there has been increasing interest in the use of friction joints for enhancing damping in structures. The joints themselves are responsible for the major part of the energy dissipation in assembled structures. The dissipated work in a joint depends on both the applied normal force and the excitation force. For the case of a constant amplitude excitation force, there is an optimal normal force which maximizes the damping. A ‘passive’ approach would be employed in this instance. In most cases however, the excitation force, as well as the interface parameters such as the friction coefficient, normal pressure distribution, etc., are not constant. In these cases, a ‘semi-active’ approach, which implements an active varying normal force, is necessary. For the ‘passive’ and ‘semi-active’ approaches, the normal force has to be measured. Interestingly, since the normal force in a friction joint influences the local stiffness, the natural frequencies of the assembled structure can be tuned by adjusting the normal force. Experiments and simulations are performed for a simple laboratory structure consisting of two superposed beams with friction in the interface. Numerical simulation of the friction interface requires non-linear models. The response of the double beam system is simulated using a numerical algorithm programmed in MATLAB which models point-to-point friction with the Masing friction model. Numerical predictions and measurements of the double beam free vibration response are compared. A practical application is then described, in which a friction beam is used to damp the vibrations of the work piece table on a milling machine. The increased damping of the table reduces vibration amplitudes, which in turn results in enhanced surface quality of the machined parts, reduction in machine tool wear, and potentially higher feed rates. Optimal positioning of the friction beams is based on knowledge of the mode
Spatially Localized Particle Energization by Landau Damping in Current Sheets
Howes, G. G.; Klein, K. G.; McCubbin, A. J.
2017-12-01
Understanding the mechanisms of particle energization through the removal of energy from turbulent fluctuations in heliospheric plasmas is a grand challenge problem in heliophysics. Under the weakly collisional conditions typical of heliospheric plasma, kinetic mechanisms must be responsible for this energization, but the nature of those mechanisms remains elusive. In recent years, the spatial localization of plasma heating near current sheets in the solar wind and numerical simulations has gained much attention. Here we show, using the innovative and new field-particle correlation technique, that the spatially localized particle energization occurring in a nonlinear gyrokinetic simulation has the velocity space signature of Landau damping, suggesting that this well-known collisionless damping mechanism indeed actively leads to spatially localized heating in the vicinity of current sheets.
Contribution to the damping identification: experimental and numerical approaches
International Nuclear Information System (INIS)
Crambuer, R.
2013-01-01
Since earthquakes are a natural threat in France, it seems reasonable to construct buildings capable of resisting them. Since 1955, A.S. 55 recommendations regulations have taken into account this risk in all new constructions. The rules were created following an earthquake in Orleansville (Algeria) on 9. September 1954 and since then they have been modified in the aftermath of several significant earthquakes. As it stands now, the law requires that measurements of energy dissipation be carried out during the earthquakes in an effective manner. However, at present it is a great challenge to determine this, especially where reinforced concrete structures are concerned. The reason for this is the many different causes of energy dissipation which can be material, such as steel yielding, cracking of the concrete or deterioration of the interface between the Steel/concrete interface or environmental, such as the interactions with neighbouring structures or radiative damping. These dissipations typically creep into the essential pattern of the structures as a uniform, slight damping, and which is heavily quantify such as modal or Rayleigh damping. The challenge is therefore to ascertain how to carry out damping in a way that relies more on the laws of physics themselves. This study aims at bringing some clarifications to this problem. In order to achieve this, two objectives were targeted during the case study: the first consisted in experimentally qualifying and quantifying the sources of damping in concrete, the second aims at developing a method which model both the overall behaviour and the damping in a realistic way with low computational costs. A series of reverse 3-point bending tests were carried out to determine and quantify the mechanisms responsible for damping. This approach was innovative in that the tests were carried out on not only sound beams, but also on pre-damaged beams. When processing the results of these experiments, we focused on the overall
ANALISIS IMPOR BERAS DI INDONESIA
Directory of Open Access Journals (Sweden)
Ratih Kumala Sari
2014-10-01
Full Text Available Abstrak ___________________________________________________________________ Salah satu kebijakan pemerintah untuk memenuhi kebutuhan beras yaitu dengan menggenjot produksi beras dalam negeri. Namun dengan semakin meningkatnya jumlah penduduk akan meningkatkan permintaan terhadap beras dan upaya peningkatan produktivitas dalam negeri tidak dapat memenuhi kebutuhan beras dalam negeri. Sehingga untuk menutupi kekurangan tersebut pemerintah mengambil keputusan untuk melakukan impor beras dari negara lain. Akan tetapi pada kenyataannya impor beras dilakukan ketika data statistik menunjukkan bahwa Indonesia sedang mengalami surplus beras. Penelitian ini bertujuan untuk mengetahui faktor-faktor apa saja yang mempengaruhi impor beras di Indonesia. Metode analisis yang digunakan adalah analisis regresi linier berganda dengan model Error Correction Model (ECM. Berdasarkan hasil penelitian disimpulkan bahwa secara parsial maupun secara bersama-sama produksi beras, konsumsi beras, harga beras dalam negeri dan nilai tukar rupiah terhadap dollar AS berpengaruh dan signifikan terhadap impor beras di Indonesia. Abstract ___________________________________________________________________ One of the government’s policy to fulfill the need of rice is to boost the domestic production. However, by increasing the population, the demand of rice will also increase and the effort of increasing the domestic productivity cannot supply domestic rice need. So, to cover the shortage the government make decision to import rice from other countries. Yet, in fact importing rice is occurred when the statistical data showed that the supply of rice in Indonesia is surplus. The purpose of this research is necessary to study the factors which influence the import of rice in Indonesia. The analysis method used is multiple linear regression analysis model with Error Correction Model (ECM. Based on the research proven that partially or jointly the production, the consumption, the
Variation of structural damping with response amplitude in piping systems
International Nuclear Information System (INIS)
Ware, A.G.
1986-01-01
From tests conducted over the last several years, it has become apparent that structural damping is not a single number applicable to all piping systems, but is highly dependent on piping system parameters such as supports, response amplitude, and insulation. As a result, there is considerable scatter in the available data. Furthermore, the relationships between the parameters and damping are often highly complex, interrelated, and difficult to predict. From tests of piping supported by various typical methods, two basic types of energy dissipation in the supports can be observed. The first is friction such as between spring hangers and their housings or in the internal mechanisms of constant force hangers. The second is impacting such as occurs in snubbers, rigid struts, and rod hangers. Overall, these effects lead to a wide variety of possibilities that can occur at low vibration levels and can change with only a slight perturbation of vibration amplitude. This can account for much of the scatter in the data at low strain levels. Thus damping is almost impossible to predict at low amplitudes, and extrapolation of this type data to higher amplitudes is cautioned. However, once strain levels rise above 100 to 200 micro in/in, the damping trend becomes easier to characterize. From the 100 to 200 micro in/in to 800 to 1000 micro in/in range the damping is fairly constant and is induced primarily by the supports. At the upper end of this range a threshold is reached in which damping increases with increasing strain amplitude. Data in the high strain (plastic range) is sparse since the test usually renders the pipe unsuitable for further use. 15 refs
Improving the Magnetic Damping of an AS-1 Seismometer
Marton, F.; Echreshzadeh, M.; Tokman, T. L.; Palaric, K. D.; Filippone, N. V.; Balzarette, M.; Sivo, J.
2016-12-01
Last year, students working on the SeismoSTEM project at Bergen Community College in New Jersey successfully manufactured and assembled an AS-1 seismometer1. For 2016, our objective has been to improve the magnetic damping mechanism invented by Chris Chapman2. As the mass on the boom is displaced by seismic waves, the spring will cause the mass to oscillate, therefore, damping is required. To achieve this, a paddle-shaped piece of copper, along with steel plates holding strong neodymium magnets are used. A localized eddy current is then induced, which then creates an opposing magnetic field. The challenges we faced for the summer internship was the fact that there was either too much or too little damping to distinguish the waves of an earthquake. However, we resolved the issue by designing our own prototype for moving the steel plates away and toward the copper paddle, to achieve critical damping. This was successfully completed by attaching two L-shaped pieces of aluminum, along with a cylindrical piece, to form a yoke. We then drilled a hole through the cylindrical piece and a plastic block for a bolt to slide through. Finally, the head of the bolt would then be used as a knob to shift the two plates away from and toward the paddle simultaneously. Although this was our solution for moving the plates horizontally, we also needed to find a way to lock the plates in place once we found the correct amount of damping. We accomplished this task by drilling two slotted holes on two symmetrical sheets of aluminum, which will allow us to slide the plates, and finally, lock them into place to avoid wobbling. References: 1Tokman, T.L. et al., What's shaking? Manufacturing & assembling an AS-1 educational seismometer for undergraduate stem research, Geological Society of America Abstracts with Programs. Vol. 47, No. 7, p.524, 2015. 2http://www.jclahr.com/science/psn/chapman/as1%20damping/
Quantitative analysis of the thermal damping of coherent axion oscillations
International Nuclear Information System (INIS)
Turner, M.S.
1985-01-01
Unruh and Wald have recently discussed a new mechanism for damping coherent axion oscillations, ''thermal damping,'' which occurs due to the temperature dependence of the axion mass and neutrino viscosity. We investigate the effect quantitatively and find that the present energy density in axions can be written as rho/sub a/ = rho/sub a0//(1+J/sub UW/), where rho/sub a/0 is what the axion energy density would be in the absence of the thermal-damping effect and J/sub UW/ is an integral whose integrand depends upon (dm/sub a//dT) 2 . As a function of f(equivalentPeccei-Quinn symmetry-breaking scale) J/sub UW/ achieves its maximum value for f/sub PQ/approx. =3 x 10 12 GeV; unless the axion mass turn-on is very sudden, Vertical Bar(T/m/sub a/)(dm/sub a//dT)Vertical Bar>>1, J/sub UW/ is <<1, implying that this damping mechanism is not significant
Damping rates of the SRRC storage ring
International Nuclear Information System (INIS)
Hsu, K.T.; Kuo, C.C.; Lau, W.K.; Weng, W.T.
1995-01-01
The SRRC storage ring is a low emittance synchrotron radiation machine with nominal operation energy 1.3 GeV. The design damping time due to synchrotron radiation is 10.7, 14.4, 8.7 ms for the horizontal, vertical and longitudinal plane, respectively. The authors measured the real machine damping time as a function of bunch current, chromaticity, etc. To damp the transverse beam instability, especially in the vertical plane, they need to increase chromaticity to large positive value. The damping rates are much larger than the design values. Landau damping contribution in the longitudinal plane is quite large, especially in the multibunch mode. The estimated synchrotron tune spread from the Landau damping is in agreement with the measured coherent longitudinal coupled bunch oscillation amplitude
Anisotropic damping of Timoshenko beam elements
Energy Technology Data Exchange (ETDEWEB)
Hansen, M.H.
2001-05-01
This report contains a description of a structural damping model for Timoshenko beam elements used in the aeroelastic code HawC developed at Risoe for modeling wind turbines. The model has been developed to enable modeling of turbine blades which often have different damping characteristics for flapwise, edgewise and torsional vibrations. The structural damping forces acting on the beam element are modeled by viscous damping described by an element damping matrix. The composition of this matrix is based on the element mass and stiffness matrices. It is shown how the coefficients for the mass and stiffness contributions can be calibrated to give the desired modal damping in the complete model of a blade. (au)
Fluid Damping Variation of a Slender Rod in Axial Flow Field
Energy Technology Data Exchange (ETDEWEB)
Park, Nam-Gyu; Yoo, Jong-Sung; Jung, Yil-Sup [KEPCO Nuclear Fuel Co., Daejeon (Korea, Republic of)
2016-10-15
This study proposed an analytic damping model considering the axial flow condition. In addition, the specific damping values with respect to the flow speeds are calculated. The flow induced damping is beneficial to fuel integrity in that impact energy due to severe accidents such as earthquake dissipates rapidly. A nuclear fuel bundle is composed of many slender fuel rods which contain fission material. The slender rod is typical structure in the fuel, therefore fluid damping estimation on the rod should be an important clue leading to fuel bundle damping identification. Severe accidents could cause fuel assembly vibration in the core, but large motion could be damped out rapidly when a strong damping mechanism is involved. This paper suggested a mathematical model of the slender structure. The physical meaning of the model is described, and the simulation results with the model are also provided. Actual damping due to the fluid is nonlinear, therefore further works are required to explain the detail behavior with the nonlinearity. The model validation test is on-going in KEPCO Nuclear Fuel, but it is believed that performance of the model is well correlated to the published work.
Measurements of long-range enhanced collisional velocity drag through plasma wave damping
Affolter, M.; Anderegg, F.; Dubin, D. H. E.; Driscoll, C. F.
2018-05-01
We present damping measurements of axial plasma waves in magnetized, multispecies ion plasmas. At high temperatures T ≳ 10-2 eV, collisionless Landau damping dominates, whereas, at lower temperatures T ≲ 10-2 eV, the damping arises from interspecies collisional drag, which is dependent on the plasma composition and scales roughly as T-3 /2 . This drag damping is proportional to the rate of parallel collisional slowing, and is found to exceed classical predictions of collisional drag damping by as much as an order of magnitude, but agrees with a new collision theory that includes long-range collisions. Centrifugal mass separation and collisional locking of the species occur at ultra-low temperatures T ≲ 10-3 eV, which reduce the drag damping from the T-3 /2 collisional scaling. These mechanisms are investigated by measuring the damping of higher frequency axial modes, and by measuring the damping in plasmas with a non-equilibrium species profile.
An Empirical Method for Particle Damping Design
Directory of Open Access Journals (Sweden)
Zhi Wei Xu
2004-01-01
Full Text Available Particle damping is an effective vibration suppression method. The purpose of this paper is to develop an empirical method for particle damping design based on extensive experiments on three structural objects – steel beam, bond arm and bond head stand. The relationships among several key parameters of structure/particles are obtained. Then the procedures with the use of particle damping are proposed to provide guidelines for practical applications. It is believed that the results presented in this paper would be helpful to effectively implement the particle damping for various structural systems for the purpose of vibration suppression.
Effect of milling on the damping behavior of nano-structured copper
Energy Technology Data Exchange (ETDEWEB)
Srikanth, Narasimalu; Thein, Maung Aye; Gupta, Manoj
2004-02-05
In the present study, elemental Cu powder was mechanically milled (MMed) for 10 h to reduce the grain (crystalline) size in the nano-range (<100 nm). The mechanically milled powder (10 h-MMed) and elemental powder without mechanical milling (MM) (0 h-MMed) was consolidated by die-cold compaction and were further hot extruded at different temperatures to maintain a crystallite size within the nano-range. Further, the specimen was tested by a novel free-free type suspended beam arrangement, coupled with circle-fit approach to determine damping characteristics. The characterization results help to understand the effect of the nano-size grains on the overall damping capacity of the bulk samples compared to a normal micro-crystalline sample. Results show that the damping capacity of the nano-grained material increases due to the presence of process induced microstructural changes similar to the damping behavior of a micro-grain sized specimen.
High Frequency Longitudinal Damped Vibrations of a Cylindrical Ultrasonic Transducer
Directory of Open Access Journals (Sweden)
Mihai Valentin Predoi
2014-01-01
Full Text Available Ultrasonic piezoelectric transducers used in classical nondestructive testing are producing in general longitudinal vibrations in the MHz range. A simple mechanical model of these transducers would be very useful for wave propagation numerical simulations, avoiding the existing complicated models in which the real components of the transducer are modeled by finite elements. The classical model for longitudinal vibrations is not adequate because the generated longitudinal wave is not dispersive, the velocity being the same at any frequency. We have adopted the Rayleigh-Bishop model, which avoids these limitations, even if it is not converging to the first but to the second exact longitudinal mode in an elastic rod, as obtained from the complicated Pochhammer-Chree equations. Since real transducers have significant vibrations damping, we have introduced a damping term in the Rayleigh-Bishop model, increasing the imaginary part and keeping almost identical real part of the wavenumber. Common transducers produce amplitude modulated signals, completely attenuated after several periods. This can be modeled by two close frequencies, producing a “beat” phenomenon, superposed on the high damping. For this reason, we introduce a two-rod Rayleigh-Bishop model with damping. Agreement with measured normal velocity on the transducer free surface is encouraging for continuation of the research.
Frequency and temperature dependence of high damping elastomers
International Nuclear Information System (INIS)
Kulak, R.F.; Hughes, T.H.
1993-01-01
High damping steel-laminated elastomeric seismic isolation bearings are one of the preferred devices for isolating large buildings and structures. In the US, the current reference design for the Advanced Liquid Metal Reactor (ALMR) uses laminated bearings for seismic isolation. These bearings are constructed from alternating layers of high damping rubber and steel plates. They are typically designed for shear strains between 50 and 100% and are expected to sustain two to three times these levels for beyond design basis loading conditions. Elastomeric bearings are currently designed to provide a system frequency between 0.4 and 0.8 Hz and expected to operate between -20 and 40 degrees Centigrade. To assure proper performance of isolation bearings, it is necessary to characterize the elastomer's response under expected variations of frequency and temperature. The dynamic response of the elastomer must be characterized within the frequency range that spans the bearing acceptance test frequency, which may be as low as 0.005 Hz, and the design frequency. Similarly, the variation in mechanical characteristics of the elastomer must be determined over the design temperature range, which is between -20 and 40 degrees Centigrade. This paper reports on (1) the capabilities of a testing facility at ANL for testing candidate elastomers, (2) the variation with frequency and temperature of the stiffness and damping of one candidate elastomer, and (3) the effect of these variations on bearing acceptance testing criteria and on the choice of bearing design values for stiffness and damping
Energy Technology Data Exchange (ETDEWEB)
Calderon-Guizar, J.G [Instituto de Investigaciones Electricas, Cuernavaca, Morelos (Mexico)]. E-mail: jgcg@iie.org.mx
2008-10-15
The presence of electromechanical oscillations in any electrical power system is a typical characteristic of this kind of systems. Provided the damping associated with these oscillations lies above of a minimum specified value, the occurrence of these oscillations is not considered as a threat to the system operation. This paper focuses the attention on the application of modal analysis for assessing the dynamical behavior of a power system subjected to small disturbances for different operating conditions and transmission system topologies, as well. The reported results indicate, that modal analysis enables a straight identification of the causes that contribute negatively to the damping of the electromechanical modes. [Spanish] La presencia de oscilaciones electromecanicas en cualquier Sistema Electrico de Potencia (SEP) es una caracteristica propia de estos sistemas. Mientras el amortiguamiento asociado con este tipo de oscilaciones se encuentre dentro de los limites considerados como aceptables para la operacion continua de este tipo de sistemas, el surgimiento de estas no se considera una amenaza para la operacion segura del SEP. El presente articulo, centra su atencion en la aplicacion del analisis modal para evaluar el comportamiento dinamico de un SEP ante la ocurrencia de disturbios de magnitud pequena para diferentes topologias y condiciones de operacion. Los resultados reportados indican, que la aplicacion del analisis modal permite la identificacion directa de las causas que contribuyen en forma negativa al amortiguamiento asociado con los modos electromecanicos, asi como la ubicacion mas adecuada de controles que contribuyan a mejorar el amortiguamiento de los mismos.
Directory of Open Access Journals (Sweden)
A. H. A. Pereira
2010-07-01
Full Text Available Resistance to thermal shock damage is an important characteristic in refractory materials, since it determines their performance and service life in many applications. Therefore, the use of more sensitive techniques is desirable to improve the evaluation of thermal shock damage and monitoring of nucleation and propagation cracks and microcracks.The aim of this work was to evaluate the potential of damping change characterization to quantify thermal shock damage and to estimate the retained mechanical strength in complement to the dynamic Young's modulus test. Variations in damping and retained Young's modulus and their correlation with the mechanical strength of a high alumina refractory castable were evaluated at different thermal shock temperatures and number of cycles. The changes in damping were proportional to the retained mechanical strength, similarly to the retained Young's modulus. Changes in damping were also detected which were not indicated by the Young's modulus measurements.A resistência ao dano por choque térmico é uma característica importante dos materiais refratários visto que determina o desempenho e vida útil destes materiais em várias aplicações. Portanto é desejável a aplicação de técnicas mais sensíveis para avaliação do dano por choque térmico e monitoração da nucleação e expansão de trincas e microtrincas. O objetivo deste trabalho foi avaliar o potencial da caracterização da variação do amortecimento para quantificar o dano por choque térmico e para estimar o módulo de ruptura retido, complementarmente à caracterização do módulo de Young dinâmico. Foram estudadas as variações do amortecimento, do módulo de Young retido e a correlação destas variações com a resistência mecânica de um concreto refratário de alta alumina para distintas variações de temperatura e número de ciclos. As alterações encontradas no amortecimento foram proporcionais à resistência mecânica retida
Damped oscillations of linear systems a mathematical introduction
Veselić, Krešimir
2011-01-01
The theory of linear damped oscillations was originally developed more than hundred years ago and is still of vital research interest to engineers, mathematicians and physicists alike. This theory plays a central role in explaining the stability of mechanical structures in civil engineering, but it also has applications in other fields such as electrical network systems and quantum mechanics. This volume gives an introduction to linear finite dimensional damped systems as they are viewed by an applied mathematician. After a short overview of the physical principles leading to the linear system model, a largely self-contained mathematical theory for this model is presented. This includes the geometry of the underlying indefinite metric space, spectral theory of J-symmetric matrices and the associated quadratic eigenvalue problem. Particular attention is paid to the sensitivity issues which influence numerical computations. Finally, several recent research developments are included, e.g. Lyapunov stability and ...
Damping-off in forest nurseries
Carl Hartley
1921-01-01
Damping-off is the commonest English name for a symptomatic group of diseases affecting great numbers of plant species of widely separated phylogenetic groups. It is commonly used for any disease which results in the rapid decay of young succulent seedlings or soft cuttings. Young shoots from underground rootstocks may also be damped-off before they break through the...
Beam dynamic issues in TESLA damping ring
International Nuclear Information System (INIS)
Shiltsev, V.
1996-05-01
In this paper we study general requirements on impedances of the linear collider TESLA damping ring design. Quantitative consideration is performed for 17-km long ''dog-bone'' ring. Beam dynamics in alternative options of 6.3 and 2.3-km long damping rings is briefly discussed. 5 refs., 2 tabs
On Collisionless Damping of Ion Acoustic Waves
DEFF Research Database (Denmark)
Jensen, Vagn Orla; Petersen, P.I.
1973-01-01
Exact theoretical treatments show that the damping of ion acoustic waves in collisionless plasmas does not vanish when the derivative of the undisturbed distribution function at the phase velocity equals zero.......Exact theoretical treatments show that the damping of ion acoustic waves in collisionless plasmas does not vanish when the derivative of the undisturbed distribution function at the phase velocity equals zero....
Study for ILC Damping Ring at KEKB
Energy Technology Data Exchange (ETDEWEB)
Flanagan, J.W.; Fukuma, H.; Kanazawa, K.I.; Koiso, H.; Masuzawa, M.; Ohmi, Kazuhito; Ohnishi, Y.; Oide, Katsunobu; Suetsugu, Y.; Tobiyama, M.; /KEK, Tsukuba; Pivi, M.; /SLAC
2011-11-04
ILC damping ring consists of very low emittance electron and positron storage rings. It is necessary for ILC damping ring to study electron cloud effects in such low emittance positron ring. We propose a low emittance operation of KEKB to study the effects.
Swing damped movement of suspended objects
International Nuclear Information System (INIS)
Jones, J.F.; Petterson, B.J.; Werner, J.C.
1990-01-01
Transportation of large objects such as nuclear waste shipping casks using overhead cranes can induce pendular motion of the object. Residual oscillation from transportation typically must be damped or allowed to decay before the next process can take place. By properly programming the acceleration of the transporting device (e.g., crane) an oscillation damped transport and swing free stop are obtainable. This report reviews the theory associated with formulating such oscillation damped trajectories for a simply suspended object (e.g., simple pendulum). In addition, the use of force servo damping to eliminate initial oscillation of simply suspended objects is discussed. This is often needed to provide a well defined initial state for the system prior to executing an oscillation damped move. Also included are descriptions of experiments using a CIMCORP XR6100 gantry robot and results from these experiments. Finally, sources of error resulting in small residual oscillations are identified and possible solutions presented
Satellite Dynamic Damping via Active Force Control Augmentation
Varatharajoo, Renuganth
2012-07-01
An approach that incorporates the Active Force Control (AFC) technique into a conventional Proportional-Derivative (PD) controller is proposed for a satellite active dynamic damping towards a full attitude control. The AFC method has been established to facilitate a robust motion control of dynamical systems in the presence of disturbances, parametric uncertainties and changes that are commonly prevalent in the real-world environment. The usefulness of the method can be extended by introducing intelligent mechanisms to approximate the mass or inertia matrix of the dynamic system to trigger the compensation effect of the controller. AFC is a technique that relies on the appropriate estimation of the inertial or mass parameters of the dynamic system and the measurements of the acceleration and force signals induced by the system if practical implementation is ever considered. In AFC, it is shown that the system subjected to a number of disturbances remains stable and robust via the compensating action of the control strategy. We demonstrate that it is possible to design a spacecraft attitude feedback controller that will ensure the system dynamics set point remains unchanged even in the presence of the disturbances provided that the actual disturbances can be modeled effectively. In order to further facilitate this analysis, a combined energy and attitude control system (CEACS) is proposed as a model satellite attitude control actuator. All the governing equations are established and the proposed satellite attitude control architecture is made amenable to numerical treatments. The results show that the PD-AFC attitude damping performances are superiorly better than that of the solely PD type. It is also shown that the tunings of the AFC system gains are crucial to ensure a better attitude damping performance and this process is mandatory for AFC systems. Finally, the results demonstrate an important satellite dynamic damping enhancement capability using the AFC
Optimization of SMA layers in composite structures to enhance damping
Haghdoust, P.; Cinquemani, S.; Lecis, N.; Bassani, P.
2016-04-01
The performance of lightweight structures can be severely affected by vibration. New design concepts leading to lightweight, slender structural components can increase the vulnerability of the components to failure due to excessive vibration. The intelligent approach to address the problem would be the use of materials which are more capable in dissipating the energy due to their high value of loss factor. Among the different materials available to achieve damping, much attention has been attached to the use of shape memory alloys (SMAs) because of their unique microstructure, leading to good damping capacity. This work describes the design and optimization of a hybrid layered composite structure for the passive suppression of flexural vibrations in slender and light structures. Embedding the SMA layers in composite structure allows to combine different properties: the lightness of the base composite (e.g. fiber glass), the mechanical strength of the insert of metallic material and the relevant damping properties of SMA, in the martensitic phase. In particular, we put our attention on embedding the CuZnAl in the form of thin sheet in a layered composite made by glass fiber reinforced epoxy. By appropriately positioning of the SMA sheets so that they are subjected to the maximum curvature, the damping of the hybrid system can be considerably enhanced. Accordingly analytical method for evaluating the energy dissipation of the thin sheets with different shapes and patterns is developed and is followed by a shape optimization based on genetic algorithm. Eventually different configurations of the hybrid beam structure with different patterns of SMA layer are proposed and compared in the term of damping capacity.
Analytical Solution and Physics of a Propellant Damping Device
Yang, H. Q.; Peugeot, John
2011-01-01
NASA design teams have been investigating options for "detuning" Ares I to prevent oscillations originating in the vehicle solid-rocket main stage from synching up with the natural resonance of the rest of the vehicle. An experimental work started at NASA MSFC center in 2008 using a damping device showed great promise in damping the vibration level of an 8 resonant tank. However, the mechanisms of the vibration damping were not well understood and there were many unknowns such as the physics, scalability, technology readiness level (TRL), and applicability for the Ares I vehicle. The objectives of this study are to understand the physics of intriguing slosh damping observed in the experiments, to further validate a Computational Fluid Dynamics (CFD) software in propellant sloshing against experiments with water, and to study the applicability and efficiency of the slosh damper to a full scale propellant tank and to cryogenic fluids. First a 2D fluid-structure interaction model is built to model the system resonance of liquid sloshing and structure vibration. A damper is then added into the above model to simulate experimentally observed system damping phenomena. Qualitative agreement is found. An analytical solution is then derived from the Newtonian dynamics for the thrust oscillation damper frequency, and a slave mass concept is introduced in deriving the damper and tank interaction dynamics. The paper will elucidate the fundamental physics behind the LOX damper success from the derivation of the above analytical equation of the lumped Newtonian dynamics. Discussion of simulation results using high fidelity multi-phase, multi-physics, fully coupled CFD structure interaction model will show why the LOX damper is unique and superior compared to other proposed mitigation techniques.
Overview on methods for formulating explicit damping matrices for non-classically damped structures
International Nuclear Information System (INIS)
Xu, J.
1998-04-01
In computing the dynamic response of a connected system with multiple components having dissimilar damping characteristics, which is often referred to as nonclassically damped system such as nuclear power plant piping systems supported by stiff structures, one needs to define the system-level damping based upon the damping information of components. This is frequently done in practice using approximate methods expressed as composite modal damping with weighting functions. However, when the difference in damping among components is substantial, the composite modal damping may become inappropriate in the characterization of the damping behavior of such systems. In recent years, several new methods have emerged with the expectation that they could produce more exact system-level damping for a group of nonclassically damped structures which are comprised of components that possess classical modal damping. In this paper, an overview is presented to examine these methods in the light of their theoretical basis, the technical merits, and practical applications. To this end, a synthesis method is described, which was shown to reduce to the other methods in the literature
International Nuclear Information System (INIS)
Minary-Jolandan, Majid; Yu Minfeng
2008-01-01
An improved approach is introduced in damping measurement with atomic force microscope (AFM) for the in situ measurement of the offset phase shift needed for determining the intrinsic mechanical damping in nanoscale materials. The offset phase shift is defined and measured at a point of zero contact force according to the deflection part of the AFM force plot. It is shown that such defined offset phase shift is independent of the type of sample material, varied from hard to relatively soft materials in this study. This improved approach allows the self-calibrated and quantitative damping measurement with AFM. The ability of dynamic mechanical analysis for the measurement of damping in isolated one-dimensional nanostructures, e.g. individual multiwalled carbon nanotubes, was demonstrated
Analisis Value Chain Di Industri Otomotif
Hendri, Hendri
2017-01-01
Penelitian ini untuk menganalisis industri otomotif. Tujuan dari penelitian ini adalah untuk menganalisis dan mengetahui aktivitas dan kondisi internal proses industri manufaktur dengan menggunakan value chain guna masukan dimasa akan datang bagi industri otomotif secara khusus. Value Chain merupakan rantai nilai yang dapat mengetahui kekuatan Perusahaan, keuntungan dan kesuksesan dari rantai aktivitas dalam Perusahaan atau industri manufaktur.Metode analisis menggunakan Statistika Deskript...
Performance analysis of conventional PSS and fuzzy controller for damping power system oscillations
Banna, Hasan UI; Luna Alloza, Álvaro; Rodríguez Cortés, Pedro; Cabrera Tobar, Ana; Ghorbani, Hamidreza; Ying, Shaoqing
2014-01-01
Electro-mechanical oscillations are produced, in the machines of an interconnected power network, followed by a disturbance or due to high power transfer through weak tie lines. These oscillations should be damped as quickly as possible to ensure the reliable and stable operation of the network. To damp these oscillations different controllers, based on local or wide area signals, have been the subject of many papers. This paper presents the analysis of the performance of Conventional Power S...
ANALISIS KESELAMATAN TERMOHIDROLIK BULK SHIELDING REAKTOR KARTINI
Directory of Open Access Journals (Sweden)
Azizul Khakim
2015-10-01
Full Text Available ABSTRAK ANALISIS KESELAMATAN TERMOHIDROLIK BULK SHIELDING REAKTOR KARTINI. Bulk shielding merupakan fasilitas yang terintegrasi dengan reaktor Kartini yang berfungsi sebagai penyimpanan sementara bahan bakar bekas. Fasilitas ini merupakan fasilitas yang termasuk dalam struktur, sistem dan komponen (SSK yang penting bagi keselamatan. Salah satu fungsi keselamatan dari sistem penanganan dan penyimpanan bahan bakar adalah mencegah kecelakaan kekritisan yang tak terkendali dan membatasi naiknya temperatur bahan bakar. Analisis keselamatan paling kurang harus mencakup analisis keselamatan dari sisi neutronik dan termo hidrolik Bulk shielding. Analisis termo hidrolik ditujukan untuk memastikan perpindahan panas dan proses pendinginan bahan bakar bekas berjalan baik dan tidak terjadi akumulasi panas yang mengancam integritas bahan bakar. Code tervalidasi PARET/ANL digunakan untuk analisis pendinginan dengan mode konveksi alam. Hasil perhitungan menunjukkan bahwa mode pendinginan konvekasi alam cukup memadai dalam mendinginkan panas sisa tanpa mengakibatkan kenaikan temperatur bahan bakar yang signifikan. Kata kunci: Bulk shielding, bahan bakar bekas, konveksi alam, PARET. ABSTRACT THERMAL HYDRAULIC SAFETY ANALYSIS OF BULK SHIELDING KARTINI REACTOR. Bulk shielding is an integrated facility to Kartini reactor which is used for temporary spent fuels storage. The facility is one of the structures, systems and components (SSCs important to safety. Among the safety functions of fuel handling and storage are to prevent any uncontrolable criticality accidents and to limit the fuel temperature increase. Safety analyses should, at least, cover neutronic and thermal hydraulic calculations of the bulk shielding. Thermal hydraulic analyses were intended to ensure that heat removal and the process of the spent fuels cooling takes place adequately and no heat accumulation that challenges the fuel integrity. Validated code, PARET/ANL was used for analysing the
International Nuclear Information System (INIS)
Wang, Xueqin; Pei, Yanling; Ma, Yue
2013-01-01
Samples with various interface microstructures between the coating and the substrate were designed and fabricated in this paper. Dynamic mechanical thermal analyzer (DMTA) was utilized to investigate the dynamic mechanical properties of the samples and scanning electron microscopy (SEM) was used to observe the interface microstructure between the substrate and coating. The effect of the interface microstructure on damping was studied, and results indicated that the larger the coating/substrate interface thickness was and the more interface defects were, the higher interface system damping was. When the micro-hardness ratio of substrate to coating was increased, the damping of coating system was enhanced. The effect of the APS and EB-PVD coating on damping capacity was investigated. There was a dramatic increase in the damping value of the APS coating when the strain was higher than 20 ppm, while the damping amplitude effect of the EB-PVD coating was not so obvious, which could mainly be caused by the different energy dissipation mechanisms of the two coatings.
Lifetime measurement of ATF damping ring
International Nuclear Information System (INIS)
Okugi, T.; Hayano, H.; Kubo, K.; Naito, T.; Terunuma, N.; Urakawa, J.; Zimmermann, F.
1998-06-01
The purpose of the ATF damping ring is the development of technologies for producing a low emittance beam required in future linear colliders such as JLC. The lifetime of the damping ring is very short (typically a few minutes). It is limited by elastic beam-gas scattering along with a small dynamic aperture, and by single intra-beam scattering (Touschek effect). The Touschek lifetime strongly depends upon the charge density of the beam, especially, the size of the vertical emittance. In this paper, the authors report the results of beam lifetime measurements in the ATF damping ring and the estimation of the vertical emittance from these measurements
A Resonant Damping Study Using Piezoelectric Materials
Min, J. B.; Duffy, K. P.; Choi, B. B.; Morrison, C. R.; Jansen, R. H.; Provenza, A. J.
2008-01-01
Excessive vibration of turbomachinery blades causes high cycle fatigue (HCF) problems requiring damping treatments to mitigate vibration levels. Based on the technical challenges and requirements learned from previous turbomachinery blade research, a feasibility study of resonant damping control using shunted piezoelectric patches with passive and active control techniques has been conducted on cantilever beam specimens. Test results for the passive damping circuit show that the optimum resistive shunt circuit reduces the third bending resonant vibration by almost 50%, and the optimum inductive circuit reduces the vibration by 90%. In a separate test, active control reduced vibration by approximately 98%.
Nonlinear effects in the damping of third-sound pulses
International Nuclear Information System (INIS)
Browne, D.A.
1984-01-01
We show that nonlinearities in the equations of motion for a third-sound pulse in a thick superfluid film lead to the production of short-wavelength solitons. The soliton damping arises from viscous stresses in the film, rather than from coupling to thermal currents in the vapor and the substrate as in the hydrodynamic regime. These solitons are more strongly damped than a long-wavelength third-sound wave and lead to a larger attenuation of the pulse. We show that this mechanism can account for the discrepancy between attenuation calculated theoretically for the long-wavelength limit and the experimentally observed attenuation of low-amplitude third-sound pulses
Ambient-temperature high damping capacity in TiPd-based martensitic alloys
Energy Technology Data Exchange (ETDEWEB)
Xue, Dezhen [Multi-disciplinary Materials Research Center, Frontier Institute of Science and Technology, State Key Laboratory for Mechanical Behavior of Materials, Xi' an Jiaotong University, Xi' an 710049 (China); Theoretical Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Zhou, Yumei, E-mail: zhouyumei@mail.xjtu.edu.cn [Multi-disciplinary Materials Research Center, Frontier Institute of Science and Technology, State Key Laboratory for Mechanical Behavior of Materials, Xi' an Jiaotong University, Xi' an 710049 (China); Ding, Xiangdong [Multi-disciplinary Materials Research Center, Frontier Institute of Science and Technology, State Key Laboratory for Mechanical Behavior of Materials, Xi' an Jiaotong University, Xi' an 710049 (China); Otsuka, Kazuhiro [Ferroic Physics Group, National Institute for Materials Science, Tsukuba 305-0047, Ibaraki (Japan); Lookman, Turab [Theoretical Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Sun, Jun [Multi-disciplinary Materials Research Center, Frontier Institute of Science and Technology, State Key Laboratory for Mechanical Behavior of Materials, Xi' an Jiaotong University, Xi' an 710049 (China); Ren, Xiaobing [Multi-disciplinary Materials Research Center, Frontier Institute of Science and Technology, State Key Laboratory for Mechanical Behavior of Materials, Xi' an Jiaotong University, Xi' an 710049 (China); Ferroic Physics Group, National Institute for Materials Science, Tsukuba 305-0047, Ibaraki (Japan)
2015-04-24
Shape memory alloys (SMAs) have attracted considerable attention for their high damping capacities. Here we investigate the damping behavior of Ti{sub 50}(Pd{sub 50−x}D{sub x}) SMAs (D=Fe, Co, Mn, V) by dynamic mechanical analysis. We find that these alloys show remarkably similar damping behavior. There exists a sharp damping peak associated with the B2–B19 martensitic transformation and a high damping plateau (Q{sup −1}~0.02–0.05) over a wide ambient-temperature range (220–420 K) due to the hysteretic twin boundary motion. After doping hydrogen into the above alloys, a new relaxation-type damping peak appears in the martensite phase over 270–360 K. Such a peak is considered to originate from the interaction of hydrogen atoms with twin boundaries and the corresponding damping capacity (Q{sup −1}~0.05–0.09) is enhanced by roughly twice that of the damping plateau for each alloy. Moreover, the relaxation peaks are at higher temperatures for the TiPd-based alloys (270–370 K) than for the TiNi-based alloys (190–260 K). We discuss the influence of hydrogen diffusion, mobility of twin boundaries and hydrogen–twin boundary interaction on the temperature range of the relaxation peak. Our results suggest that a martensite, with appropriate values for twinning shear and hydrogen doping level, provides a route towards developing high damping SMAs for applications in desired temperature ranges.
Power system damping - Structural aspects of controlling active power
Energy Technology Data Exchange (ETDEWEB)
Samuelsson, O.
1997-04-01
Environmental and economical aspects make it difficult to build new power lines and to reinforce existing ones. The continued growth in demand for electric power must therefore to a great extent be met by increased loading of available lines. A consequence is that power system damping is reduced, leading to a risk of poorly damped power oscillations between the generators. This thesis proposes the use of controlled active loads to increase damping of such electro-mechanical oscillations. The focus is on structural aspects of controller interaction and of sensor and actuator placement. On-off control based on machine frequency in a single machine infinite bus system is analysed using energy function analysis and phase plane plots. An on-off controller with estimated machine frequency as input has been implemented. At a field test it damped oscillations of a 0.9 MW hydro power generator by controlling a 20kW load. The linear analysis uses two power system models with three and twenty-three machines respectively. Each damper has active power as output and local bus frequency or machine frequency as input. The power system simulator EUROSTAG is used both for generation of the linearized models and for time simulations. Measures of active power mode controllability and phase angle mode observability are obtained from the eigenvectors of the differential-algebraic models. The geographical variation in the network of these quantities is illustrated using the resemblance to bending modes of flexible mechanical structures. Eigenvalue sensitivities are used to determine suitable damper locations. A spring-mass equivalent to an inter-area mode provides analytical expressions, that together with the concept of impedance matching explain the structural behaviour of the power systems. For large gains this is investigated using root locus plots. 64 refs, 99 figs, 20 tabs
Yang, H. Q.; West, Jeff
2016-01-01
Determination of slosh damping is a very challenging task as there is no analytical solution. The damping physics involves the vorticity dissipation which requires the full solution of the nonlinear Navier-Stokes equations. As a result, previous investigations were mainly carried out by extensive experiments. A systematical study is needed to understand the damping physics of baffled tanks, to identify the difference between the empirical Miles equation and experimental measurements, and to develop new semi-empirical relations to better represent the real damping physics. The approach of this study is to use Computational Fluid Dynamics (CFD) technology to shed light on the damping mechanisms of a baffled tank. First, a 1-D Navier-Stokes equation representing different length scales and time scales in the baffle damping physics is developed and analyzed. Loci-STREAM-VOF, a well validated CFD solver developed at NASA MSFC, is applied to study the vorticity field around a baffle and around the fluid-gas interface to highlight the dissipation mechanisms at different slosh amplitudes. Previous measurement data is then used to validate the CFD damping results. The study found several critical parameters controlling fluid damping from a baffle: local slosh amplitude to baffle thickness (A/t), surface liquid depth to tank radius (d/R), local slosh amplitude to baffle width (A/W); and non-dimensional slosh frequency. The simulation highlights three significant damping regimes where different mechanisms dominate. The study proves that the previously found discrepancies between Miles equation and experimental measurement are not due to the measurement scatter, but rather due to different damping mechanisms at various slosh amplitudes. The limitations on the use of Miles equation are discussed based on the flow regime.
Power Oscillation Damping from VSC-HVDC Connected Offshore Wind Power Plants
DEFF Research Database (Denmark)
Zeni, Lorenzo; Eriksson, Robert; Goumalatsos, Spyridon
2016-01-01
The implementation of power oscillation damping service on offshore wind power plants connected to onshore grids by voltage-source-converter-based high voltage direct current transmission is discussed. Novel design guidelines for damping controllers on voltage-source converters and wind power plant...... regarding real wind power plants are discussed: 1) robustness against control/communication delays; 2) limitations due to mechanical resonances in wind turbine generators; 3) actual capability of wind power plants to provide damping without curtailing production; and 4) power-ramp rate limiters....... controllers are derived, using phasor diagrams and a test network model and are then verified on a generic power system model. The effect of voltage regulators is analyzed, which is important for selecting the most robust damping strategy. Furthermore, other often disregarded practical implementation aspects...
Directory of Open Access Journals (Sweden)
Chaowu Jin
2016-01-01
Full Text Available At present, the stiffness and damping identification for active magnetic bearings (AMBs are still in the stage of theoretical analysis. The theoretical analysis indicates that if the mechanical structure and system parameters are determined, AMBs stiffness and damping are only related to frequency characteristic of control system, ignoring operating condition. More importantly, few verification methods are proposed. Considering the shortcomings of the theoretical identification, this paper obtains these coefficients from the experiment by using the magnetic bearing as a sine exciter. The identification results show that AMBs stiffness and damping have a great relationship with the control system and rotating speed. Specifically, at low rotating speed, the stiffness and damping can be obtained from the rotor static suspension by adding the same excitation frequency. However, at high speed, different from the static suspension situation, the AMBs supporting coefficients are not only related to the frequency characteristics of control system, but also related to the system operating conditions.
Damping of electron center-of-mass oscillation in ultracold plasmas
International Nuclear Information System (INIS)
Chen, Wei-Ting; Witte, Craig; Roberts, Jacob L.
2016-01-01
Applying a short electric field pulse to an ultracold plasma induces an electron plasma oscillation. This manifests itself as an oscillation of the electron center of mass around the ion center of mass in the ultracold plasma. In general, the oscillation can damp due to either collisionless or collisional mechanisms, or a combination of the both. To investigate the nature of oscillation damping in ultracold plasmas, we developed a molecular dynamics model of the ultracold plasma electrons. Through this model, we found that depending on the neutrality of the ultracold plasma and the size of an applied DC electric field, there are some parameter ranges where the damping is primarily collisional and some primarily collisionless. We conducted experiments to compare the measured damping rate with theory predictions and found them to be in good agreement. Extension of our measurements to different parameter ranges should enable studies for strong-coupling influence on electron-ion collision rates.
Numerical design and test on an assembled structure of a bolted joint with viscoelastic damping
Hammami, Chaima; Balmes, Etienne; Guskov, Mikhail
2016-03-01
Mechanical assemblies are subjected to many dynamic loads and modifications are often needed to achieve acceptable vibration levels. While modifications on mass and stiffness are well mastered, damping modifications are still considered difficult to design. The paper presents a case study on the design of a bolted connection containing a viscoelastic damping layer. The notion of junction coupling level is introduced to ensure that sufficient energy is present in the joints to allow damping. Static performance is then addressed and it is shown that localization of metallic contact can be used to meet objectives, while allowing the presence of viscoelastic materials. Numerical prediction of damping then illustrates difficulties in optimizing for robustness. Modal test results of three configurations of an assembled structure, inspired by aeronautic fuselages, are then compared to analyze the performance of the design. While validity of the approach is confirmed, the effect of geometric imperfections is shown and stresses the need for robust design.
Coupled oscillators in identification of nonlinear damping of a real parametric pendulum
Olejnik, Paweł; Awrejcewicz, Jan
2018-01-01
A damped parametric pendulum with friction is identified twice by means of its precise and imprecise mathematical model. A laboratory test stand designed for experimental investigations of nonlinear effects determined by a viscous resistance and the stick-slip phenomenon serves as the model mechanical system. An influence of accurateness of mathematical modeling on the time variability of the nonlinear damping coefficient of the oscillator is proved. A free decay response of a precisely and imprecisely modeled physical pendulum is dependent on two different time-varying coefficients of damping. The coefficients of the analyzed parametric oscillator are identified with the use of a new semi-empirical method based on a coupled oscillators approach, utilizing the fractional order derivative of the discrete measurement series treated as an input to the numerical model. Results of application of the proposed method of identification of the nonlinear coefficients of the damped parametric oscillator have been illustrated and extensively discussed.
Offline software for the DAMPE experiment
Wang, Chi; Liu, Dong; Wei, Yifeng; Zhang, Zhiyong; Zhang, Yunlong; Wang, Xiaolian; Xu, Zizong; Huang, Guangshun; Tykhonov, Andrii; Wu, Xin; Zang, Jingjing; Liu, Yang; Jiang, Wei; Wen, Sicheng; Wu, Jian; Chang, Jin
2017-10-01
A software system has been developed for the DArk Matter Particle Explorer (DAMPE) mission, a satellite-based experiment. The DAMPE software is mainly written in C++ and steered using a Python script. This article presents an overview of the DAMPE offline software, including the major architecture design and specific implementation for simulation, calibration and reconstruction. The whole system has been successfully applied to DAMPE data analysis. Some results obtained using the system, from simulation and beam test experiments, are presented. Supported by Chinese 973 Program (2010CB833002), the Strategic Priority Research Program on Space Science of the Chinese Academy of Science (CAS) (XDA04040202-4), the Joint Research Fund in Astronomy under cooperative agreement between the National Natural Science Foundation of China (NSFC) and CAS (U1531126) and 100 Talents Program of the Chinese Academy of Science
Simplified Model of Nonlinear Landau Damping
International Nuclear Information System (INIS)
Yampolsky, N.A.; Fisch, N.J.
2009-01-01
The nonlinear interaction of a plasma wave with resonant electrons results in a plateau in the electron distribution function close to the phase velocity of the plasma wave. As a result, Landau damping of the plasma wave vanishes and the resonant frequency of the plasma wave downshifts. However, this simple picture is invalid when the external driving force changes the plasma wave fast enough so that the plateau cannot be fully developed. A new model to describe amplification of the plasma wave including the saturation of Landau damping and the nonlinear frequency shift is proposed. The proposed model takes into account the change of the plasma wave amplitude and describes saturation of the Landau damping rate in terms of a single fluid equation, which simplifies the description of the inherently kinetic nature of Landau damping. A proposed fluid model, incorporating these simplifications, is verified numerically using a kinetic Vlasov code.
Electron beam depolarization in a damping ring
International Nuclear Information System (INIS)
Minty, M.
1993-04-01
Depolarization of a polarized electron beam injected into a damping ring is analyzed by extending calculations conventionally applied to proton synchrotrons. Synchrotron radiation in an electron ring gives rise to both polarizing and depolarizing effects. In a damping ring, the beam is stored for a time much less than the time for self polarization. Spin flip radiation may therefore be neglected. Synchrotron radiation without spin flips, however, must be considered as the resonance strength depends on the vertical betatron oscillation amplitude which changes as the electron beam is radiation damped. An expression for the beam polarization at extraction is derived which takes into account radiation damping. The results are applied to the electron ring at the Stanford Linear Collider and are compared with numerical matrix formalisms
Damping Wiggler Study at KEK-ATF
Naito, Takashi; Honda, Yosuke; Korostelev, Maxim S; Kubo, Kiyoshi; Kuriki, Masao; Kuroda, Shigeru; Muto, Toshiya; Nakamura, Norio; Ross, Marc; Sakai, Hiroshi; Terunuma, Nobuhiro; Urakawa, Junji; Zimmermann, Frank
2005-01-01
The effects by damping wiggler magnets have been studied at KEK-ATF. The damping ring of the KEK-ATF is a 1.3 GeV storage ring capable of producing ultra-low emittance electron beams. It is significant issue to realize fast damping in the damping ring. The tuning method with 4 sets of wiggler was investigated for the ultra-low emittance beam. The performance on the beam quality, which is related to the transverse (x and y) and the longitudinal (z and dp/p), has been measured by the SR monitor, the laser wire, the streak camera and the energy spread monitor at the extraction line. We report on the operation condition and the measurement results.
Damping of type III solar radio bursts
International Nuclear Information System (INIS)
Levin, B.N.
1982-01-01
The meter- and decameter-wavelength damping of type III bursts may be attributable to stabilization of the Langmuir-wave instability of the fast-electron streams through excitation of cyclotron-branch plasma waves
Radiation damping and decoherence in quantum electrodynamics
International Nuclear Information System (INIS)
Breuer, H.P.
2000-01-01
The processes of radiation damping and decoherence in quantum electrodynamics are studied from an open system's point of view. Employing functional techniques of field theory, the degrees of freedom of the radiation field are eliminated to obtain the influence phase functional which describes the reduced dynamics of the matter variables. The general theory is applied to the dynamics of a single electron in the radiation field. From a study of the wave packet dynamics a quantitative measure for the degree of decoherence, the decoherence function, is deduced. The latter is shown to describe the emergence of decoherence through the emission of bremsstrahlung caused by the relative motion of interfering wave packets. It is argued that this mechanism is the most fundamental process in quantum electrodynamics leading to the destruction of coherence, since it dominates for short times and because it is at work even in the electromagnetic field vacuum at zero temperature. It turns out that decoherence trough bremsstrahlung is very small for single electrons but extremely large for superpositions of many-particle states. (orig.)
Proceedings of Damping Volume 1 of 3
1993-06-01
paper. This work will present a passive piezoelectric damping implementation on ASTREX, a large space structure. The motivation behind this research is...Presented at Damping San Francisco, CA February 24-26, 1993 Motivation "• Accurate design of precision structures "* Computer modelling - Design...14) (KI f(0)/Fl,.) FRom equations (3) and (6), Young’s modulus of rubber specimen is written as; L Ea-K (15) A E - EJ(I+ PS4 ) (16) NONRESONANT TEST
Quantum damped oscillator I: Dissipation and resonances
International Nuclear Information System (INIS)
Chruscinski, Dariusz; Jurkowski, Jacek
2006-01-01
Quantization of a damped harmonic oscillator leads to so called Bateman's dual system. The corresponding Bateman's Hamiltonian, being a self-adjoint operator, displays the discrete family of complex eigenvalues. We show that they correspond to the poles of energy eigenvectors and the corresponding resolvent operator when continued to the complex energy plane. Therefore, the corresponding generalized eigenvectors may be interpreted as resonant states which are responsible for the irreversible quantum dynamics of a damped harmonic oscillator
International Nuclear Information System (INIS)
Edme, R.
1983-01-01
If a dynamic response analysis (harmonic excitation) is carried out with the modal method, the modal damping coefficients must be approximated to match the structural damping. The program ASKA-Damping, which also supplies an error assessment of the approximation, was developed for this purpose. The modal method and the direct method are applied to a test example and their results compared. It is suggested that the ASKA manufacturers extend the spectral earthquake response analysis to take these modal damping coefficients into account so that the results become less conservative. (orig.) [de
Bryan's effect and anisotropic nonlinear damping
Joubert, Stephan V.; Shatalov, Michael Y.; Fay, Temple H.; Manzhirov, Alexander V.
2018-03-01
In 1890, G. H. Bryan discovered the following: "The vibration pattern of a revolving cylinder or bell revolves at a rate proportional to the inertial rotation rate of the cylinder or bell." We call this phenomenon Bryan's law or Bryan's effect. It is well known that any imperfections in a vibratory gyroscope (VG) affect Bryan's law and this affects the accuracy of the VG. Consequently, in this paper, we assume that all such imperfections are either minimised or eliminated by some known control method and that only damping is present within the VG. If the damping is isotropic (linear or nonlinear), then it has been recently demonstrated in this journal, using symbolic analysis, that Bryan's law remains invariant. However, it is known that linear anisotropic damping does affect Bryan's law. In this paper, we generalise Rayleigh's dissipation function so that anisotropic nonlinear damping may be introduced into the equations of motion. Using a mixture of numeric and symbolic analysis on the ODEs of motion of the VG, for anisotropic light nonlinear damping, we demonstrate (up to an approximate average), that Bryan's law is affected by any form of such damping, causing pattern drift, compromising the accuracy of the VG.
Piping system damping data at higher frequencies
International Nuclear Information System (INIS)
Ware, A.G.
1987-01-01
Research has been performed at the Idaho National Engineering Laboratory (INEL) for the United States Nuclear Regulatory Commission (USNRC) to determine best-estimate damping values for dynamic analyses of nuclear piping systems excited in the 20 to 100 Hz frequency range. Vibrations in this frequency range are typical of fluid-induced transients, for which no formal pipe damping guidelines exist. The available data found in the open literature and the USNRC/INEL nuclear piping damping data bank were reviewed, and a series of tests on a straight 3-in. (76-mm) piping system and a 5-in. (127-mm) system with several bends and elbows were conducted as part of this research program. These two systems were supported with typical nuclear piping supports that could be changed from test to test during the series. The resulting damping values were ≥ those of the Pressure Vessel Research Committee (PVRC) proposal for unisulated piping. Extending the PVRC damping curve from 20 to 100 Hz at 3% of critical damping would give a satisfactory representation of the test data. This position has been endorsed by the PVRC Technical Committee on Piping Systems. 14 refs
Damping and non-linearity of a levitating magnet in rotation above a superconductor
International Nuclear Information System (INIS)
Druge, J; Jean, C; Laurent, O; Méasson, M-A; Favero, I
2014-01-01
We study the dissipation of moving magnets in levitation above a superconductor. The rotation motion is analyzed using optical tracking techniques. It displays a remarkable regularity together with long damping time up to several hours. The magnetic contribution to the damping is investigated in detail by comparing 14 distinct magnetic configurations and points towards amplitude-dependent dissipation mechanisms. The non-linear dynamics of the mechanical rotation motion is also revealed and described with an effective Duffing model. The magnetic mechanical damping is consistent with measured hysteretic cycles M(H) that are discussed within a modified critical state model. The obtained picture of the coupling of levitating magnets to their environment sheds light on their potential as ultra-low dissipation mechanical oscillators for high precision physics. (paper)
Gamma irradiation induced effects of butyl rubber based damping material
Chen, Hong-Bing; Wang, Pu-Cheng; Liu, Bo; Zhang, Feng-Shun; Ao, Yin-Yong
2018-04-01
The effects of gamma irradiation on the butyl rubber based damping material (BRP) at various doses in nitrogen were investigated in this study. The results show that irradiation leads to radiolysis of BRP, with extractives increasing from 14.9 ± 0.8% of control to 37.2 ± 1.2% of sample irradiated at 350 kGy, while the swelling ratio increasing from 294 ± 3% to 766 ± 4%. The further investigation of the extractives with FTIR shows that the newly generated extractives are organic compounds containing C-H and C˭C bonds, with molecular weight ranging from 26,500 to 46,300. SEM characterization shows smoother surface with holes disappearing with increasing absorbed doses, consistent with "softer" material because of radiolysis. Dynamic mechanical study of BRP show that tan δ first slightly then obviously increases with increasing absorbed dose, while storage modulus slightly decreases. The tensile testing shows that the tensile strength decreases while the elongation at break increases with increasing dose. The positron annihilation lifetime spectroscopy show no obvious relations between free volume parameters and the damping properties, indicating the complicated influencing factors of damping properties.
Damping of Quasi-stationary Waves Between Two Miscible Liquids
Duval, Walter M. B.
2002-01-01
Two viscous miscible liquids with an initially sharp interface oriented vertically inside a cavity become unstable against oscillatory external forcing due to Kelvin-Helmholtz instability. The instability causes growth of quasi-stationary (q-s) waves at the interface between the two liquids. We examine computationally the dynamics of a four-mode q-s wave, for a fixed energy input, when one of the components of the external forcing is suddenly ceased. The external forcing consists of a steady and oscillatory component as realizable in a microgravity environment. Results show that when there is a jump discontinuity in the oscillatory excitation that produced the four-mode q-s wave, the interface does not return to its equilibrium position, the structure of the q-s wave remains imbedded between the two fluids over a long time scale. The damping characteristics of the q-s wave from the time history of the velocity field show overdamped and critically damped response; there is no underdamped oscillation as the flow field approaches steady state. Viscous effects serve as a dissipative mechanism to effectively damp the system. The stability of the four-mode q-s wave is dependent on both a geometric length scale as well as the level of background steady acceleration.
Unimodal optimal passive electromechanical damping of elastic structures
International Nuclear Information System (INIS)
Ben Mekki, O; Bourquin, F; Merliot, E; Maceri, F
2013-01-01
In this paper, a new electromechanical damper is presented and used, made of a pendulum oscillating around an alternator axis and connected by a gear to the vibrating structure. In this way, the mechanical energy of the oscillating mass can be transformed into electrical energy to be dissipated when the alternator is branched on a resistor. This damping device is intrinsically non-linear, and the problem of the optimal parameters and of the best placement of this damper on the structure is studied. The optimality criterion chosen here is the maximum exponential time decay rate (ETDR) of the structural response. This criterion leads to new design formulas. The case of a bridge under construction is considered and the analytical results are compared with experimental ones, obtained on a mock-up made of a vertical tower connected to a free-end horizontal beam, to simulate the behavior of a cable-stayed bridge during the erection phase. Up to three electromechanical dampers are placed in order to study the multi-modal damping. The satisfactory agreement between the theoretical model and the experiments suggests that a multi-modal passive damping of electromagnetic type could be effective on lightweight flexible structures, when dampers are suitably placed. (paper)
Analisis Kinerja Local Area Network Menggunakan Router.
Hutahaean, Yosua
2012-01-01
Perangkat internetworking menawarkan komunikasi di antara segmen Local Area Network (LAN). Ada empat tipe utama perangkat internetworking ini: repeater, bridge, router, dan gateway. Perangkat ini dibedakan atas dasar system lapisan Open System Interconnection (OSI) yang digunakan, berfungsi sebagai media komunikasi dari LAN ke LAN. Pada Tugas Akhir ini penulis tertarik untuk membahas analisis kinerja Local Area Network (LAN) menggunakan Router yang menggunakan sistem antrian M/M/1 dimana j...
Backscattering and Nonparaxiality Arrest Collapse of Damped Nonlinear Waves
Fibich, G.; Ilan, B.; Tsynkov, S.
2002-01-01
The critical nonlinear Schrodinger equation (NLS) models the propagation of intense laser light in Kerr media. This equation is derived from the more comprehensive nonlinear Helmholtz equation (NLH) by employing the paraxial approximation and neglecting the backscattered waves. It is known that if the input power of the laser beam (i.e., L(sub 2) norm of the initial solution) is sufficiently high, then the NLS model predicts that the beam will self-focus to a point (i.e.. collapse) at a finite propagation distance. Mathematically, this behavior corresponds to the formation of a singularity in the solution of the NLS. A key question which has been open for many years is whether the solution to the NLH, i.e., the 'parent' equation, may nonetheless exist and remain regular everywhere, in particular for those initial conditions (input powers) that lead to blowup in the NLS. In the current study, we address this question by introducing linear damping into both models and subsequently comparing the numerical solutions of the damped NLH (boundary-value problem) with the corresponding solutions of the damped NLS (initial-value problem). Linear damping is introduced in much the same way as done when analyzing the classical constant-coefficient Helmholtz equation using the limiting absorption principle. Numerically, we have found that it provides a very efficient tool for controlling the solutions of both the NLH and NHS. In particular, we have been able to identify initial conditions for which the NLS solution does become singular. whereas the NLH solution still remains regular everywhere. We believe that our finding of a larger domain of existence for the NLH than that for the NLS is accounted for by precisely those mechanisms, that have been neglected when deriving the NLS from the NLH, i.e., nonparaxiality and backscattering.
International Nuclear Information System (INIS)
Challa, Vinod R; Prasad, M G; Fisher, Frank T
2009-01-01
Vibration energy harvesting is being pursued as a means to power wireless sensors and ultra-low power autonomous devices. From a design standpoint, matching the electrical damping induced by the energy harvesting mechanism to the mechanical damping in the system is necessary for maximum efficiency. In this work two independent energy harvesting techniques are coupled to provide higher electrical damping within the system. Here the coupled energy harvesting device consists of a primary piezoelectric energy harvesting device to which an electromagnetic component is added to better match the total electrical damping to the mechanical damping in the system. The first coupled device has a resonance frequency of 21.6 Hz and generates a peak power output of ∼332 µW, compared to 257 and 244 µW obtained from the optimized, stand-alone piezoelectric and electromagnetic energy harvesting devices, respectively, resulting in a 30% increase in power output. A theoretical model has been developed which closely agrees with the experimental results. A second coupled device, which utilizes the d 33 piezoelectric mode, shows a 65% increase in power output in comparison to the corresponding stand-alone, single harvesting mode devices. This work illustrates the design considerations and limitations that one must consider to enhance device performance through the coupling of multiple harvesting mechanisms within a single energy harvesting device
Damping parameter study of a perforated plate with bias flow
Mazdeh, Alireza
One of the main impediments to successful operation of combustion systems in industrial and aerospace applications including gas turbines, ramjets, rocket motors, afterburners (augmenters) and even large heaters/boilers is the dynamic instability also known as thermo-acoustic instability. Concerns with this ongoing problem have grown with the introduction of Lean Premixed Combustion (LPC) systems developed to address the environmental concerns associated with the conventional combustion systems. The most common way to mitigate thermo-acoustic instability is adding acoustic damping to the combustor using acoustic liners. Recently damping properties of bias flow initially introduced to liners only for cooling purposes have been recognized and proven to be an asset in enhancing the damping effectiveness of liners. Acoustic liners are currently being designed using empirical design rules followed by build-test-improve steps; basically by trial and error. There is growing concerns on the lack of reliability associated with the experimental evaluation of the acoustic liners with small size apertures. The development of physics-based tools in assisting the design of such liners has become of great interest to practitioners recently. This dissertation focuses primarily on how Large-Eddy Simulations (LES) or similar techniques such as Scaled Adaptive Simulation (SAS) can be used to characterize damping properties of bias flow. The dissertation also reviews assumptions made in the existing analytical, semi-empirical, and numerical models, provides a criteria to rank order the existing models, and identifies the best existing theoretical model. Flow field calculations by LES provide good insight into the mechanisms that led to acoustic damping. Comparison of simulation results with empirical and analytical studies shows that LES simulation is a viable alternative to the empirical and analytical methods and can accurately predict the damping behavior of liners. Currently the
Damping by heat conduction in the Timoshenko system: Fourier and Cattaneo are the same
Said-Houari, Belkacem
2013-08-01
We consider the Cauchy problem for the one-dimensional Timoshenko system coupled with heat conduction, wherein the latter is described by either the Cattaneo law or the Fourier law. We prove that heat dissipation alone is sufficient to stabilize the system in both cases, so that additional mechanical damping is unnecessary. However, the decay of solutions without the mechanical damping is found to be slower than that with mechanical damping. Furthermore, in contrast to earlier results of Said-Houari and Kasimov (2012) [10] and Fernández Sare and Racke (2009) [12], we find that the Timoshenko-Fourier and the Timoshenko-Cattaneo systems have the same decay rate. The rate depends on a certain number α (first identified by Santos et al., 2012 [11] in a related study in a bounded domain), which is a function of the parameters of the system. © 2013 Elsevier Inc.
Human-in-the-loop evaluation of RMS Active Damping Augmentation
Demeo, Martha E.; Gilbert, Michael G.; Scott, Michael A.; Lepanto, Janet A.; Bains, Elizabeth M.; Jensen, Mary C.
1993-01-01
Active Damping Augmentation is the insertion of Controls-Structures Integration Technology to benefit the on-orbit performance of the Space Shuttle Remote Manipulator System. The goal is to reduce the vibration decay time of the Remote Manipulator System following normal payload maneuvers and operations. Simulation of Active Damping Augmentation was conducted in the realtime human-in-the-loop Systems Engineering Simulator at the NASA Johnson Space Center. The objective of this study was to obtain a qualitative measure of operational performance improvement from astronaut operators and to obtain supporting quantitative performance data. Sensing of vibratory motions was simulated using a three-axis accelerometer mounted at the end of the lower boom of the Remote Manipulator System. The sensed motions were used in a feedback control law to generate commands to the joint servo mechanisms which reduced the unwanted oscillations. Active damping of the Remote Manipulator System with an attached 3990 lb. payload was successfully demonstrated. Six astronaut operators examined the performance of an Active Damping Augmentation control law following single-joint and coordinated six-joint translational and rotational maneuvers. Active Damping Augmentation disturbance rejection of Orbiter thruster firings was also evaluated. Significant reductions in the dynamic response of the 3990 lb. payload were observed. Astronaut operators recommended investigation of Active Damping Augmentation benefits to heavier payloads where oscillations are a bigger problem (e.g. Space Station Freedom assembly operators).
DEFF Research Database (Denmark)
Hagerhed, L.; Bornehag, Carl-Gustaf; Sundell, Jan
2002-01-01
Questionnaire data on 8681 dwellings included in the Swedish study "Dampness in Buildings and Health" have been analysed for associations between dampness indicators, perceptions of indoor air quality and building characteristics such as time of construction, type of ventilation and type of found......Questionnaire data on 8681 dwellings included in the Swedish study "Dampness in Buildings and Health" have been analysed for associations between dampness indicators, perceptions of indoor air quality and building characteristics such as time of construction, type of ventilation and type...... of "Dry air" in 17.3 and 33.7% respectively. Older buildings and the use of natural ventilation were associated with increased frequency of dampness indicators as well as to increased frequencies of complaints on bad indoor air quality....
Numerical studies of shear damped composite beams using a constrained damping layer
DEFF Research Database (Denmark)
Kristensen, R.F.; Nielsen, Kim Lau; Mikkelsen, Lars Pilgaard
2008-01-01
Composite beams containing one or more damping layers are studied numerically. The work is based on a semi-analytical model using a Timoshenko beam theory and a full 2D finite element model. The material system analysed, is inspired by a train wagon suspension system used in a EUREKA project Sigma......!1841. For the material system, the study shows that the effect of the damping layer is strongly influenced by the presence of a stiff constraining layer, that enforces large shear strain amplitudes. The thickness of the damping rubber layer itself has only a minor influence on the overall damping....... In addition, a large influence of ill positioned cuts in the damping layer is observed....
Unwrapped phase inversion with an exponential damping
Choi, Yun Seok
2015-07-28
Full-waveform inversion (FWI) suffers from the phase wrapping (cycle skipping) problem when the frequency of data is not low enough. Unless we obtain a good initial velocity model, the phase wrapping problem in FWI causes a result corresponding to a local minimum, usually far away from the true solution, especially at depth. Thus, we have developed an inversion algorithm based on a space-domain unwrapped phase, and we also used exponential damping to mitigate the nonlinearity associated with the reflections. We construct the 2D phase residual map, which usually contains the wrapping discontinuities, especially if the model is complex and the frequency is high. We then unwrap the phase map and remove these cycle-based jumps. However, if the phase map has several residues, the unwrapping process becomes very complicated. We apply a strong exponential damping to the wavefield to eliminate much of the residues in the phase map, thus making the unwrapping process simple. We finally invert the unwrapped phases using the back-propagation algorithm to calculate the gradient. We progressively reduce the damping factor to obtain a high-resolution image. Numerical examples determined that the unwrapped phase inversion with a strong exponential damping generated convergent long-wavelength updates without low-frequency information. This model can be used as a good starting model for a subsequent inversion with a reduced damping, eventually leading to conventional waveform inversion.
Damping and fluidelastic instability in two-phase cross-flow heat exchanger tube arrays
Moran, Joaquin E.
flux, and its dependency is a function of void fraction. A dimensional analysis was carried out to investigate the relationship between damping and two-phase flow related parameters. As a result, the inclusion of surface tension in the form of the Capillary number appears to be useful when combined with the two-phase component of the damping ratio (interfacial damping). A strong dependence of damping on flow regime was observed when plotting the interfacial damping versus the void fraction, introducing an improvement over the previous result obtained by normalizing the two-phase damping, which does not exhibit this behaviour. The interfacial velocity model was selected to represent the fluidelastic data in two-phase experiments, due to the inclusion of the tube array geometry and density ratio effects, which does not exist for the pitch velocity approach. An essential component in reliably establishing the velocity threshold for fluidelastic instability, is a measure of the energy dissipation available in the system to balance the energy input from the flow. The present analysis argues that the damping in-flow is not an appropriate measure and demonstrates that the use of quiescent fluid damping provides a better measure of the energy dissipation, which produces a much more logical trend in the stability behaviour. This value of damping, combined with the RAD density and the interfacial velocity, collapses the available data well and provides the expected trend of two-phase flow stability data over the void fraction range from liquid to gas flows. The resulting stability maps represent a significant improvement over existing maps for predicting fluidelastic instability of tube bundles in two-phase flows. This result also tends to confirm the hypothesis that the basic mechanism of fluidelastic instability is the same for single and two-phase flows.
Gravitational radiation resistance, radiation damping and field fluctuations
International Nuclear Information System (INIS)
Schaefer, G.
1981-01-01
Application is made of two different generalised fluctuation-dissipation theorems and their derivations to the calculation of the gravitational quadrupole radiation resistance using the radiation-reaction force given by Misner, Thorne and Wheeler (Gravitation (San Francisco: Freeman) ch 36,37 (1973)) and the usual tidal force on one hand and the tidal force and the free gravitational radiation field on the other hand. The quantum-mechanical version (including thermal generalisations) of the well known classical quadrupole radiation damping formula is obtained as a function of the radiation resistance. (author)
Use of electro-magnetic damping for vibration control
DEFF Research Database (Denmark)
Stein, George Juraj; Darula, Radoslav; Sorokin, Sergey
2012-01-01
to introduce additional electromagnetic damping into vibrating mechanical system. The hysteretic losses and eddy currents are included in the model, to take into account more realistic dynamic behaviour of the system. The mathematical model of the controller is derived using lumped parameter approach......Vibration of machines is an unwanted phenomenon, and it is usually of interest to eliminate it. There are various means to be used in order to reach the goal, where the utilization of the electromagnet augmented by an external shunt circuit is analyzed in the paper. The magnetic force is used...
Nuclear power plant piping damping parametric effects
International Nuclear Information System (INIS)
Ware, A.G.
1983-01-01
The NRC and EG and G Idaho are engaged in programs to evaluate piping-system damping, in order to provide realistic and less conservative values to be used in seismic analyses. To generate revised guidelines, solidly based on technical data, new experimental data need to be generated and assessed, and the parameters which influence piping-system damping need to be quantitatively identified. This paper presents the current state-of-the-art knowledge in the United States on parameters which influence piping-system damping. Examples of inconsistencies in the data and areas of uncertainty are explained. A discussion of programs by EG and G Idaho and other organizations to evaluate various effects are included, and both short-and long-range goals of the program are outlined
Radiation damping in focusing-dominated systems
International Nuclear Information System (INIS)
Huang, Zhirong; Chen, Pisin; Ruth, R.D.
1995-01-01
A quasi-classical method is developed to calculate the radiation damping of a relativistic particle in a straight, continuous focusing system. In one limiting case where the pitch angle of the particle θ p is much larger than the radiation opening angle 1/γ, the radiation power spectrum is similar to synchrotron radiation and the relative damping rate of the transverse action is proportional to the relative energy loss rate. In the other limiting case where θ p much-lt 1/γ, the radiation is dipole in nature and the relative damping rate of the transverse action is energy-independent and is much faster than the relative energy rate. Quantum excitation to the transverse action is absent in this focusing channel. These results can be extended to bent systems provided that the focusing field dominates over the bending field
Damping of wind turbine tower vibrations
DEFF Research Database (Denmark)
Brodersen, Mark Laier; Pedersen, Mikkel Melters
Damping of wind turbine vibrations by supplemental dampers is a key ingredient for the continuous use of monopiles as support for offshore wind turbines. The present thesis consists of an extended summary with four parts and appended papers [P1-P4] concerning novel strategies for damping of tower...... dominated vibrations.The first part of the thesis presents the theoretical framework for implementation of supplemental dampers in wind turbines. It is demonstrated that the feasibility of installing dampers at the bottom of the tower is significantly increased when placing passive or semiactive dampers...... in a stroke amplifying brace, which amplifies the displacement across the damper and thus reduces the desired level of damper force. For optimal damping of the two lowest tower modes, a novel toggle-brace concept for amplifying the bending deformation of the tower is presented. Numerical examples illustrate...
Minimum wakefield achievable by waveguide damped cavity
International Nuclear Information System (INIS)
Lin, X.E.; Kroll, N.M.
1995-01-01
The authors use an equivalent circuit to model a waveguide damped cavity. Both exponentially damped and persistent (decay t -3/2 ) components of the wakefield are derived from this model. The result shows that for a cavity with resonant frequency a fixed interval above waveguide cutoff, the persistent wakefield amplitude is inversely proportional to the external Q value of the damped mode. The competition of the two terms results in an optimal Q value, which gives a minimum wakefield as a function of the distance behind the source particle. The minimum wakefield increases when the resonant frequency approaches the waveguide cutoff. The results agree very well with computer simulation on a real cavity-waveguide system
Quantization of the damped harmonic oscillator revisited
Energy Technology Data Exchange (ETDEWEB)
Baldiotti, M.C., E-mail: baldiott@fma.if.usp.b [Instituto de Fisica, Universidade de Sao Paulo, Caixa Postal 66318-CEP, 05315-970 Sao Paulo, S.P. (Brazil); Fresneda, R., E-mail: fresneda@gmail.co [Instituto de Fisica, Universidade de Sao Paulo, Caixa Postal 66318-CEP, 05315-970 Sao Paulo, S.P. (Brazil); Gitman, D.M., E-mail: gitman@dfn.if.usp.b [Instituto de Fisica, Universidade de Sao Paulo, Caixa Postal 66318-CEP, 05315-970 Sao Paulo, S.P. (Brazil)
2011-04-11
We return to the description of the damped harmonic oscillator with an assessment of previous works, in particular the Bateman-Caldirola-Kanai model and a new model proposed by one of the authors. We argue the latter has better high energy behavior and is connected to existing open-systems approaches. - Highlights: We prove the local equivalence of two damped harmonic oscillator models. We find different high energy behaviors between the two models. Based on the local equivalence, we make a simple construction of the coherent states.
Quantization of the damped harmonic oscillator revisited
International Nuclear Information System (INIS)
Baldiotti, M.C.; Fresneda, R.; Gitman, D.M.
2011-01-01
We return to the description of the damped harmonic oscillator with an assessment of previous works, in particular the Bateman-Caldirola-Kanai model and a new model proposed by one of the authors. We argue the latter has better high energy behavior and is connected to existing open-systems approaches. - Highlights: → We prove the local equivalence of two damped harmonic oscillator models. → We find different high energy behaviors between the two models. → Based on the local equivalence, we make a simple construction of the coherent states.
Variable stiffness and damping MR isolator
Energy Technology Data Exchange (ETDEWEB)
Zhang, X Z; Wang, X Y; Li, W H; Kostidis, K [University of Wollongong, School of Mechanical, Materials and Mechatronic Engineering, NSW 2522 (Australia)], E-mail: weihuali@uow.edu.au
2009-02-01
This paper presents the development of a magnetorheological (MR) fluid-based variable stiffness and damping isolator for vibration suppressions. The MR fluid isolator used a sole MR control unit to achieve the variable stiffness and damping in stepless and relative large scope. A mathematical model of the isolator was derived, and a prototype of the MR fluid isolator was fabricated and its dynamic behavior was measured in vibration under various applied magnetic fields. The parameters of the model under various magnetic fields were identified and the dynamic performances of isolator were evaluated.
Damping in accelerators due to classical radiation
International Nuclear Information System (INIS)
Mills, F.E.
1962-01-01
The rates of change of the magnitudes of the adiabatic invariants is calculated in the case of a Hamiltonian system subjected to generalized non conservative forces. These results are applied to the case of the classical radiation of electrons in an accelerator or storage ring. The resulting expressions for the damping rates of three independent oscillation modes suggest structures which are damping in all three modes, while at the same time allowing 'strong focussing' and the attendant strong momentum compaction. (author)
Modulated Langmuir waves and nonlinear Landau damping
International Nuclear Information System (INIS)
Yajima, Nobuo; Oikawa, Masayuki; Satsuma, Junkichi; Namba, Chusei.
1975-01-01
The nonlinear Schroedinger euqation with an integral term, iusub(t)+P/2.usub(xx)+Q/u/ 2 u+RP∫sub(-infinity)sup(infinity)[/u(x',t)/ 2 /(x-x')]dx'u=0, which describes modulated Langmuir waves with the nonlinear Landau damping effect, is solved by numerical calculations. Especially, the effects of nonlinear Landau damping on solitary wave solutions are studied. For both cases, PQ>0 and PQ<0, the results show that the solitary waves deform in an asymmetric way changing its velocity. (auth.)
DEFF Research Database (Denmark)
Li, Hui; Liu, Shengquan; Ji, Haiting
2014-01-01
on the power system stabilizer (PSS) control method. Transient simulation on different damping gain coefficients are conducted for justification. Following the OTEF mechanism analysis, an additional fuzzy damping control strategy with the active/reactive power loop is proposed by identifying the oscillation......This study investigates the inter-area low-frequency damping control strategies of a doubly fed induction generator (DFIG)-based wind farm through oscillation transient energy function (OTEF) analysis. Based on the OTEF descent expressions, the feasibility of damping the inter-area low...... oscillation of the wind turbine shaft. The proposed additional fuzzy control strategy with the active/reactive power loop has better damping performance than the presented PSS control, especially for damping the inter-area low-frequency oscillation....
Particle Damping with Granular Materials for Multi Degree of Freedom System
Directory of Open Access Journals (Sweden)
Masanobu Inoue
2011-01-01
Full Text Available A particle damper consists of a bed of granular materials moving in cavities within a multi degree-of-freedom (MDOF structure. This paper deals with the damping effects on forced vibrations of a MDOF structure provided with the vertical particle dampers. In the analysis, the particle bed is assumed to be a single mass, and the collisions between the granules and the cavities are completely inelastic, i.e., all energy dissipation mechanisms are wrapped into zero coefficient of restitution. To predict the particle damping effect, equations of motion are developed in terms of equivalent single degree-of-freedom (SDOF system and damper mass with use made of modal approach. In this report, the periodic vibration model comprising sustained contact on or separation of the damper mass from vibrating structure is developed. A digital model is also formulated to simulate the damped motion of the physical system, taking account of all vibration modes. Numerical and experimental studies are made of the damping performance of plural dampers located at selected positions throughout a 3MDOF system. The experimental results confirm numerical prediction that collision between granules and structures is completely inelastic as the contributing mechanism of damping in the vertical vibration. It is found that particle dampers with properly selected mass ratios and clearances effectively suppress the resonance peaks over a wide frequency range.
Extracellular ATP acts as a damage associated molecular pattern (DAMP signal in plants
Directory of Open Access Journals (Sweden)
Kiwamu eTanaka
2014-09-01
Full Text Available As sessile organisms, plants have evolved effective mechanisms to protect themselves from environmental stresses. Damaged (i.e., wounded plants recognize a variety of endogenous molecules as danger signals, referred to as damage-associated molecular patterns (DAMPs. ATP is among the molecules that are released by cell damage, and recent evidence suggests that ATP can serve as a DAMP. Although little studied in plants, extracellular ATP is well known for its signaling role in animals, including acting as a DAMP during the inflammatory response and wound healing. If ATP acts outside the cell, then it is reasonable to expect that it is recognized by a plasma membrane-localized receptor. Recently, DORN1, a lectin receptor kinase, was shown to recognize extracellular ATP in Arabidopsis. DORN1 is the founding member of a new purinoceptor subfamily, P2K (P2 receptor Kinase, which is plant-specific. P2K1 (DORN1 is required for ATP-induced cellular responses (e.g., cytosolic Ca2+ elevation, MAPK phosphorylation, and gene expression. Genetic analysis of loss-of-function mutants and overexpression lines showed that P2K1 participates in the plant wound response, consistent with the role of ATP as a DAMP. In this review, we summarize past research on the roles and mechanisms of extracellular ATP signaling in plants, and discuss the direction of the future research of extracellular ATP as a DAMP signal.
López-Ruiz, F. F.; Guerrero, J.; Aldaya, V.; Cossío, F.
2012-08-01
Using a quantum version of the Arnold transformation of classical mechanics, all quantum dynamical systems whose classical equations of motion are non-homogeneous linear second-order ordinary differential equations (LSODE), including systems with friction linear in velocity such as the damped harmonic oscillator, can be related to the quantum free-particle dynamical system. This implies that symmetries and simple computations in the free particle can be exported to the LSODE-system. The quantum Arnold transformation is given explicitly for the damped harmonic oscillator, and an algebraic connection between the Caldirola-Kanai model for the damped harmonic oscillator and the Bateman system will be sketched out.
International Nuclear Information System (INIS)
López-Ruiz, F F; Guerrero, J; Aldaya, V; Cossío, F
2012-01-01
Using a quantum version of the Arnold transformation of classical mechanics, all quantum dynamical systems whose classical equations of motion are non-homogeneous linear second-order ordinary differential equations (LSODE), including systems with friction linear in velocity such as the damped harmonic oscillator, can be related to the quantum free-particle dynamical system. This implies that symmetries and simple computations in the free particle can be exported to the LSODE-system. The quantum Arnold transformation is given explicitly for the damped harmonic oscillator, and an algebraic connection between the Caldirola-Kanai model for the damped harmonic oscillator and the Bateman system will be sketched out.
Kajian Eksperimental Parameter Modal Bangunan Dua Lantai dengan Metode Modal Analisis
Directory of Open Access Journals (Sweden)
Islahuddin Islahuddin
2016-12-01
Full Text Available Abstrak: Pengukuran getaran merupakan kegiatan yang umum dilakukan dalam perawatan prediktif. Perawatan prediktifbiasanya menggunakan pengukuran sinyal getaran untuk mendeteksi kerusakan yang terjadi pada mesin. Sinyalgetaran yang terukur tersebut, kemudian ditransformasikan dalam bentuk grafik fungsi respon frekuensi (FRF.Selanjutnya FRF diolah sedemikian rupasehingga diperoleh modus getar struktur. Dari modus getar yang diperoleh,maka dapat dianalisa kemungkinan kerusakan yang terjadi pada mesin dengan melihat besarnya amplitudo getarannya.Penelitian ini bertujuan untuk menganalisa karakteristik dinamik dari sistem getaran yang terjadi pada model strukturbangunan dua lantai. Pengujian dilakukan denganmemberikan gaya eksitasi menggunakan impact hammer.Akselerometer digunakan mengukur sinyal getaran yang terjadi pada struktur. Posisi penempatan akselerometerdilakukan bervariasi untuk delapan titik pengujian yang berbeda. Sedangkan posisi pemberian gaya eksitasi tetap untuksemua titik pengujian. Pada penelitian ini menggunakan metode modal analisis eksperimen untuk mengetahuikarakteristik dinamik dari model struktur bangunan dua lantai. Teknik modal analisis ini digunakan untuk mendapatkanparameter modal seperti frekuensi, rasio redaman, dan modus getar. Hasil yang diperoleh dari penelitian inimenunjukkan bahwafrekuensi pribadipertama pada amplitudo maksimum mempunyai nilai yang sama, yaitu 2,313 Hz.Sedangkan untuk frekuensi pribadi kedua pada amplitudo maksimumnya terdapat perbedaan, yaitu pada titik pengujian3 dan 7. Hal ini dapat disebabkan oleh pemberian gaya eksitasi yang tidak sama dengan titik-titik pengujian yang lain.Kata kunci: Karakteristik dinamik, analisis modal eksperimen, frekuensi pribadi, FRF Abstract: Measuring vibration is an activity which is generally carried out in a predictive maintenance. In maintaining, vibratesignal measurement is usually used for machine damage detection. The signal measurement is then being
Dry friction damping couple at high frequencies
Czech Academy of Sciences Publication Activity Database
Půst, Ladislav; Pešek, Luděk; Košina, Jan; Radolfová, Alena
2014-01-01
Roč. 8, č. 1 (2014), s. 91-100 ISSN 1802-680X Institutional support: RVO:61388998 Keywords : dry friction * damping * high frequencies Subject RIV: BI - Acoustics http://www.kme.zcu.cz/acm/acm/article/view/239/265
Piezoelectric RL shunt damping of flexible structures
DEFF Research Database (Denmark)
Høgsberg, Jan Becker; Krenk, Steen
2015-01-01
in the present analysis is based on equal damping of the two modes associated with the resonant vibration form of the structure. An important result of the presented calibration procedure is the explicit inclusion of a quasi-static contribution from the non-resonant vibration modes of the structure via a single...
Active damping based on decoupled collocated control
Holterman, J.; de Vries, Theodorus J.A.; Auer, Frank; Gardonio, P.; Rafaely, B.
2002-01-01
High-precision machines typically suffer from small but persistent vibrations. As it is difficult to damp these vibrations by passive means, research at the Drebbel Institute at the University of Twente is aimed at the development of an active structural element that can be used for vibration
BNS damping of beam breakup instability
International Nuclear Information System (INIS)
Stupakov, G.V.
1997-08-01
The author studies BNS damping of the beam breakup instability in a simple model assuming a constant beam energy, flat bunch distribution, and a smooth transverse focusing. The model allows an analytic solution for a constant and linear wake functions. Scaling dimensionless parameters are derived and the beam dynamics is illustrated for the range of parameters relevant to the Stanford Linear Collider
Kicker for the SLC electron damping ring
International Nuclear Information System (INIS)
Bartelson, L.; Crawford, C.; Dinkel, J.; Kerns, Q.; Howell, J.; Snowdon, S.; Walton, J.
1987-01-01
The SLC electron damping ring requires two kickers each providing a 5 mr kick at 1.2 GEV to pairs of electron bunches spaced 61.63 nsec apart. The exact shape of the kick is unimportant, but the specification applies to the field the bunches see
Damping of liquid sloshing by foams
Sauret, A.; Boulogne, F.; Cappello, J.; Dressaire, E.; Stone, H. A.
2015-02-01
When a container is set in motion, the free surface of the liquid starts to oscillate or slosh. Such effects can be observed when a glass of water is handled carelessly and the fluid sloshes or even spills over the rims of the container. However, beer does not slosh as readily as water, which suggests that foam could be used to damp sloshing. In this work, we study experimentally the effect on sloshing of a liquid foam placed on top of a liquid bath. We generate a monodisperse two-dimensional liquid foam in a rectangular container and track the motion of the foam. The influence of the foam on the sloshing dynamics is experimentally characterized: only a few layers of bubbles are sufficient to significantly damp the oscillations. We rationalize our experimental findings with a model that describes the foam contribution to the damping coefficient through viscous dissipation on the walls of the container. Then we extend our study to confined three-dimensional liquid foam and observe that the behavior of 2D and confined 3D systems are very similar. Thus, we conclude that only the bubbles close to the walls have a significant impact on the dissipation of energy. The possibility to damp liquid sloshing using foam is promising in numerous industrial applications such as the transport of liquefied gas in tankers or for propellants in rocket engines.
Nuclear power plant piping damping parametric effects
International Nuclear Information System (INIS)
Ware, A.G.
1983-01-01
The present NRC guidelines for structural damping to be used in the dynamic stress analyses of nuclear power plant piping systems are generally considered to be overly conservative. As a result, plant designers have in many instances used a considerable number of seismic supports to keep stresses calculated by large scale piping computer codes below the allowable limits. In response to this problem, the NRC and EG and G Idaho are engaged in programs to evaluate piping system damping, in order to provide more realistic and less conservative values to be used in seismic analyses. To generate revised guidelines, solidly based on technical data, new experimental data need to be generated and assessed, and the parameters which influence piping system damping need to be quantitatively identified. This paper presents the current state-of-the-art knowledge in the United States on parameters which influence piping system damping. Examples of inconsistencies in the data and areas of uncertainty are explained. A discussion of programs by EG and G Idaho and other organizations to evaluate various effects is included, and both short and long range goals of the program are outlined
Factors controlling superelastic damping capacity of SMAs
Czech Academy of Sciences Publication Activity Database
Heller, Luděk; Šittner, Petr; Pilch, Jan; Landa, Michal
2009-01-01
Roč. 18, 5-6 (2009), 603-611 ISSN 1059-9495 Institutional research plan: CEZ:AV0Z10100520; CEZ:AV0Z20760514 Keywords : shape memory alloys * superelastic damping * thermomechanical testing Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.592, year: 2009
Structural dynamic modification using additive damping
Indian Academy of Sciences (India)
elements, FEM and perturbation methods for reanalysis or structural dynamic modification ... to a system changes its mass, stiffness and damping. Thus ... due to the phase difference between stress ' and strain or 'a И E1 З iE2 for direct strain.
Spatial Damping of Linear Compressional Magnetoacoustic Waves ...
Indian Academy of Sciences (India)
The uncertainty in the radiative relaxation time, how- ever, does .... For spatial damping, we take ω to be real and k to be complex as kR +ikI . The disper- ... bances may travel up in the solar atmosphere through the magnetic field lines that are.
Contact stiffness and damping of liquid films in dynamic atomic force microscope
International Nuclear Information System (INIS)
Xu, Rong-Guang; Leng, Yongsheng
2016-01-01
The mechanical properties and dissipation behaviors of nanometers confined liquid films have been long-standing interests in surface force measurements. The correlation between the contact stiffness and damping of the nanoconfined film is still not well understood. We establish a novel computational framework through molecular dynamics (MD) simulation for the first time to study small-amplitude dynamic atomic force microscopy (dynamic AFM) in a simple nonpolar liquid. Through introducing a tip driven dynamics to mimic the mechanical oscillations of the dynamic AFM tip-cantilever assembly, we find that the contact stiffness and damping of the confined film exhibit distinct oscillations within 6-7 monolayer distances, and they are generally out-of-phase. For the solid-like film with integer monolayer thickness, further compression of the film before layering transition leads to higher stiffness and lower damping, while much lower stiffness and higher damping occur at non-integer monolayer distances. These two alternating mechanisms dominate the mechanical properties and dissipation behaviors of simple liquid films under cyclic elastic compression and inelastic squeeze-out. Our MD simulations provide a direct picture of correlations between the structural property, mechanical stiffness, and dissipation behavior of the nanoconfined film.
Contact stiffness and damping of liquid films in dynamic atomic force microscope
Energy Technology Data Exchange (ETDEWEB)
Xu, Rong-Guang; Leng, Yongsheng, E-mail: leng@gwu.edu [Department of Mechanical and Aerospace Engineering, The George Washington University, Washington, DC 20052 (United States)
2016-04-21
The mechanical properties and dissipation behaviors of nanometers confined liquid films have been long-standing interests in surface force measurements. The correlation between the contact stiffness and damping of the nanoconfined film is still not well understood. We establish a novel computational framework through molecular dynamics (MD) simulation for the first time to study small-amplitude dynamic atomic force microscopy (dynamic AFM) in a simple nonpolar liquid. Through introducing a tip driven dynamics to mimic the mechanical oscillations of the dynamic AFM tip-cantilever assembly, we find that the contact stiffness and damping of the confined film exhibit distinct oscillations within 6-7 monolayer distances, and they are generally out-of-phase. For the solid-like film with integer monolayer thickness, further compression of the film before layering transition leads to higher stiffness and lower damping, while much lower stiffness and higher damping occur at non-integer monolayer distances. These two alternating mechanisms dominate the mechanical properties and dissipation behaviors of simple liquid films under cyclic elastic compression and inelastic squeeze-out. Our MD simulations provide a direct picture of correlations between the structural property, mechanical stiffness, and dissipation behavior of the nanoconfined film.
A review of experimental soil-structure interaction damping
International Nuclear Information System (INIS)
Tsai, N.C.
1981-01-01
In soil-structure interaction analysis, the foundation soil is usually represented by impedance springs and dampers. The impedance damping includes the effect of both the material damping and the radiation damping. Because the impedance theory normally assumes a rigid structural base and an elastic bond between the soil and structure, it is generally held that the radiation damping has been overestimated by the theory. There are some published information on the dynamic tests of footings and structures that allow direct or indirect assessments of the validity of the analytical radiation damping. An overview of such information is presented here. Based on these limited test data, it is concluded that for horizontal soil-structure interaction analysis the analytical radiation damping alone is sufficient to represent the combined material and radiation damping in the field. On the other hand, for vertical analysis it appears that the theory may have overestimated the radiation damping and certain reduction is recommended. (orig.)
Damped time advance methods for particles and EM fields
International Nuclear Information System (INIS)
Friedman, A.; Ambrosiano, J.J.; Boyd, J.K.; Brandon, S.T.; Nielsen, D.E. Jr.; Rambo, P.W.
1990-01-01
Recent developments in the application of damped time advance methods to plasma simulations include the synthesis of implicit and explicit ''adjustably damped'' second order accurate methods for particle motion and electromagnetic field propagation. This paper discusses this method
Exponential decay for solutions to semilinear damped wave equation
Gerbi, Sté phane; Said-Houari, Belkacem
2011-01-01
This paper is concerned with decay estimate of solutions to the semilinear wave equation with strong damping in a bounded domain. Intro- ducing an appropriate Lyapunov function, we prove that when the damping is linear, we can find initial data
Salt Damage and Rising Damp Treatment in Building Structures
Directory of Open Access Journals (Sweden)
J. M. P. Q. Delgado
2016-01-01
Full Text Available Salt damage can affect the service life of numerous building structures, both historical and contemporary, in a significant way. In this review, various damage mechanisms to porous building materials induced by salt action are analyzed. The importance of pretreatment investigations is discussed as well; in combination with the knowledge of salt and moisture transport mechanisms they can give useful indications regarding treatment options. The methods of salt damage treatment are assessed then, including both passive techniques based on environmental control, reduction of water transport, or conversion to less soluble salts and active procedures resulting in the removal of salts from deterioration zones. It is concluded that cellulose can still be considered as the favorite material presently used in desalination poultices but hydrophilic mineral wool can serve as its prospective alternative in future applications. Another important cause of building pathologies is the rising damp and, in this phenomenon, it is particularly severe considering the presence of salts in water. The treatment of rising damp in historic building walls is a very complex procedure and at Laboratory of Building Physics (LFC-FEUP a wall base hygroregulated ventilation system was developed and patented.
Damping at high homologous temperature in pure Cd, In, Pb, and Sn
International Nuclear Information System (INIS)
Cook, L.S.; Lakes, R.S.
1995-01-01
Typically, if a material possesses the stiffness necessary to be considered a structural material, its damping is low. Conversely, materials with high damping usually do not possess the stiffness necessary to be considered a structural material. Candidate materials for the high stiffness-low damping phase exist in abundance, whereas candidate materials for the moderate stiffness-high damping phase remain to be identified. One possible class of candidate materials for the moderate stiffness-high damping phase is metals at high homologous temperatures. Shear moduli of the specimens at 100 Hz are as follows: 4.1 GPa for indium, 5.7 GPa for lead, 15.7 GPa for tin, and 20.7 GPa for cadmium. Considering the behavior typical of metals, one may think of In and Pb as relatively compliant, while Sn and Cd could be called moderately stiff. The results are of some technological interest in view of the utility of materials with moderately high stiffness and damping. The combination of moderate stiffness and reasonably high loss tangent makes Cd the most promising metal tested with respect to technological applications. The shear modulus of Cd was highest of the metals tested (and very near that of aluminum (G = 27 GPa), which exhibits a loss tangent of about 0.001 at room temperature). The loss tangent of Cd at audio-frequencies was as high or higher than that of the other metals. In addition, frequency dependence of loss tangent was not as large as that observed in the other metals. No clear pattern relating damping to melting point emerged. An understanding in terms of viscoelastic mechanisms is not forthcoming at this time. Among the metal studied, cadmium exhibited a substantial loss tangent of 0.03 to 0.04 over much of the audio range, combined with a moderate stiffness, G = 20.7 GPa
Ismail, Nik Intan Nik; Kamaruddin, Shamsul
2017-12-01
Magnetorheological elastomers (MREs) are composite materials consist of micron-sized magnetizable particles carbonyl iron particles [CIPs]) embedded in a soft elastomer matrix. MRE technology offers variable stiffness and damping properties under the influence of a magnetic field. Herein, the feasibility of incorporating a new generation specialty rubber, Pureprena as a matrix for MREs was investigated. Pureprena or Deproteinised Natural Rubber (DPNR) is a specialty natural rubber that has good dynamic properties, particularly with respect to damping parameters. DPNR was compounded with 60 wt% of CIPs to fabricate MREs. The performance of the DPNR-based MRE was measured in terms of tensile strength, dynamic properties, and magnetorheological (MR) effect and compared with polyisoprene (IR)-based MRE with the same amount of CIPs. Dynamic Mechanical Analyzer (DMA) showed that the loss factor in the glass transition region of the DPNR-based MRE was higher than that of the IR-based MRE, indicating better damping properties. Further investigation was undertaken using a servo-hydraulic testing machine to characterise the effect of strain amplitude and frequency on the dynamic properties (e.g. damping coefficient) of MREs at zero magnetic fields. The results demonstrate that DPNR-based MREs possess a comparable damping coefficient to that of IR-based MREs. In addition, MR effect, which relates to the ratio between elastic modulus with applied magnetic field (on-state) to the same modulus without applied fields (off-state), was measured using a parallel plate rheometer. As a result, DPNR-based MREs have improved MR effect than that of IR-based MREs. Moreover, variable stiffness is obtained when the magnetic field was increased to 0.8T. Loss factor or tan δ of MREs was found to vary against different magnetic fields. Finally, MREs with varied stiffness and damping were found to have potential as active control devices for smart damping materials.
Onset of chaos in Josephson junctions with intermediate damping
International Nuclear Information System (INIS)
Yao, X.; Wu, J.Z.; Ting, C.S.
1990-01-01
By use of the analytical solution of the Stewart-McCumber equation including quadratic damping and dc bias, the Melnikov method has been extended to the parameter regions of intermediate damping and dc bias for the Josephson junctions with quadratic damping and with linear damping and cosφ term. The comparison between the thresholds predicted by the Melnikov method and that derived from numerical simulation has been studied. In addition, the validity conditions for the Melnikov threshold are also discussed
ANALISIS PERIKANAN HUHATE DI PERAIRAN LARANTUKA, FLORES
Directory of Open Access Journals (Sweden)
Mohamad Adha Akbar
2016-11-01
Full Text Available Informasi mengenai beberapa aspek perikanan huhate sangat diperlukan sebagai bahan untuk perencanaan pengelolaan perikanan yang berkelanjutan. Penelitian ini dilakukan di Larantuka, Flores Timur pada tahun 2014 dengan tujuan untuk menganalisis perikanan huhate sebagai salah satu tulang punggung perikanan TCT. Kegiatan penelitian diprioritaskan pada analisis unit alat tangkap, daerah penangkapan, komposisi hasil tangkapan dan estimasi Total Faktor Produktivitas (TFP perikanan huhate. Basis data pengukuran adalah himpunan data pendaratan dan observasi lapang. Hasil penelitian menunjukan bahwa karakteristik armada terdiri dari kapal yang terbuat dari fibreglass dengan kisaran bobot kapal 6 - 30 GT. Daerah penangkapan di sekitar perairan Laut Sawu dan Laut Flores. Hasil tangkapan utama didominansi oleh cakalang (Katsuwonus pelamis sebanyak 82%, juwana tuna (Thunnus spp. 17% dan tongkol (Auxis spp. 1% serta hasil tangkapan ikutan lemadang (Coryphaena hippurus dan marlin (Makaira spp. < 1%. Hasil analisis tangkapan per unit upaya (CPUE memberikan nilai rata-rata sebesar 1,1 ton/trip (0,4-1,7 ton/trip dengan nilai tertinggi terjadi pada Februari, sedangkan terendah terjadi pada Januari. Hasil penelitian menunjukkan terdapat hubungan yang signifikan antara tren bulanan CPUE dan nilai TFP.
ANALISIS PENGELOLAAN LINGKUNGAN PERMUKIMAN DI KABUPATEN SOPPENG
Directory of Open Access Journals (Sweden)
Bakhrani Rauf
2016-08-01
Full Text Available Penelitian ini bertujuan untuk mendeskripsikan pengelolaan lingkungan permukiman di Kabupaten Soppeng pada aspek: (1 penyediaan dan penanganan lahan terbuka hijau (open space; (2 penyediaan dan penanganan drainase; (3 penanganan sampah; (4 penyediaan dan penanganan pembuangan veses (septic tank. Jenis penelitian ini adalah penelitian kuantitatif dengan pendekatan survei. Sampel wailayah penelitian ini adalah satu RW di ibu kota kabupaten dan satu RW di desa yang dipilih dengan metode purpossive sampling, yaitu RW yang sudah maju di ibu kota kabupaten dan RW yang tertinggal di desa. Responden sebanyak 50 kepala keluarga yakni masing-masing 25 kepala keuarga di setiap RW, dipilih dengan systematic random sampling. Teknik pengumpulan data yang dilakukan adalah melakukan observasi langsung dan dilengkapi dengan wawancara terhadap responden. Analisis yang digunakan adalah analisis deskriptif. Hasil penelitian menunjukkan bahwa pengelolaan lingkungan permukiman di Kabupaten Soppeng pada aspek: (1 ketersediaan dan penanganan lahan terbuka hijau (open space ditemukan belum memadai; (2 ketersediaan drainase (air kotor dan air hujan ditemukan belum memadai; (3 Penanganan sampahbelum memadai; dan (4 penanganan veses dan penyediaan septic tankbelum memadai.
Rosenberg, John H; Rai, Vikrant; Dilisio, Matthew F; Sekundiak, Todd D; Agrawal, Devendra K
2017-12-01
Osteoarthritis (OA) is a degenerative disease characterized by the destruction of cartilage. The greatest risk factors for the development of OA include age and obesity. Recent studies suggest the role of inflammation in the pathogenesis of OA. The two most common locations for OA to occur are in the knee and hip joints. The knee joint experiences more mechanical stress, cartilage degeneration, and inflammation than the hip joint. This could contribute to the increased incidence of OA in the knee joint. Damage-associated molecular patterns (DAMPs), including high-mobility group box-1, receptor for advanced glycation end products, and alarmins (S100A8 and S100A9), are released in the joint in response to stress-mediated chondrocyte and cartilage damage. This facilitates increased cartilage degradation and inflammation in the joint. Studies have documented the role of DAMPs in the pathogenesis of OA; however, the comparison of DAMPs and its influence on OA has not been discussed. In this study, we compared the DAMPs between OA knee and hip joints and found a significant difference in the levels of DAMPs expressed in the knee joint compared to the hip joint. The increased levels of DAMPs suggest a difference in the underlying pathogenesis of OA in the knee and the hip and highlights DAMPs as potential therapeutic targets for OA in the future.
Stabilization of solutions to higher-order nonlinear Schrodinger equation with localized damping
Directory of Open Access Journals (Sweden)
Eleni Bisognin
2007-01-01
Full Text Available We study the stabilization of solutions to higher-order nonlinear Schrodinger equations in a bounded interval under the effect of a localized damping mechanism. We use multiplier techniques to obtain exponential decay in time of the solutions of the linear and nonlinear equations.
On damping of screw dislocation bending vibrations in dissipative crystal: limiting cases
Dezhin, V. V.
2018-03-01
The expression for the generalized susceptibility of the dislocation obtained earlier was used. The electronic drag mechanism of dislocations is considered. The study of small dislocation oscillations was limited. The contribution of the attenuation of low-frequency bending screw dislocation vibrations to the overall coefficient of dynamic dislocation drag in the long-wave and short-wave limits is calculated. The damping of short-wave bending screw dislocation vibrations caused by an external action of an arbitrary frequency has been investigated. The contribution of long-wave bending screw dislocation vibrations damping in the total drag coefficient at an arbitrary frequency is found.
Directory of Open Access Journals (Sweden)
Jianye Dai
2013-01-01
Full Text Available The phenomenon that the same syndrome turns up in different diseases appears in the sight of people around the world, which raises the thought for possibility of “Same Treatment for Different Diseases.” Actually, treatment based on ZHENG classification in Traditional Chinese Medicine could bring revelation for the former finding. The dampness-heat syndrome in chronic hepatitis B and nonalcoholic fatty liver is regarded as the breakthrough point. We discussed the molecular mechanism of similar connotation that exists in chronic hepatitis B and nonalcoholic fatty liver by metabonomics to give the modern understanding of dampness-heat syndrome. Both urine and serum metabolic profiling revealed that obvious differences existed between dampness-heat syndrome and non-dampness-heat syndrome but the commonality was proved to appear in chronic hepatitis B and nonalcoholic fatty liver patients with dampness-heat syndrome. Furthermore, disorder of body fluid metabolism, decline in digestive capacity, and imbalance of intestinal flora were found to be the new guiding for treatment, with the hope to provide the basis for Chinese personalized medicine.
IDENTIFIKASI MISKONSEPSI SISWA SMP PADA KONSEP FOTOSINTESIS MELALUI ANALISIS GAMBAR
Directory of Open Access Journals (Sweden)
Devi Ariandini
2014-01-01
Full Text Available Tujuan dari penelitian ini adalah untuk mengidentifikasi miskonsepsi siswa dengan analisis menggambar. Tiga puluh empat siswa di kelas 8 di sekolah menengah pertama digunakan sebagai subyek dalam penelitian ini. Teknik sampel menggunakan teknik purposive sampling. Data yang diperlukan untuk penelitian ini dikumpulkan melalui kuesioner, menggambar analisis rubrik, dan wawancara. Identifikasi Kesalahpahaman ditentukan dengan menggambar siswa berdasarkan menggambar kriteria klasifikasi oleh Kose (2008. Siswa diperintahkan untuk menarik tentang konsep fotosintesis setelah proses pembelajaran. Gambar siswa dianalisis dengan rubrik dan setelah itu mereka diwawancarai. Hasil penelitian menunjukkan tidak semua tingkat kriteria menggambar dari tingkat 1 sampai 5 diidentifikasi. Dari hasil analisa, gambar paling banyak ditemukan adalah pada tingkat 4. Gambar pada tingkat 4 dikategorikan sebagai gambar lengkap konsep fotosintesis dan tidak ada kesalahpahaman ditemukan. Berdasarkan gambar mereka, ada siswa 2,9% diidentifikasi yang diselenggarakan kesalahpahaman. Ada perbedaan jumlah siswa yang diadakan kesalahpahaman antara gambar hasil analisis dan hasil wawancara. Dari hasil wawancara, ada siswa 35,2% dimiliki kesalahpahaman, lebih dari menggambar hasil analisis. Ini berarti bahwa identifikasi kesalahpahaman melalui analisis gambar tidak efektif. Kesalahpahaman siswa yang paling sering terjadi pada konsep fotosintesis adalah tempat berlangsungnya fotosintesis. Faktor yang membuat kesalahpahaman siswa yaitu karena siswa itu sendiri dan lingkungannya. Kata Kunci: fotosintesis, kesalahpahaman, konsep, menggambar analisis
On the origin of nonlocal damping in plasmonic monomers and dimers
DEFF Research Database (Denmark)
Tserkezis, Christos; Yan, Wei; Hsieh, Wenting
2017-01-01
The origin and importance of nonlocal damping is discussed through simulations with the generalized nonlocal optical response (GNOR) theory, in conjunction with time-dependent density functional theory (TDDFT) calculations and equivalent circuit modeling, for some of the most typical plasmonic...... architectures: metalâ€“dielectric interfaces, metalâ€“dielectricâ€“metal gaps, spherical nanoparticles and nanoparticle dimers. It is shown that diffusive damping, as introduced by the convectiveâ€“diffusive GNOR theory, describes well the enhanced losses and plasmon broadening predicted by ab initio...... the interface. Diffusive nonlocal theories provide therefore an efficient means to tackle plasmon damping when electron tunneling can be safely disregarded, without the need to resort to more accurate, but time-consuming fully quantum-mechanical studies....
Damping behavior of polymer composites with high volume fraction of NiMnGa powders
Sun, Xiaogang; Song, Jie; Jiang, Hong; Zhang, Xiaoning; Xie, Chaoying
2011-03-01
Polymer composites inserted with high volume fraction (up to 70 Vol%) of NiMnGa powders were fabricated and their damping behavior was investigated by dynamic mechanical analysis. It is found that the polymer matrix has little influence on the transformation temperatures of NiMnGa powders. A damping peak appears for NiMnGa/epoxy resin (EP) composites accompanying with the martensitic transformation or reverse martensitic transformation of NiMnGa powders during cooling or heating. The damping capacity for NiMnGa/EP composites increases linearly with the increase of volume fraction of NiMnGa powders and, decreases dramatically as the test frequency increases. The fracture strain of NiMnGa/EP composites decrease with the increase of NiMnGa powders.
Modification and damping of Alfven waves in a magnetized dusty plasma
International Nuclear Information System (INIS)
Salimullah, M.; Dasgupta, B.; Watanabe, K.; Sato, T.
1994-10-01
The dispersion characteristics of the circularly polarized electromagnetic waves along a homogeneous magnetic field in a dusty plasma have been investigated theoretically. The Vlasov equation has been employed to find the response of the magnetized plasma particles where the dust grains form a static background of highly charged and massive centers having certain correlation. It is found that in addition to the usual Landau damping which is negligible in the low temperature approximation, a novel mechanism of damping of the Alfven waves due to the dust comes into play. The modification and damping of the Alfven waves depend on the dust perturbation parameters, unequal densities of plasma particles, the average correlation length of the dust grains, temperature of the plasma and the magnetic field. (author)
Temperature dependent elasticity and damping in dehydrated sandstone
Darling, T. W.; Struble, W.
2013-12-01
Work reported previously at this conference, outlining our observation of anomalously large elastic softening and damping in dehydrated Berea sandstone at elevated temperatures, has been analysed to study shear and compressional effects separately. Modeling of the sample using COMSOL software was necessary to identify modes, as the vibration spectrum of the sample is poorly approximated by a uniform isotropic solid. The first torsional mode of our evacuated, dry, core softens at nearly twice the rate of Young's modulus modes (bending and compressional) and is also damped nearly twice as strongly as temperature increases. We consider two possible models for explaining this behavior, based on the assumption that the mechanical properties of the sandstone are dominated by the framework of quartz grains and polycrystalline cementation, neglecting initially the effects of clay and feldspar inclusions. The 20cm x 2.54cm diameter core is dry such that the pressure of water vapor in the experiment chamber is below 1e-6 Torr at 70C, suggesting that surface water beyond a small number of monolayers is negligible. Our models consider (1) enhanced sliding of grain boundaries in the cementation at elevated temperature and reduced internal water content, and (2) strain microcracking of the cementatioin at low water content due to anisotropic expansion in the quartz grains. In model (1) interfaces parallel to polyhedral grain surfaces were placed in the cement bonds and assigned frictional properties. Model (2) has not yet been implemented. The overall elasticity of a 3-D several-grain model network was determined by modeling quasistatic loading and measuring displacements. Initial results with a small number of grains/bonds suggests that only the first model provides softening and damping for all the modes, however the details of the effects of defect motioin at individual interfaces as the source for the frictional properties is still being evaluated. Nonlinear effects are
International Nuclear Information System (INIS)
Mills, D.L.; Arias, Rodrigo
2006-01-01
The Landau-Lifschitz-Gilbert (LLG) equation is used widely in device design to describe spin motions in magnetic nanoscale structures. The damping term in this equation plays an essential role in the description of the magnetization dynamics. The form of this term is simple and appealing, but it is derived through use of elementary phenomenological considerations. An important question is whether or not it provides a proper description of the damping of the magnetization in real materials. Recently, it was predicted that a mechanism called two magnon damping should contribute importantly to linewidths and consequently spin damping in ultrathin ferromagnetic films. This process yields ferromagnetic resonance (FMR) linewidths whose frequency dependence is incompatible with the linear variation expected from the Landau-Lifschitz equation. This prediction has now been confirmed experimentally. Furthermore, subsequent experimental and theoretical studies have demonstrated that the damping rate depends strongly on wave vector as well. It is thus clear that for many samples, the LLG equation fails to account for the systematics of the damping of the magnetization in ultrathin ferromagnets, at the linear response level. The paper will review the recent literature on this topic relevant to this issue. One must then inquire into the nature of a proper phenomenology to describe these materials. At the linear response level, the theory of the two magnon mechanism is sufficiently complete that one can describe the response of these systems without resort to LLG phenomenology. However, currently there is very great interest in the large amplitude response of the magnetization in magnetic nanostructures. In the view of the authors, it is difficult to envision a generally applicable extension of linear response theory into the large amplitude regime
Analisis Tingkat Kepentingan Dan Kinerja Layanan Automated Teller Machine (Atm) Bank Mandiri
Setiawati, Lenny; Sugiharto, Toto
2008-01-01
Penelitian ini ditujukan untuk menganalisis tingkat kepentingan dan kinerja layananATM Bank Mandiri. Analisis Servqual yang terdiri atas dimensi tangible, realibility,responsiveness, assurance,dan empathy digunakan untuk menganalisis kinerjalayanan ATM. Sementara itu, Customer Satisfaction Index dan ImportancePerformance Analysis yang terdiri atas analisis kuadran dan analisis kesenjangandigunakan untuk menginvestigasi kepuasan pelanggan dan untuk mengidentifikasikandimensi layanan yang kiner...
Damping of Crank–Nicolson error oscillations
DEFF Research Database (Denmark)
Britz, Dieter; Østerby, Ole; Strutwolf, J.
2003-01-01
The Crank–Nicolson (CN) simulation method has an oscillatory response to sharp initial transients. The technique is convenient but the oscillations make it less popular. Several ways of damping the oscillations in two types of electrochemical computations are investigated. For a simple one......-dimensional system with an initial singularity, subdivision of the first time interval into a number of equal subintervals (the Pearson method) works rather well, and so does division with exponentially increasing subintervals, where however an optimum expansion parameter must be found. This method can...... be computationally more expensive with some systems. The simple device of starting with one backward implicit (BI, or Laasonen) step does damp the oscillations, but not always sufficiently. For electrochemical microdisk simulations which are two-dimensional in space and using CN, the use of a first BI step is much...
Damping system immersed in a fluid
International Nuclear Information System (INIS)
1980-01-01
The invention relates to a damping system which is immersed in a fluid and allows slow motion, while opposing fast motion of a mobile or deformable system immersed in a fluid. Nuclear reactors utilize fabricated assemblies immmersed in the spent fuel storage pool to support the fuel elements placed in the pool, e.g., when refueling the reactor. These fabricated assemblies must be held in position, relative to the concrete walls of the pool, so as to allow slow deformation of the assemblies due to thermal expansion, while curbing fast motion, e.g., earthquake-induced motion. Such fast motion due to earthquakes might be the cause of resonance phenomena involving the fuel storage rack structure and the pool walls, should the rack structure and pool walls have the same resonant frequency. In the event of an earthquake, the damping system would provide for fast curbing of structure motion to prevent uncontrolled deformation which might result in breaks and destruction [fr
Barotropic FRW cosmologies with Chiellini damping
Energy Technology Data Exchange (ETDEWEB)
Rosu, Haret C., E-mail: hcr@ipicyt.edu.mx [IPICyT, Instituto Potosino de Investigacion Cientifica y Tecnologica, Camino a la presa San José 2055, Col. Lomas 4a Sección, 78216 San Luis Potosí, SLP (Mexico); Mancas, Stefan C., E-mail: stefan.mancas@erau.edu [Department of Mathematics, Embry–Riddle Aeronautical University, Daytona Beach, FL 32114-3900 (United States); Chen, Pisin, E-mail: pisinchen@phys.ntu.edu.tw [Leung Center for Cosmology and Particle Astrophysics (LeCosPA) and Department of Physics, National Taiwan University, Taipei 10617, Taiwan (China)
2015-05-08
It is known that barotropic FRW equations written in the conformal time variable can be reduced to simple linear equations for an exponential function involving the conformal Hubble rate. Here, we show that an interesting class of barotropic universes can be obtained in the linear limit of a special type of nonlinear dissipative Ermakov–Pinney equations with the nonlinear dissipation built from Chiellini's integrability condition. These cosmologies, which evolutionary are similar to the standard ones, correspond to barotropic fluids with adiabatic indices rescaled by a particular factor and have amplitudes of the scale factors inverse proportional to the adiabatic index. - Highlights: • Chiellini-damped Ermakov–Pinney equations are used in barotropic FRW cosmological context. • Chiellini-damped scale factors of the barotropic FRW universes are introduced. • These scale factors are similar to the undamped ones.
WAKEFIELD DAMPING FOR THE CLIC CRAB CAVITY
Ambattu, P; Dexter, A; Carter, R; Khan, V; Jones, R; Dolgashev, V
2009-01-01
A crab cavity is required in the CLIC to allow effective head-on collision of bunches at the IP. A high operating frequency is preferred as the deflection voltage required for a given rotation angle and the RF phase tolerance for a crab cavity are inversely proportional to the operating frequency. The short bunch spacing of the CLIC scheme and the high sensitivity of the crab cavity to dipole kicks demand very high damping of the inter-bunch wakes, the major contributor to the luminosity loss of colliding bunches. This paper investigates the nature of the wakefields in the CLIC crab cavity and the possibility of using various damping schemes to suppress them effectively.
System Reduction and Damping of Flexible Structures
DEFF Research Database (Denmark)
Høgsberg, Jan Riess; Krenk, Steen
2007-01-01
An increasing number of flexible structures such as cable-stayed bridges, pedestrian bridges and high-rise buildings are fitted with local dampers to mitigate vibration problems. In principle the effect of local dampers can be analyzed by use of complex modes, e.g. in conjunction with an averaging...... technique for local linearization of the damper characteristics. However, the complex mode shapes and frequencies depend on the magnitude of the damper and therefore are less suitable for design of the damper system. An efficient alternative consists in the use of a two-component representation...... of the damped modes of the structure. The idea is to represent the damped mode as a linear combination of the modes that occur in two distinctly different situations representing extreme conditions: the mode shape of the structure without the damper(s), and the mode shape of the structure, when the damper...
Negative mobility of a Brownian particle: Strong damping regime
Słapik, A.; Łuczka, J.; Spiechowicz, J.
2018-02-01
We study impact of inertia on directed transport of a Brownian particle under non-equilibrium conditions: the particle moves in a one-dimensional periodic and symmetric potential, is driven by both an unbiased time-periodic force and a constant force, and is coupled to a thermostat of temperature T. Within selected parameter regimes this system exhibits negative mobility, which means that the particle moves in the direction opposite to the direction of the constant force. It is known that in such a setup the inertial term is essential for the emergence of negative mobility and it cannot be detected in the limiting case of overdamped dynamics. We analyse inertial effects and show that negative mobility can be observed even in the strong damping regime. We determine the optimal dimensionless mass for the presence of negative mobility and reveal three mechanisms standing behind this anomaly: deterministic chaotic, thermal noise induced and deterministic non-chaotic. The last origin has never been reported. It may provide guidance to the possibility of observation of negative mobility for strongly damped dynamics which is of fundamental importance from the point of view of biological systems, all of which in situ operate in fluctuating environments.
Hydrogen-induced high damping of bulk metallic glasses
International Nuclear Information System (INIS)
Hasegawa, M.
2009-01-01
There are two important topics concerned with the recent researches on the damping materials of hydrogenated metallic glasses (HMGs). One is the mechanism of the high hydrogen-induced internal friction of HMGs. The other is the materials processing of 'bulk' HMGs for engineering. This article describes the summary of our recent studies on these topics. The first one is closely related to the local structure of the metallic glasses. Therefore, our recent results on the intermediate-range local structure of the simple two Zr-based metallic glasses are described, which has been clarified by the Voronoi analysis using the experimental data of the neutron diffraction measurements. The hydrogen-induced internal friction of HMGs is also discussed on the basis of these recent results of the local structure of the metallic glasses. In terms of the second topic, the first successful preparation of heavily hydrogenated Zr-based bulk HMG rods without hydrogen-induced surface embrittlement is described. They are prepared by a powder-compact-melting and liquid-casting process using Zr-Al-Ni-Cu metallic glass and ZrH 2 powders as the starting materials. It has been found that they have high damping properties.
Size effect related to damping caused by water submersion
International Nuclear Information System (INIS)
Dong, R.G.
1981-01-01
An important effect of water submersion on the dynamic response of a structure is the increase in effective damping. The dynamic response of submerged structures is of interest in the nuclear power industry for reasons of operational safety during seismic and other dynamic excitations. In this paper, the added damping contribution that results from the viscosity of water and the dependence of the contribution on structural size are examined. Other factors considered are the applicable range of viscous damping with respect to displacement amplitude and, as far as damping is concerned, how far neighboring members must be from each other to respond as if in open water. An expression is derived for relating the damping value to structural size. Estimated added-damping values for representative fuel elements, fuel bundles, and main steam-pressure-relief-valve lines are given based on our derived expression for added damping
Tuned mass absorbers on damped structures under random load
DEFF Research Database (Denmark)
Krenk, Steen; Høgsberg, Jan Becker
2008-01-01
the mass ratio alone, and the damping can be determined subsequently. Only approximate results are available for the influence of damping in the original structure, typically in the form of series expansions. In the present paper it is demonstrated that for typical mass ratios in the order of a few percent......A substantial literature exists on the optimal choice of parameters of a tuned mass absorber on a structure excited by a force or by ground acceleration with random characteristics in the form of white noise. In the absence of structural damping the optimal frequency tuning is determined from...... for the response variance of a structure with initial damping in terms of the mass ratio and both damping ratios. Within this format the optimal tuning of the absorber turns out to be independent of the structural damping, and a simple explicit expression is obtained for the equivalent total damping....
Power Oscillations Damping in DC Microgrids
DEFF Research Database (Denmark)
Hamzeh, Mohsen; Ghafouri, Mohsen; Karimi, Houshang
2016-01-01
This paper proposes a new control strategy for damping of power oscillations in a multi-source dc microgrid. A parallel combination of a fuel cell (FC), a photovoltaic (PV) system and a supercapacitor (SC) are used as a hybrid power conversion system (HPCS). The SC compensates for the slow transi...... of the proposed control scheme is verified using hardware-in-the-loop (HIL) simulations carried out in OPAL-RT technologies....
Multibunch resistive wall instability damping with feedback
International Nuclear Information System (INIS)
Zhabitskij, V.M.; Korenev, I.L.; Yudin, L.A.
1992-01-01
The theory of multibunch transverse resistive wall instability damping with feedback is development. The system of coupling equations is obtained for description of bunched beam motion. The general solution and eigen frequencies are found. But for two bunches or multi bunches the tune splitting is found. The band of the tune splitting is calculated. The influence of the tune splitting on the damper system stability is discussed. 14 refs
Collisional damping rates for plasma waves
Energy Technology Data Exchange (ETDEWEB)
Tigik, S. F., E-mail: sabrina.tigik@ufrgs.br; Ziebell, L. F., E-mail: luiz.ziebell@ufrgs.br [Instituto de Física, Universidade Federal do Rio Grande do Sul, 91501-970 Porto Alegre, Rio Grande do Sul (Brazil); Yoon, P. H., E-mail: yoonp@umd.edu [Institute for Physical Science and Technology, University of Maryland, College Park, Maryland 20742 (United States); School of Space Research, Kyung Hee University, Yongin, Gyeonggi 446-701 (Korea, Republic of)
2016-06-15
The distinction between the plasma dynamics dominated by collisional transport versus collective processes has never been rigorously addressed until recently. A recent paper [P. H. Yoon et al., Phys. Rev. E 93, 033203 (2016)] formulates for the first time, a unified kinetic theory in which collective processes and collisional dynamics are systematically incorporated from first principles. One of the outcomes of such a formalism is the rigorous derivation of collisional damping rates for Langmuir and ion-acoustic waves, which can be contrasted to the heuristic customary approach. However, the results are given only in formal mathematical expressions. The present brief communication numerically evaluates the rigorous collisional damping rates by considering the case of plasma particles with Maxwellian velocity distribution function so as to assess the consequence of the rigorous formalism in a quantitative manner. Comparison with the heuristic (“Spitzer”) formula shows that the accurate damping rates are much lower in magnitude than the conventional expression, which implies that the traditional approach over-estimates the importance of attenuation of plasma waves by collisional relaxation process. Such a finding may have a wide applicability ranging from laboratory to space and astrophysical plasmas.
Limitations of modal analysis of damped structures
International Nuclear Information System (INIS)
Krapf, K.G.; Woelfel, H.
1983-01-01
Quite recently discrete spring-damper elements are increasingly used for the low-tuned supports of nuclear power-plant buildings and equipment (reactor building, turbine-fundaments etc.) to reduce the vibration response due to the dynamic load cases earthquake and airplane crash. Because of this development, it is to be investigated whether the usual modal analysis method is applicable within the design process or should be changed respectively replaced in special cases. The paper contributes to this discussion by demonstrating and valuing the discrepancies in the different ways for the implementation of damping. Different methods for uncoupling (energy weighting, reduction to Rayleigh-damping) are compared with the solution of the coupled equations of motion. In particular vertical vibrations of a spring-damper-supported building on foundation (including ground springs) are examined using a two-degree-of-freedom-system. The results of coupled and (by force) uncoupled methods are interpreted concerning free vibration by comparison of the damping of natural vibrations, natural frequencies and natural mode shapes. The effect on the forced vibrations is shown by floor response spectra to an earthquake accelerogram. (orig./HP)
Landau damping in trapped Bose condensed gases
Energy Technology Data Exchange (ETDEWEB)
Jackson, B; Zaremba, E [Department of Physics, Queen' s University, Kingston, ON K7L 3N6 (Canada)
2003-07-01
We study Landau damping in dilute Bose-Einstein condensed gases in both spherical and prolate ellipsoidal harmonic traps. We solve the Bogoliubov equations for the mode spectrum in both of these cases, and calculate the damping by summing over transitions between excited quasiparticle states. The results for the spherical case are compared to those obtained in the Hartree-Fock (HF) approximation, where the excitations take on a single-particle character, and excellent agreement between the two approaches is found. We have also taken the semiclassical limit of the HF approximation and obtain a novel expression for the Landau damping rate involving the time-dependent self-diffusion function of the thermal cloud. As a final approach, we study the decay of a condensate mode by making use of dynamical simulations in which both the condensate and thermal cloud are evolved explicitly as a function of time. A detailed comparison of all these methods over a wide range of sample sizes and trap geometries is presented.
First Results from the DAMPE Mission
CERN. Geneva
2018-01-01
DAMPE (DArk Matter Particle Explorer) is a satellite mission of the Chinese Academy of Sciences (CAS) dedicated to high energy cosmic ray detections. Since its successful launch on December 17th, 2015 a large amount of cosmic ray data has been collected. With relatively large acceptance, DAMPE is designed to detect electrons (and positrons) up to 10 TeV with unprecedented energy resolution to search for new features in the cosmic ray electron plus positron (CRE) spectrum. It will also study cosmic ray nuclei up to 100 TeV with good precision, which will bring new input to the study of their still unknown origin and their propagation through the Galaxy. In this talk, the DAMPE mission will be introduced, together with some details of the construction and on-ground calibration of the detector subsystems. The in-orbit detector commissioning, calibration and operation will be described. First data analysis results, including the recently published CRE spectrum from 25 GeV to 4.6 TeV based on the data collected i...
DAMPs and influenza virus infection in ageing.
Samy, Ramar Perumal; Lim, Lina H K
2015-11-01
Influenza A virus (IAV) is a serious global health problem worldwide due to frequent and severe outbreaks. IAV causes significant morbidity and mortality in the elderly population, due to the ineffectiveness of the vaccine and the alteration of T cell immunity with ageing. The cellular and molecular link between ageing and virus infection is unclear and it is possible that damage associated molecular patterns (DAMPs) may play a role in the raised severity and susceptibility of virus infections in the elderly. DAMPs which are released from damaged cells following activation, injury or cell death can activate the immune response through the stimulation of the inflammasome through several types of receptors found on the plasma membrane, inside endosomes after endocytosis as well as in the cytosol. In this review, the detriment in the immune system during ageing and the links between influenza virus infection and ageing will be discussed. In addition, the role of DAMPs such as HMGB1 and S100/Annexin in ageing, and the enhanced morbidity and mortality to severe influenza infection in ageing will be highlighted. Copyright © 2015 Elsevier B.V. All rights reserved.
Etiology of root parsley damping-off
Directory of Open Access Journals (Sweden)
Bogdan Nowicki
2013-12-01
Full Text Available The investigations were done between 1990-1994. Seedlings collected from 120 plantations were evaluated. The fungi responsible for seedling damping-off occurrening most often were Alternariu spp., Fusarium spp. and Pythium spp. isolated from 46,3, 32,2 and 16,6% of infected plants, respectively. The most important pathogens were A.petroselini which infected 33% of seedlings and A.radicina - 11%„ Among Fusarium species the most common was F.avenaceum, comprising 61% of total Fusarium isolates. The next were following: F.culmorum - 21%, F.solani - 12,6% and 3% for both F.equiseti and F.oxysporum. Damping-off of se,edlings was also caused by the other fungi but they were noted in low intensity. Among them were following: Phoma spp., A.alternata and Rhizoctonia solani on 2,8; 2,3 and 1,2% of tested seedlings. respectively. The species: Sclerotinia sclerotiorum, Botrytis cinerea, Bipolaris sorokinianu and Septoria petroselini were isolated in total from 0,9% of seedlings. Drechslera biseptata and Stemphylium botryosum caused seedling damping-off sporadically.
Possibility of Landau damping of gravitational waves
International Nuclear Information System (INIS)
Gayer, S.; Kennel, C.F.
1979-01-01
There is considerable uncertainty in the literature concerning whether or not transverse traceless gravitational waves can Landau damp. Physically, the issue is whether particles of nonzero mass can comove with surfaces of constant wave phase, and therefore, loosely, whether gravitational waves can have phase speeds less than that of light. We approach the question of Landau damping in various ways. We consider first the propagation of small-amplitude gravitational waves in an ideal fluid-filled Robertson-Walker universe of zero spatial curvature. We argue that the principle of equivalence requires those modes to be lightlike. We show that a freely moving particle interacting only with the collective fields cannot comove with such waves if it has nonzero mass. The equation for gravitational waves in collisionless kinetic gases differs from that for fluid media only by terms so small that deviations from lightlike propagation are unmeasurable. Thus, we conclude that Landau damping of small-amplitude, transverse traceless gravitational waves is not possible
Radiative damping in plasma-based accelerators
Directory of Open Access Journals (Sweden)
I. Yu. Kostyukov
2012-11-01
Full Text Available The electrons accelerated in a plasma-based accelerator undergo betatron oscillations and emit synchrotron radiation. The energy loss to synchrotron radiation may seriously affect electron acceleration. The electron dynamics under combined influence of the constant accelerating force and the classical radiation reaction force is studied. It is shown that electron acceleration cannot be limited by radiation reaction. If initially the accelerating force was stronger than the radiation reaction force, then the electron acceleration is unlimited. Otherwise the electron is decelerated by radiative damping up to a certain instant of time and then accelerated without limits. It is shown that regardless of the initial conditions the infinite-time asymptotic behavior of an electron is governed by a self-similar solution providing that the radiative damping becomes exactly equal to 2/3 of the accelerating force. The relative energy spread induced by the radiative damping decreases with time in the infinite-time limit. The multistage schemes operating in the asymptotic acceleration regime when electron dynamics is determined by the radiation reaction are discussed.
International Nuclear Information System (INIS)
Bachmann, F; Delpero, T; Ermanni, P; De Oliveira, R; Sigg, A; Michaud, V; Schnyder, V; Jaehne, R; Bergamini, A
2012-01-01
Emission reduction from civil aviation has been intensively addressed in the scientific community in recent years. The combined use of novel aircraft engine architectures such as open rotor engines and lightweight materials offer the potential for fuel savings, which could contribute significantly in reaching gas emissions targets, but suffer from vibration and noise issues. We investigated the potential improvement of mechanical damping of open rotor composite fan blades by comparing two integrated passive damping systems: shape memory alloy wires and piezoelectric shunt circuits. Passive damping concepts were first validated on carbon fibre reinforced epoxy composite plates and then implemented in a 1:5 model of an open rotor blade manufactured by resin transfer moulding (RTM). A two-step process was proposed for the structural integration of the damping devices into a full composite fan blade. Forced vibration measurements of the plates and blade prototypes quantified the efficiency of both approaches, and their related weight penalty. (paper)
Bachmann, F.; de Oliveira, R.; Sigg, A.; Schnyder, V.; Delpero, T.; Jaehne, R.; Bergamini, A.; Michaud, V.; Ermanni, P.
2012-07-01
Emission reduction from civil aviation has been intensively addressed in the scientific community in recent years. The combined use of novel aircraft engine architectures such as open rotor engines and lightweight materials offer the potential for fuel savings, which could contribute significantly in reaching gas emissions targets, but suffer from vibration and noise issues. We investigated the potential improvement of mechanical damping of open rotor composite fan blades by comparing two integrated passive damping systems: shape memory alloy wires and piezoelectric shunt circuits. Passive damping concepts were first validated on carbon fibre reinforced epoxy composite plates and then implemented in a 1:5 model of an open rotor blade manufactured by resin transfer moulding (RTM). A two-step process was proposed for the structural integration of the damping devices into a full composite fan blade. Forced vibration measurements of the plates and blade prototypes quantified the efficiency of both approaches, and their related weight penalty.
Ottander, John A.; Hall, Robert A.; Powers, J. F.
2018-01-01
A method is presented that allows for the prediction of the magnitude of limit cycles due to adverse control-slosh interaction in liquid propelled space vehicles using non-linear slosh damping. Such a method is an alternative to the industry practice of assuming linear damping and relying on: mechanical slosh baffles to achieve desired stability margins; accepting minimal slosh stability margins; or time domain non-linear analysis to accept time periods of poor stability. Sinusoidal input describing functional analysis is used to develop a relationship between the non-linear slosh damping and an equivalent linear damping at a given slosh amplitude. In addition, a more accurate analytical prediction of the danger zone for slosh mass locations in a vehicle under proportional and derivative attitude control is presented. This method is used in the control-slosh stability analysis of the NASA Space Launch System.
International Nuclear Information System (INIS)
Perfetto, S; Rohlfing, J; Infante, F; Mayer, D; Herold, S
2016-01-01
Piezoelectric transducers can be used to harvest electrical energy from structural vibrations in order to power continuously operating condition monitoring systems local to where they operate. However, excessive vibrations can compromise the safe operation of mechanical systems. Therefore, absorbers are commonly used to control vibrations. With an integrated device, the mechanical energy that otherwise would be dissipated can be converted via piezoelectric transducers. Vibration absorbers are designed to have high damping factors. Hence, the integration of transducers would lead to a low energy conversion. Efficient energy harvesters usually have low damping capabilities; therefore, they are not effective for vibration suppression. Thus, the design of an integrated device needs to consider the two conflicting requirements on the damping. This study focuses on the development of a laboratory test rig with a host structure and a vibration absorber with tunable damping via an active relative velocity feedback. A voice coil actuator is used for this purpose. To overcome the passive damping effects of the back electromagnetic force a novel voltage feedback control is proposed, which has been validated both in simulation and experimentally. The aim of this study is to have a test rig ready for the introduction of piezo-transducers and available for future experimental evaluations of the damping effect on the effectiveness of vibration reduction and energy harvesting efficiency. (paper)
Perfetto, S.; Rohlfing, J.; Infante, F.; Mayer, D.; Herold, S.
2016-09-01
Piezoelectric transducers can be used to harvest electrical energy from structural vibrations in order to power continuously operating condition monitoring systems local to where they operate. However, excessive vibrations can compromise the safe operation of mechanical systems. Therefore, absorbers are commonly used to control vibrations. With an integrated device, the mechanical energy that otherwise would be dissipated can be converted via piezoelectric transducers. Vibration absorbers are designed to have high damping factors. Hence, the integration of transducers would lead to a low energy conversion. Efficient energy harvesters usually have low damping capabilities; therefore, they are not effective for vibration suppression. Thus, the design of an integrated device needs to consider the two conflicting requirements on the damping. This study focuses on the development of a laboratory test rig with a host structure and a vibration absorber with tunable damping via an active relative velocity feedback. A voice coil actuator is used for this purpose. To overcome the passive damping effects of the back electromagnetic force a novel voltage feedback control is proposed, which has been validated both in simulation and experimentally. The aim of this study is to have a test rig ready for the introduction of piezo-transducers and available for future experimental evaluations of the damping effect on the effectiveness of vibration reduction and energy harvesting efficiency.
Energy Technology Data Exchange (ETDEWEB)
Rubio, E. M.; Domingo, R.; Gonzalez, C.; Sanz, A.
2004-07-01
To study the optimised geometrical configuration to carry out mechanical drawing of plates is the main objective of this paper. To accomplish this objective, a comparative analysis of some suitable geometrical and kinematic configurations of the material located in the deformation zone has been made. Concretely, several triangular rigid zone models have been chosen, for each one, the overall energy involved in the process have been calculated and an estimation of its different components has been made. The calculation of the energy has been achieved applying the Upper Bound Theorem under plane strain and partial friction conditions. In addition, the range of use for the selected configurations has been established. (Author) 19 refs.
International Nuclear Information System (INIS)
Phuoc, Le Minh; Lee, Suk Han; Kim, Hun Mo; Martinet, Philippe
2008-01-01
Robot inverse kinematics based on Jacobian inversion encounters critical issues of kinematic singularities. In this paper, several techniques based on damped least squares are proposed to lead robot pass through kinematic singularities without excessive joint velocities. Unlike other work in which the same damping factor is used for all singular vectors, this paper proposes a different damping coefficient for each singular vector based on corresponding singular value of the Jacobian. Moreover, a continuous distribution of damping factor following Gaussian function guarantees the continuous in joint velocities. A genetic algorithm is utilized to search for the best maximum damping factor and singular region, which used to require ad hoc searching in other works. As a result, end effector tracking error, which is inherited from damped least squares by introducing damping factors, is minimized. The effectiveness of our approach is compared with other methods in both non-redundant robot and redundant robot
Energy Technology Data Exchange (ETDEWEB)
Phuoc, Le Minh; Lee, Suk Han; Kim, Hun Mo [Sungkyunkwan University, Suwon (Korea, Republic of); Martinet, Philippe [Blaise Pascal University, Clermont-Ferrand Cedex (France)
2008-07-15
Robot inverse kinematics based on Jacobian inversion encounters critical issues of kinematic singularities. In this paper, several techniques based on damped least squares are proposed to lead robot pass through kinematic singularities without excessive joint velocities. Unlike other work in which the same damping factor is used for all singular vectors, this paper proposes a different damping coefficient for each singular vector based on corresponding singular value of the Jacobian. Moreover, a continuous distribution of damping factor following Gaussian function guarantees the continuous in joint velocities. A genetic algorithm is utilized to search for the best maximum damping factor and singular region, which used to require ad hoc searching in other works. As a result, end effector tracking error, which is inherited from damped least squares by introducing damping factors, is minimized. The effectiveness of our approach is compared with other methods in both non-redundant robot and redundant robot
ANALISIS VARIABEL KEUANGAN YANG MEMPENGARUHI KEBIJAKAN DEVIDEN
Directory of Open Access Journals (Sweden)
Sumiadji -
2012-03-01
Full Text Available Penelitian ini dilakukan untuk menguji pengaruh variabel keuangan yang terdiri dari: rasio pro-fitabilitas (return on assets, likuiditas (cash ratio, rasio hutang (debt to equity ratio, market value (earnings per share, dan perputaran total aset (total assets turnover terhadap kebijakan dividen yang diproksikan dengan dividend payout ratio (DPR pada perusahaan manufaktur yang terdaftar di Bursa Efek Indonesia tahun 2004-2008. Prosedur pemilihan sampel penelitian menggunakan purposive sampling sehingga menghasilkan 8 perusahaan yang memenuhi kriteria sampel. Data sekunder dikumpulkan dengan teknik dokumentasi bersumber dari Indonesian Capital Market Directory (ICMD, laporan keuangan, dan hasil Rapat Umum Pemegang Saham (RUPS. Teknik analisis yang digunakan dalam penelitian ini adalah analisis regresi linear berganda. Hasil penelitian ini adalah secara simultan variabel ROA, CR, DER, EPS dan TATO berpengaruh terhadap DPR. Secara parsial variabel yang mempengaruhi DPR adalah CR, EPS dan TATO. Varabel lainnya, yaitu ROA dan DER ditemukan tidak berpengaruh terhadap DPR.Â This research was conducted to examine the influence of the financial variables which consists of: return on assets (ROA, cash ratio (CR, debt to equity ratio (DER, earnings per share (EPS, and total asset turnover (TATO to the dividend policy that indicated by the dividend payout ratio (DPR of listed manufacturing company in Indonesia Stock Exchange Â 2004 to 2008. The sample selection procedure used was a purposive sampling so that it produced eight companies that met the sample criteria. Se-condary data was collected by the documentation technique were obtained from the Indonesian Capital Market Directory (ICMD, financial statements, and the results of the Annual General Meeting of Shareholders. The analysis technique used was multiple linear regression analysis. The research found that five variables of kind of ROA, CR, DER, EPS dan TATO simultaneously influence to dividend
International Nuclear Information System (INIS)
Pradeep, R. Gladwin; Chandrasekar, V. K.; Senthilvelan, M.; Lakshmanan, M.
2009-01-01
In this paper we point out the existence of a remarkable nonlocal transformation between the damped harmonic oscillator and a modified Emden-type nonlinear oscillator equation with linear forcing, xe+αxx+βx 3 +γx=0, which preserves the form of the time independent integral, conservative Hamiltonian, and the equation of motion. Generalizing this transformation we prove the existence of nonstandard conservative Hamiltonian structure for a general class of damped nonlinear oscillators including Lienard-type systems. Further, using the above Hamiltonian structure for a specific example, namely, the generalized modified Emden equation xe+αx q x+βx 2q+1 =0, where α, β, and q are arbitrary parameters, the general solution is obtained through appropriate canonical transformations. We also present the conservative Hamiltonian structure of the damped Mathews-Lakshmanan oscillator equation. The associated Lagrangian description for all the above systems is also briefly discussed.
Energy Technology Data Exchange (ETDEWEB)
Hernandez L, H; Ortiz V, J [ININ, 52045 Ocoyoacac, Estado de Mexico (Mexico)
2003-07-01
In the National Institute of Nuclear Research of Mexico a code for the thermo-mechanical analysis of the fuel rods of the BWR type reactors of the Nucleo electric Central of Laguna Verde is developed. The code solves the diffusion equation in cylindrical coordinates with several energy groups. The code, likewise, calculates the temperature distribution and power distribution in those fuel rods. The code is denominated Multi groups With Temperatures and Power (MCTP). In the code, the energy with which the fission neutrons are emitted it is divided in six groups. They are also considered the produced perturbations by the changes in the temperatures of the materials that constitute the fuel rods, the content of fission products, the uranium consumption and in its case the gadolinium, as well as the plutonium production. In this work there are present preliminary results obtained with the code, using data of operation of the Nucleo electric Central of Laguna Verde. (Author)
Damping in building structures during earthquakes: test data and modeling
International Nuclear Information System (INIS)
Coats, D.W. Jr.
1982-01-01
A review and evaluation of the state-of-the-art of damping in building structures during earthquakes is presented. The primary emphasis is in the following areas: 1) the evaluation of commonly used mathematical techniques for incorporating damping effects in both simple and complex systems; 2) a compilation and interpretation of damping test data; and 3) an evaluation of structure testing methods, building instrumentation practices, and an investigation of rigid-body rotation effects on damping values from test data. A literature review provided the basis for evaluating mathematical techiques used to incorporate earthquake induced damping effects in simple and complex systems. A discussion on the effectiveness of damping, as a function of excitation type, is also included. Test data, from a wide range of sources, has been compiled and interpreted for buidings, nuclear power plant structures, piping, equipment, and isolated structural elements. Test methods used to determine damping and frequency parameters are discussed. In particular, the advantages and disadvantages associated with the normal mode and transfer function approaches are evaluated. Additionally, the effect of rigid-body rotations on damping values deduced from strong-motion building response records is investigated. A discussion of identification techniques typically used to determine building parameters (frequency and damping) from strong motion records is included. Finally, an analytical demonstration problem is presented to quantify the potential error in predicting fixed-base structural frequency and damping values from strong motion records, when rigid-body rotations are not properly accounted for
Foucault pendulum with eddy-current damping of the elliptical motion
Mastner, G.; Vokurka, V.; Maschek, M.; Vogt, E.; Kaufmann, H. P.
1984-10-01
A newly designed Foucault pendulum is described in which the mechanical Charron ring, used throughout in previous designs for damping of the elliptical motion of the pendulum, is replaced by an electromagnetic eddy-current brake, consisting of a permanent magnet attached to the bottom of the bob and a metallic ring. This damping device is very efficient, as it is self-aligning, symmetrical in the damping effect, and never wears out. The permanent magnet is also used, together with a coil assembly and an electronic circuitry, for the dipole-torque drive of the pendulum as well as for accurate stabilization of the amplitude of the swing. A latched time display, controlled by Hall probes activated by the magnet, is used to visualize the Foucault rotation. The pendulum system and its associated electronic circuitry are described in detail. The optimizing of the drive mode is discussed. Measurements of deviations from theoretical value of the Foucault rotation velocity made automatically in a continuous run show a reproducible accuracy of ±1% or better in individual 360° rotations during the summer months. The quality factor of the pendulum as mechanical resonator was measured as a function of the amplitude in the presence of the eddy-current damping ring.
On the origin of nonlocal damping in plasmonic monomers and dimers
Tserkezis, Christos; Yan, Wei; Hsieh, Wenting; Sun, Greg; Khurgin, Jacob B.; Wubs, Martijn; Mortensen, N. Asger
2017-09-01
The origin and importance of nonlocal damping is discussed through simulations with the generalized nonlocal optical response (GNOR) theory, in conjunction with time-dependent density functional theory (TDDFT) calculations and equivalent circuit modeling, for some of the most typical plasmonic architectures: metal-dielectric interfaces, metal-dielectric-metal gaps, spherical nanoparticles and nanoparticle dimers. It is shown that diffusive damping, as introduced by the convective-diffusive GNOR theory, describes well the enhanced losses and plasmon broadening predicted by ab initio calculations in few-nm particles or few-to-sub-nm gaps. Through the evaluation of a local effective dielectric function, it is shown that absorptive losses appear dominantly close to the metal surface, in agreement with TDDFT and the mechanism of Landau damping due to generation of electron-hole pairs near the interface. Diffusive nonlocal theories provide therefore an efficient means to tackle plasmon damping when electron tunneling can be safely disregarded, without the need to resort to more accurate, but time-consuming fully quantum-mechanical studies.
CORONAL DENSITY STRUCTURE AND ITS ROLE IN WAVE DAMPING IN LOOPS
Energy Technology Data Exchange (ETDEWEB)
Cargill, P. J. [Space and Atmospheric Physics, The Blackett Laboratory, Imperial College, London SW7 2BW (United Kingdom); De Moortel, I.; Kiddie, G., E-mail: p.cargill@imperial.ac.uk [School of Mathematics and Statistics, University of St Andrews, St Andrews, Scotland KY16 9SS (United Kingdom)
2016-05-20
It has long been established that gradients in the Alfvén speed, and in particular the plasma density, are an essential part of the damping of waves in the magnetically closed solar corona by mechanisms such as resonant absorption and phase mixing. While models of wave damping often assume a fixed density gradient, in this paper the self-consistency of such calculations is assessed by examining the temporal evolution of the coronal density. It is shown conceptually that for some coronal structures, density gradients can evolve in a way that the wave-damping processes are inhibited. For the case of phase mixing we argue that (a) wave heating cannot sustain the assumed density structure and (b) inclusion of feedback of the heating on the density gradient can lead to a highly structured density, although on long timescales. In addition, transport coefficients well in excess of classical are required to maintain the observed coronal density. Hence, the heating of closed coronal structures by global oscillations may face problems arising from the assumption of a fixed density gradient, and the rapid damping of oscillations may have to be accompanied by a separate (non-wave-based) heating mechanism to sustain the required density structuring.
Energy Technology Data Exchange (ETDEWEB)
Campos Amezcua, Alfonso
2007-04-15
). This interface allows integrating the computational models virtually, although they have different grids, and that the CFD model registers the data in center cells, whereas the FEA model registers them in the nodes. Pressure, temperature and velocity profiles were obtained for the fluid and, temperature and stress for the solid. The obtained results are compared with experimental data reported in literature obtaining acceptable results. With this work, information for complementary studies is generated, as failure analysis faults and blade life assessment. [Spanish] Este trabajo presenta una metodologia para el analisis termomecanico de un alabe de turbina de gas con enfriamiento interno, la cual permite eliminar simplificaciones tipicas en este tipo de estudios, tales como: analisis ensamblados de perfiles bidimensionales, que desprecia los efectos tridimensionales del flujo que rodea la punta del alabe entre otras zonas; uso de coeficientes de transferencia de calor semi-empiricos obtenidos de predicciones de flujo adiabatico, entre otros. Esta metodologia utiliza dinamica de fluidos computacional ((CFD) por sus siglas en ingles) para el analisis de flujo y transferencia de calor conjugado y, analisis por elementos finitos ((FEA) por sus siglas en ingles) para el analisis termoestructural, estas tecnicas de simulacion han llegado a ser herramientas estandar para cada uno de los analisis, pero su integracion virtual aun esta en proceso de desarrollo. El codigo de CFD utiliza las ecuaciones de conservacion, asi como ecuaciones constitutivas adicionales para los diversos fenomenos que se presentan, permitiendo utilizar funciones definidas por el usuario para utilizar condiciones de frontera dinamicas en el analisis transitorio y propiedades variables de los materiales, lo cual incrementa la presion de las predicciones. Para resolver las ecuaciones y encontrar una solucion aproximada, se utiliza el metodo de volumen finito. Por otro lado, el codigo de FEA utiliza las
Investigation of Squeeze Film Damping and Associated Loads
DEFF Research Database (Denmark)
Johansen, Per; Bender, Niels Christian; Hansen, Anders Hedegaard
2017-01-01
-viscous case. In consequence, this enable insights concerning the influence of piezo-viscosity on this damping effect. These models are used to investigate the loads, which the approaching surfaces experiences. Based on Hertzian theory, comparisons of impact loads and the dynamic squeeze loading are performed......Digital hydraulics have attracted attention towards fast switching valves and the increased focus on reliable fluid power entail that the lifetime of such valves is of great concern. An inherent feature of most valves for digital hydraulics is that of a mechanical end stop. Consequently...... is reviewed with a focus on maximum surface stresses. Using the Barus relation for viscosity-pressure dependency and different film geometries, the classical lubrication theory is applied together with the equation of motion, to obtain the gap height motion equation, both for the iso-viscous and piezo...
ANALISIS VARIABILITAS CURAH HUJAN DAN SUHU DI BALI
Directory of Open Access Journals (Sweden)
Ogi Setiawan
2017-01-01
Full Text Available Indonesia sebagai negara kepulauan yang terdiri dari pulau-pulau besar dan kecil menjadi sangat rentan terhadap dampak perubahan iklim. Salah satu pulau yang juga rentan terhadap perubahan iklim adalah pulau Bali. Dampak potensial adanya perubahan iklim adalah perubahan pola hujan, peningkatan suhuudaradankenaikanpermukaanlaut. Sektoryangakanmenerimadampakperubahaniklimdengan serius adalah sektor kehutanan dan pertanian. Untuk mendukung upaya mitigasi dan adaptasi maka diperlukan informasi perubahan iklim yang terjadi. Penelitian ini bertujuan untuk mengetahui variabilitas iklim di Bali. Metode yang digunakan adalah analisis kecenderungan curah hujan, analisis perubahan suhu udara, analisis perubahan tipe iklim dan analisis pergeseran bulan basah, lembab dan kering. Data hujan yang digunakan adalah data hujan dari GPCC (1961-1998 dan BMKG Bali (19992008, sedangkan data suhu berasal dari BMKG Bali (2004-2008. Hasil analisis menunjukkan bahwa di pulau Bali secara umum sudah mengalami perubahan iklim. Tipe iklim berdasarkan Schmidt-Ferguson mengalami perubahan dari relatif basah menjadi agak kering. Suhu udara rata-rata bulanan serta curah hujan bulanan dan tahunan memiliki kecenderungan yang semakin meningkat. Bulan basah dan bulan kering telah mengalami pergeseran dan perubahan jumlahnya. Dampak perubahan iklim terhadap ekosistem hutan di Bali belum diketahui dengan pasti, namun terdapat beberapa implikasi perubahan iklim terhadap sektor kehutanan diantaranya kebakaran hutan dan perubahan jadwal penanaman.
Digital notch filter based active damping for LCL filters
DEFF Research Database (Denmark)
Yao, Wenli; Yang, Yongheng; Zhang, Xiaobin
2015-01-01
. In contrast, the active damping does not require any dissipation elements, and thus has become of increasing interest. As a result, a vast of active damping solutions have been reported, among which multi-loop control systems and additional sensors are necessary, leading to increased cost and complexity....... In this paper, a notch filter based active damping without the requirement of additional sensors is proposed, where the inverter current is employed as the feedback variable. Firstly, a design method of the notch filter for active damping is presented. The entire system stability has then been investigated...... in the z-domain. Simulations and experiments are carried out to verify the proposed active damping method. Both results have confirmed that the notch filter based active damping can ensure the entire system stability in the case of resonances with a good system performance....
Controlled damping of a physical pendulum: experiments near critical conditions
International Nuclear Information System (INIS)
Gonzalez, Manuel I; Bol, Alfredo
2006-01-01
This paper presents an experimental device for the study of damped oscillatory motion along with three associated experiments. Special emphasis is given on both didactic aspects and the interactivity of the experimental set-up, in order to assist students in understanding fundamental aspects of damped oscillatory motion and allow them to directly compare their experimental results with the well-known theory they can find in textbooks. With this in mind, a physical pendulum was selected with an eddy-current damping system that allows the damping conditions to be controlled with great precision. The three experiments examine accurate control of damping, frequency shift near critical damping and the transition from underdamped to overdamped conditions
Special class of nonlinear damping models in flexible space structures
Hu, Anren; Singh, Ramendra P.; Taylor, Lawrence W.
1991-01-01
A special class of nonlinear damping models is investigated in which the damping force is proportional to the product of positive integer or the fractional power of the absolute values of displacement and velocity. For a one-degree-of-freedom system, the classical Krylov-Bogoliubov 'averaging' method is used, whereas for a distributed system, both an ad hoc perturbation technique and the finite difference method are employed to study the effects of nonlinear damping. The results are compared with linear viscous damping models. The amplitude decrement of free vibration for a single mode system with nonlinear models depends not only on the damping ratio but also on the initial amplitude, the time to measure the response, the frequency of the system, and the powers of displacement and velocity. For the distributed system, the action of nonlinear damping is found to reduce the energy of the system and to pass energy to lower modes.
Magnon damping in two-dimensional Heisenberg ferromagnetic system
International Nuclear Information System (INIS)
Cheng, T.-M.; Li Lin; Ze Xianyu
2006-01-01
A magnon-phonon interaction model is set up for a two-dimensional insulating ferromagnetic system. By using Matsubara function theory we have studied the magnon damping -I m Σ* (1) (k->) and calculated the magnon damping -I m Σ* (1) (k->) curve on the main symmetric point and line in the Brillouin zone for various parameters in the system. It is concluded that at the boundary of Brillouin zone there is a strong magnon damping. However, the magnon damping is very weak on the zone of small wave vector and the magnon damping reaches maximal value at very low temperature. The contributions of longitudinal phonon and transverse phonon on the magnon damping are compared and the influences of various parameters are also discussed
Collisional damping of Langmuir waves in the collisionless limit
International Nuclear Information System (INIS)
Auerbach, S.P.
1977-01-01
Linear Langmuir wave damping by collisions is studied in the limit of collision frequency ν approaching zero. In this limit, collisions are negligible, except in a region in velocity space, the boundary layer, centered about the phase velocity. If kappa, the ratio of the collisional equilibration time in the boundary layer to the Landau damping time, is small, the boundary layer width scales as ν/sup 1/3/, and the perturbed distribution function scales as ν/sup -1/3/. The damping rate is thus independent of ν, although essentially all the damping occurs in the collision-dominated boundary layer. Solution of the Fokker--Planck equation shows that the damping rate is precisely the Landau (collisionless) rate. The damping rate is independent of kappa, although the boundary layer thickness is not
An experimental study on damping characteristics of thermal insulation
International Nuclear Information System (INIS)
Chiba, Toshio; Kobayashi, Hiroe; Aida, Shigekazu; Wada, Hidetoshi
1984-01-01
The damping ratio is one of the most important parameters in seismic analysis of piping systems in a nuclear power plant. Thermal insulation is considered contributing to the damping characteristics of piping systems. At the 6th SMiRT and 1983 ASME PVP conferences, the damping effect and damping estimating formula were presented as a result of regression analysis using the component test data for 2,4 and 8B diameter piping and the proof model test for 1,2 and 4B piping system. In this study, in order to clarify the damping characteristics of a larger diameter piping than 8B,the component test of 12 and 20B diameter piping with insulation was performed. From the results of these tests and the data survey of the previous papers, it was found that the damping ratio of anactual piping system with thermal insulation is at minimum 1% for all size diameter piping. (author)
An experimental study on damping characteristics of thermal insulation
International Nuclear Information System (INIS)
Chiba, T.; Kobayashi, H.
1985-01-01
The damping ratio is one of the most important parameters in seismic analysis of nuclear power plant piping systems. Thermal Insulation is considered to contribute to the damping characteristics of piping systems. In the 6th SMiRT conference and 1983 ASME PVP, the damping effect and damping estimating formula was presented as a result of regression analysis from the component tests of 2'' , 4'', and 8'' diameter piping and the proof model test of 1'', 2'' and 4'' piping. In this study, in order to clarify the damping characteristics of larger diameter piping than 8'', the component test of 12'' and 20'' diameter piping with insulation was performed. From the results of these tests and the data survey of the previous papers it was found that the damping ratio of actual piping system with thermal insulation is at least 1% for all size diameter piping
Oscillation damping of chiral string loops
International Nuclear Information System (INIS)
Babichev, Eugeny; Dokuchaev, Vyacheslav
2002-01-01
Chiral cosmic string loops tend to the stationary (vorton) configuration due to energy loss into gravitational and electromagnetic radiation. We describe the asymptotic behavior of near stationary chiral loops and their fading to vortons. General limits on the gravitational and electromagnetic energy losses by near stationary chiral loops are found. For these loops we estimate the oscillation damping time. We present solvable examples of gravitational radiation energy loss by some chiral loop configurations. The analytical dependence of string energy with time is found in the case of the chiral ring with small amplitude radial oscillations
Power Oscillations Damping in DC Microgrids
Hamzeh, Mohsen; Ghafouri, Mohsen; Karimi, Houshang; Sheshyekani, Keyhan; Guerrero, Josep M.
2016-01-01
This paper proposes a new control strategy for damping of power oscillations in a multi-source dc microgrid. A parallel combination of a fuel cell (FC), a photovoltaic (PV) system and a supercapacitor (SC) are used as a hybrid power conversion system (HPCS). The SC compensates for the slow transient response of the FC stack. The HPCS controller comprises a multi-loop voltage controller and a virtual impedance loop for power management. The virtual impedance loop uses a dynamic droop gain to a...
Hyperchaotic circuit with damped harmonic oscillators
DEFF Research Database (Denmark)
Lindberg, Erik; Murali, K.; Tamasevicius, A.
2001-01-01
A simple fourth-order hyperchaotic circuit with damped harmonic oscillators is described. ANP3 and PSpice simulations including an eigenvalue study of the linearized Jacobian are presented together with a hardware implementation. The circuit contains two inductors with series resistance, two ideal...... capacitors and one nonlinear active conductor. The Lyapunov exponents are presented to confirm the hyperchaotic nature of the oscillations of the circuit. The nonlinear conductor is realized with a diode. A negative impedance converter and a linear resistor. The performance of the circuit is investigated...... by means of numerical integration of the appropriate differential equations....
System for damping vibrations in a turbine
Roberts, III, Herbert Chidsey; Johnson, Curtis Alan; Taxacher, Glenn Curtis
2015-11-24
A system for damping vibrations in a turbine includes a first rotating blade having a first ceramic airfoil, a first ceramic platform connected to the first ceramic airfoil, and a first root connected to the first ceramic platform. A second rotating blade adjacent to the first rotating blade includes a second ceramic airfoil, a second ceramic platform connected to the second ceramic airfoil, and a second root connected to the second ceramic platform. A non-metallic platform damper has a first position in simultaneous contact with the first and second ceramic platforms.
Status of the SLC damping rings
International Nuclear Information System (INIS)
Hutton, A.M.; Davies-White, W.A.; Delahaye, J.P.
1985-06-01
Electron beams of full design energy 1.21 GeV and nearly full design intensity 4 x 10 10 particles/pulse (design 5 x 10 10 ) have been extracted from the Stanford Linac and successfully stored in the electron damping ring. Beams of less intensity have been extracted from the ring and reinjected into the Linac. The present intensity limits are not thought to be fundamental. The operating experience with the electron ring and the status of the construction of the positron ring will be discussed. 11 refs., 1 fig., 2 tabs
Coherent Synchrotron Radiation effect in damping rings
International Nuclear Information System (INIS)
Raubenheimer, T
2004-01-01
Coherent Synchrotron Radiation (CSR) can play an important role by not only increasing the energy spread and emittance of a beam, but also leading to a potential instability. Previous studies of the CSR induced longitudinal instability were carried out for the CSR impedance due to dipole magnets. In this paper, the instability due to the CSR impedance from a wiggler is studied assuming a large wiggler parameter K. The primary consideration is a low frequency microwave-like instability in the damping rings of several linear collider projects. The threshold is determined by the instability with the longest possible wavelength
Thermal equilibrium in strongly damped collisions
International Nuclear Information System (INIS)
Samaddar, S.K.; De, J.N.; Krishan, K.
1985-01-01
Energy division between colliding nuclei in damped collisions is studied in the statistical nucleon exchange model. The reactions 56 Fe+ 165 Ho and 56 Fe+ 238 U at incident energy of 465 MeV are considered for this purpose. It is found that the excitation energy is approximately equally shared between the nuclei for the peripheral collisions and the systems slowly approach equilibrium for more central collisions. This is in conformity with the recent experimental observations. The calculated variances of the charge distributions are found to depend appreciably on the temperature and are in very good agreement with the experimental data
Confirmation of soil radiation damping from test versus analysis
International Nuclear Information System (INIS)
Eidinger, J.M.; Mukhim, G.S.; Desmond, T.P.
1987-01-01
The work was performed to demonstrate that soil-structure interaction effects for nuclear plant structures can be accurately (and conservatively) predicted using the finite element or soil spring methods of soil-structure interaction analysis. Further, the work was done to investigate the relative importance of soil radiation versus soil material damping in the total soil damping analytical treatment. The analytical work was benchmarked with forced vibration tests of a concrete circular slab resting on the soil surface. The applied loading was in the form of a suddenly applied pulse load, or snapback. The measured responses of the slap represent the free vibration of the slab after the pulse load has been applied. This simplifies the interpretation of soil damping, by the use of the logarithmic decay formulation. To make comparisons with the test results, the damping data calculated from the analytical models is also based on the logarithmic decay formulation. An attempt is made to differentiate the observed damped behavior of the concrete slab as being caused by soil radiation versus soil material damping. It is concluded that both the traditional soil radiation and material damping analytical simplifications are validated by the observed responses. It is concluded that arbitrary 'conservative' assumptions traditionally made in nuclear plant soil-structure interaction analyses are indeed arbitrary, and not born out by physical evidence. The amount of conservatism introduced by limiting total soil damping to values like 5% to 10% can be large. For the test slab sizes investigated, total soil damping is about 25%. For full size nuclear plant foundations, total soil damping is commonly in the 35% to 70% range. The authors suggest that full soil damping values (the combined radiation and material damping) should be used in the design, backfit and margin assessment of nuclear plants. (orig./HP)
Rising damp in building walls: the wall base ventilation system
Energy Technology Data Exchange (ETDEWEB)
Guimaraes, A.S.; Delgado, J.M.P.Q.; Freitas, V.P. de [Faculdade de Engenharia da Universidade do Porto, Laboratorio de Fisica das Construcoes (LFC), Departamento de Engenharia Civil, Porto (Portugal)
2012-12-15
This work intends to validate a new system for treating rising damp in historic buildings walls. The results of laboratory experiments show that an efficient way of treating rising damp is by ventilating the wall base, using the HUMIVENT technique. The analytical model presented describes very well the observed features of rising damp in walls, verified by laboratory tests, who contributed for a simple sizing of the wall base ventilation system that will be implemented in historic buildings. (orig.)
Complex modes and frequencies in damped structural vibrations
DEFF Research Database (Denmark)
Krenk, Steen
2004-01-01
It is demonstrated that the state space formulation of the equation of motion of damped structural elements like cables and beams leads to a symmetric eigenvalue problem if the stiffness and damping operators are self-adjoint, and that this is typically the case in the absence of gyroscopic forces....... The corresponding theory of complex modal analysis of continuous systems is developed and illustrated in relation to optimal damping and impulse response of cables and beams with discrete dampers....
Allergy and respiratory health effects of dampness and dampness-related agents in schools and homes
DEFF Research Database (Denmark)
Holst, G; Høst, A; Doekes, G
2016-01-01
was identified based on technical inspection and bedroom dampness on parents' self-report. Classroom and bedroom dust was analysed for seven microbial components. Skin-prick-testing determined atopic sensitisation. Lung function was expressed as z-scores for forced expiratory volume in one second (zFEV1...... ), forced vital capacity (zFVC) and the ratio zFEV1 /zFVC using GLI-2012-prediction-equations. The parents reported children's allergies, airway symptoms and doctor-diagnosed asthma. High classroom dampness, but not bedroom dampness, was negatively associated with zFEV1 (β-coef. -0.71; 95%CI -1.17 - -0...... (ETS) decreased zFEV1 (β-coef. -0.22; 95%CI -0.42- -0.02) and zFEV1 /zFVC-ratio (β-coef. -0.26; 95%CI -0.44 - -0.07) and increased upper airway symptoms (OR1.66; 95%CI 1.03-2.66). In conclusion, dampness in classrooms may have adverse respiratory health effects in pupils, but microbial agents...
NiTiCu/AlN/NiTiCu shape memory thin film heterostructures for vibration damping in MEMS
Energy Technology Data Exchange (ETDEWEB)
Kaur, Navjot; Kaur, Davinder, E-mail: dkaurfph@iitr.ernet.in
2014-03-25
Highlights: • Fabrication of NiTiCu/AlN/NiTiCu heterostructure using dc/rf magnetron sputtering. • Exhibits highest hardness (38 GPa) and elastic modulus (187 GPa). • Enhanced dissipation of mechanical energy (E{sub d} = 5.7 N J). • High damping capacity (0.052) and figure of merit (∼0.62). • Can be applied for vibration damping in MEMS. -- Abstract: Shape memory alloy (NiTiCu) thin films coupled with piezoelectric AlN layer produce an intelligent material for vibration damping. In the present study pure NiTiCu, NiTiCu/AlN and NiTiCu/AlN/NiTiCu heterostructures have been deposited on Si substrate using magnetron sputtering technique. By the use of the interfaces and shape memory effect provided by NiTiCu layers, the damping capacity can be increased along with increase in stiffness and mechanical hardness. The heterostructures were characterized in terms of structural, electrical, morphological and mechanical properties by X-ray diffraction (XRD), four probe resistivity method, atomic force microscopy, field emission scanning electron microscopy, and nanoindentation. The NiTiCu/AlN/NiTiCu heterostructure exhibit enhanced mechanical and damping properties as compared to NiTiCu/AlN and pure NiTiCu. This enhancement in hardness and damping of the heterostructure could be attributed to the shape memory effect of NiTiCu, intrinsic piezoelectricity of AlN and increased number of interfaces in heterostructure that help in dissipation of mechanical vibrations. The findings of this work provide additional impetus for the application of these heterostructures in emerging fields of nanotechnology and microelectro mechanical (MEMS) devices.
NiTiCu/AlN/NiTiCu shape memory thin film heterostructures for vibration damping in MEMS
International Nuclear Information System (INIS)
Kaur, Navjot; Kaur, Davinder
2014-01-01
Highlights: • Fabrication of NiTiCu/AlN/NiTiCu heterostructure using dc/rf magnetron sputtering. • Exhibits highest hardness (38 GPa) and elastic modulus (187 GPa). • Enhanced dissipation of mechanical energy (E d = 5.7 N J). • High damping capacity (0.052) and figure of merit (∼0.62). • Can be applied for vibration damping in MEMS. -- Abstract: Shape memory alloy (NiTiCu) thin films coupled with piezoelectric AlN layer produce an intelligent material for vibration damping. In the present study pure NiTiCu, NiTiCu/AlN and NiTiCu/AlN/NiTiCu heterostructures have been deposited on Si substrate using magnetron sputtering technique. By the use of the interfaces and shape memory effect provided by NiTiCu layers, the damping capacity can be increased along with increase in stiffness and mechanical hardness. The heterostructures were characterized in terms of structural, electrical, morphological and mechanical properties by X-ray diffraction (XRD), four probe resistivity method, atomic force microscopy, field emission scanning electron microscopy, and nanoindentation. The NiTiCu/AlN/NiTiCu heterostructure exhibit enhanced mechanical and damping properties as compared to NiTiCu/AlN and pure NiTiCu. This enhancement in hardness and damping of the heterostructure could be attributed to the shape memory effect of NiTiCu, intrinsic piezoelectricity of AlN and increased number of interfaces in heterostructure that help in dissipation of mechanical vibrations. The findings of this work provide additional impetus for the application of these heterostructures in emerging fields of nanotechnology and microelectro mechanical (MEMS) devices
Structural dynamic analysis with generalized damping models analysis
Adhikari , Sondipon
2013-01-01
Since Lord Rayleigh introduced the idea of viscous damping in his classic work ""The Theory of Sound"" in 1877, it has become standard practice to use this approach in dynamics, covering a wide range of applications from aerospace to civil engineering. However, in the majority of practical cases this approach is adopted more for mathematical convenience than for modeling the physics of vibration damping. Over the past decade, extensive research has been undertaken on more general ""non-viscous"" damping models and vibration of non-viscously damped systems. This book, along with a related book
Dynamic apeerture in damping rings with realistic wigglers
Energy Technology Data Exchange (ETDEWEB)
Cai, Yunhai; /SLAC
2005-05-04
The International Linear Collider based on superconducting RF cavities requires the damping rings to have extremely small equilibrium emittance, huge circumference, fast damping time, and large acceptance. To achieve all of these requirements is a very challenging task. In this paper, we will present a systematic approach to designing the damping rings using simple cells and non-interlaced sextupoles. The designs of the damping rings with various circumferences and shapes, including dogbone, are presented. To model realistic wigglers, we have developed a new hybrid symplectic integrator for faster and accurate evaluation of dynamic aperture of the lattices.
Amplitude dependent damping in single crystalline high purity molybdenum
International Nuclear Information System (INIS)
Zelada-Lambri, G.I; Lambri, O.A; Garcia, J.A; Lomer, J.N
2004-01-01
Amplitude dependent damping measurements were performed on high purity single crystalline molybdenum at several different constant temperatures between room temperature and 1273K. The employed samples were single crystals with the orientation, having a residual resistivity ratio of about 8000. Previously to the amplitude dependent damping tests, the samples were subjected to different thermomechanical histories. Amplitude dependent damping effects appear only during the first heating run in temperature where the samples have the thermomechanical state of the deformation process at room temperature. In the subsequent run-ups in temperature, i.e, after subsequent annealings, amplitude dependent damping effects were not detected (au)
Damping element for reducing the vibration of an airfoil
Campbell, Christian X; Marra, John J
2013-11-12
An airfoil (10) is provided with a tip (12) having an opening (14) to a center channel (24). A damping element (16) is inserted within the opening of the center channel, to reduce an induced vibration of the airfoil. The mass of the damping element, a spring constant of the damping element within the center channel, and/or a mounting location (58) of the damping element within the center channel may be adjustably varied, to shift a resonance frequency of the airfoil outside a natural operating frequency of the airfoil.
Small horizontal emittance in the TESLA damping ring
International Nuclear Information System (INIS)
Decking, W.
2001-01-01
The present TESLA damping ring is designed for a normalized horizontal emittance of 8x10 -6 m. γ-γ collisions at the TESLA linear collider will benefit from a further decrease of the horizontal emittance. This paper reviews the processes which limit the horizontal emittance in the damping ring. Preliminary estimates on the smallest horizontal emittance for the present TESLA damping ring design as well as an ultimate limit of the emittance reachable with the TESLA damping ring concept will be given
Mechanism of biological control of Rhizoctonia damping-off of ...
African Journals Online (AJOL)
MOHSEN
2014-01-29
Jan 29, 2014 ... Analysis of pectin contents from dried hypocotyls tissues showed highly methylated pectin with ..... methyl esters in pectic substances of the R. solani- ... affected by the pectin esterase and polygalacturonase released by the ...
MD 1407 - Landau Damping: Beam Transfer Functions and diffusion mechanisms
Tambasco, Claudia; Boccardi, Andrea; Buffat, Xavier; Gasior, Marek; Lefevre, Thibaut; Levens, Tom; Pojer, Mirko; Salvachua Ferrando, Belen Maria; Solfaroli Camillocci, Matteo; Pieloni, Tatiana; Crouch, Matthew Paul; CERN. Geneva. ATS Department
2017-01-01
In the 2012, 2015 and 2016 run several instabilities were developing at flat-top, during and at the end of the betatron squeeze where beam-beam interactions are present. The tune spread in the beams is therefore modified by the beam-beam long-range interactions and by other sources of spread. Studies of the stability area computed by evaluating the dispersion integral for different tune spreads couldn’t explain the observed instabilities during the squeeze and stable beams. The size of the stability area given by the computed dispersion integral depends on the transverse tune spread but its shape is defined by the particle distribution in the beams. Therefore any change of the particle distribution can lead to a deterioration of the Landau stability area. The Beam Transfer Functions (BTF) are direct measurements of the Stability Diagrams (SD). They are sensitive to particle distributions and contain information about the transverse tune spread in the beams. In this note are summarized the results of the BTF...
Thermal and mechanical damping of solar p-modes
International Nuclear Information System (INIS)
Goldreich, P.; Kumar, P.
1991-01-01
Nonadiabatic effects associated with the transfer of energy and with turbulent stresses add small imaginary parts, ω-i(1) and ω-i(2), to solar p-mode eigenfrequencies. Numerical calculations have shown that these quite different processes make comparable contributions to ω-i at frequencies well below the acoustic cutoff at ω-ac. Analytic expressions are derived which reveal the connection between ω-i(1) and ω-i(2). The estimates yield ω-i proportional to omega exp 8 for omega much less than omega-ac in good agreement with the numerical calculations. However, the observed line width is proportional to omega exp 4.2 at low frequencies. It is suspected that there is an unmodeled component of perturbed convective energy transport or of turbulent viscosity that makes an important contribution to ω-i at omega much less than ω-ac. 8 refs
ANALISIS SPASIAL KEJADIAN DEMAM BERDARAH DENGUE BERDASARKAN KEPADATAN PENDUDUK
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Agcrista Permata Kusuma
2016-01-01
Full Text Available Abstrak Puskesmas Kedungmundu merupakan wilayah endemis DBD dengan kasus yang tinggi. Diperlukan upaya dalam menentukan kebijakan strategi pengendalian vektor secara efektif dan efisien. Analisis spasial dalam SIG dapat digunakan untuk mengetahui pola penyebaran dan daerah potensi penularan DBD. Jenis penelitian ini adalah penelitian deskriptif analitik menggunakan pendekatan cross sectional. Teknik pengambilan sampel menggunakan sampel wilayah memperhatikan proporsi sampel dengan jumlah sampel 146 responden. Pengambilan titik koordinat menggunakan GPS. Analisis data menggunakan analisis univariat dan analisis spasial. Hasil perhitungan statistik spasial ANN diperoleh nilai Z-score = -11,054 terdapat pola spasial kasus DBD di wilayah kerja Puskesmas Kedungmundu. Nilai ANN = 0,52 < 1, artinya pola penyebaran kejadian DBD yang terjadi adalah berkerumun. Kesimpulan dalam penelitian ini sebaran kasus DBD memiliki keterkaitan secara spasial dengan kepadatan penduduk. Abstract Kedungmundu PHC is an endemich region with a high case. Be required to determine policy of vector control strategies effectively and efficiently. Spatial analsys in GIS can be used to determine the pattern of distribution and areas of DHF potential transmission. The type this research was analysis descriptive with cross sectional approach. The sampling technique used a sample area of attention to the proportion of the sample with 146 respondents of total sample. Capturing the coordinates used GPS. Data analisys used univariat and spatial analisys. Result of ANN obtained a Z-score= -11,054, there was a spatial pattern of dengue cases in Kedungmundu PHC. ANN value = 0,52 < 1, it meant that the pattern of DHF distribution was clustered. The conclution of this research was DHF distribution cases has spatial correlation with density population.
ANALISIS GEN HAEMAGGLUTININ PADA VIRUS CAMPAK LIAR
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Subangkit Subangkit
2015-05-01
Full Text Available AbstrakPenyakit Campak disebabkan oleh virus campak yang termasuk genus Morbilivirus dan Family Paramyxoviridae. Penyakit campak masih menjadi masalah kesehatan karena masih ditemukan Kejadian Luar Biasa (KLB di Indonesia. Salah satu penyebab terjadinya KLB tersebut diduga sebagaiakibat perbedaan antigenesitas antara strain vaksin yang digunakan dengan strain virus campak liar yang beredar di Indonesia. Penelitian ini bertujuan mendapatkan gambaran tentang karakteristik genetik gen Haemagglutinin virus campak liar yang ada di Indonesia. Spesimen yang digunakan sebanyak 27 isolat virus penyebab KLB dari 17 propinsi selama periode tahun 2003-2010. Isolat virus dilakukan pemeriksaan secara RT-PCR dan sekuensing dengan metode Sanger. Hasil sekuensing dianalisis dengan menggunakan perangkat lunak Bioedit 7.0 dan MEGA 4.0. Hasil penelitian didapatkan perbedaan 10 asam amino antara virus campak strain vaksin CAM-70 dan virus campak liar pada posisi D416N; K424T; V451M; N455T; V466I; I473T; F476L; Y481S atau Y481N; H495N; G505D. Kesimpulan penelitian ini adalah terdapat perbedaan karakteristik genetik antara virus campak liar di Indonesia berbeda dengan strain virus vaksin CAM-70.Kata kunci : Campak, Analisis Molekuler, Hemagglutinin, CD46AbstractMeasles is caused by virus belonging to the genus Morbilivirus and Family Paramyxoviridae. Measles is still a public health problem because outbreak of measles still found in Indonesia. Outbreak is suspected as a result of differences in antigenicity between vaccine strains used with wild-type measles virus strains circulating in Indonesia. This study aims to get genetic characteristics of wild-type measles virus haemagglutinin gene in Indonesia. The specimens were used 27 viral isolates from 17 provinces period 2003-2010. Viral isolates examined by RT-PCR and sequencing with Sanger method. Sequencing analysis were conducted using Bioedit 7.0 and MEGA 4.0 software. The results showed 10 amino acid differences
Analisis Kelayakan Finansial Usaha Budidaya Bambu
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Husnul Khotimah
2015-12-01
Full Text Available Budidaya bambu diperlukan untuk menambah populasi bambu yang cenderung berkurang yang disebabkan oleh beralihnya fungsi lahan yang digunakan untuk pemukiman atau diganti dengan komoditi tanaman lain yang dianggap lebih menguntungkan. Sementara itu kebutuhan bahan baku bambu terus meningkat sejalan dengan pertumbuhan penduduk dan perkembangan kemajuan ilmu pengetahuan. Budidaya bambu bermanfaat selain untuk menjaga ketersediaan suplai juga untuk meningkatkan kualitas bambu untuk memenuhi permintaan pasar. Tulisan ini mengkaji analisis finansial dari penanaman bambu. Kajian finansial dibutuhkan untuk menunjukkan bahwa upaya penanaman atau budidaya bambu ini layak atau tidak secara finansial untuk dilakukan. Data yang digunakan adalah data hasil penelitian di perusahaan perkebunan bambu PT XYZ di Lampung. Hasil penelitian menunjukkan bahwa nilai NPV (Rp 36.644.364,08 lebih besar dari nol, Net B/C (2,56 lebih besar dari satu, IRR (11 % lebih besar dari suku bunga 6 %, serta payback period pada tahun ke-9 umur proyek 15 tahun. Berdasarkan kriteria indikator kelayakan finansial dapat disimpulkan bahwa usaha budidaya bambu layak secara finansial untuk diusahakan. Katakunci: Hasil Hutan Bukan Kayu (HHBK, budidaya bambu, studi kelayakan, analisis finansial Financial analysis and feasibity study of bamboo cultivation Abstract Bamboo cultivation is necessary to increase the population of bamboo clumps. The bamboo clumps tend to decrease due to the shift of used lands for residential or replaced by other crop comodities, which are considered more profitable. On the other hand, the need of bamboo for raw materials remain increase in line with population growth and the development of science. The important of the bamboo cultivation are to maintain the availability of its supply and to improve the quality of bamboo, which meet the market demands. This paper examined financial analysis of bamboo cultivation. Financial study was necessary to show whether
Lee, Tae-Hoon; Han, Chulhee; Choi, Seung-Bok
2018-01-01
This work proposes a novel type of tunable magnetorheological (MR) damper operated based solely on the location of a permanent magnet incorporated into the piston. To create a larger damping force variation in comparison with the previous model, a different design configuration of the permanent-magnet-based MR (PMMR) damper is introduced to provide magnetic flux dispersion in two magnetic circuits by utilizing two materials with different magnetic reluctance. After discussing the design configuration and some advantages of the newly designed mechanism, the magnetic dispersion principle is analyzed through both the formulated analytical model of the magnetic circuit and the computer simulation based on the magnetic finite element method. Sequentially, the principal design parameters of the damper are determined and fabricated. Then, experiments are conducted to evaluate the variation in damping force depending on the location of the magnet. It is demonstrated that the new design and magnetic dispersion concept are valid showing higher damping force than the previous model. In addition, a curved structure of the two materials is further fabricated and tested to realize the linearity of the damping force variation.
Piping damping tests evaluating influence of types of support and excitation
International Nuclear Information System (INIS)
Arendts, J.G.; Ware, A.G.; Gorman, V.W.
1985-01-01
The United States Nuclear Regulatory Commission and the Electric Power Research Institute have jointly sponsored construction of two laboratory piping systems at the ANCO Engineers facility in California. EG and G Idaho used the second of these systems to obtain piping system damping data using different supports and methods of excitation. The 6-in. carbon steel piping system was approximately 50 ft in length with two 3-in. branch lines. It was supported at five locations and excited using a single electrohydraulic shaker. Both random and swept sine methods of excitations were used. A variable support attached near the shaker location allowed four different configurations to be tested: a rigid strut, a mechanical snubber, a hydraulic snubber, and a rigid strut with a gap. Data were recorded for the lowest nine significant modes. Damping for the first three modes ranged for 1 to 3% of critical damping and decreased as frequency increased. The random excitation produced a slightly higher average overall damping of the system
Excitation and damping of transversal oscillation in coronal loops by wake phenomena
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A abedini
2018-02-01
Full Text Available Transversal oscillation of coronal loops that are interpreted as signatures of magneto hydrodynamics (MHD waves are observed frequently in active region corona loops. The amplitude of this oscillation has been found to be strongly attenuated. The damping of transverse oscillation may be produced by the dissipation mechanism and the wake of the traveling disturbance. The damping of transversal loop oscillations with wake phenomena is not related to any dissipation mechanism. Also, these kinds of coronal loop oscillations are not related to the kink mode, although this mode can be occurred after the attenuation process by the energy of the wave packet deposited in the loop. In this paper the excitation and damping of transversal coronal loop oscillations with wake of traveling wave packet is discussed in detail, both theoretically and observationally. Here, the transversal coronal loop oscillations is modeled with a one dimensional simple line-tied. The dynamics of the loop and the coronal is governed by the Klein–Gordon differential equation. A localized disturbance that can be generated by nearby flare produces a perturbation that undergoes dispersion as it propagates toward the loop. As a consequence, the amplitudes of oscillates decay with time roughly t-1/2 at the external cutoff frequency. These observed data on 2016-Dec-4 by Atmospheric Imaging Assembly (AIA onboard Solar Dynamic Observatory (SDO observations data, consisting of 560 images with an interval of 24 seconds in the 171 A0 pass band is analyzed for evidence of excitation and damping of transverse oscillations of coronal loop that is situated near a flare. In this analyzed signatures of transverse oscillations that are damped rapidly were found, with periods in the range of P=18.5-23.85 minutes. Furthermore, oscillation of loop segments attenuate with time roughly as t-α that average values of α for 4 different loops change form 0.65-0.80. The magnitude values of α are in
Principles of TRIP Steel Optimization for Passive Damping Applications
Fraley, George Jay
Globally many historic structures of cultural significance which do not have systems to mitigate seismic damage are located in areas with heavy seismic activity. Efforts have been undertaken to develop strategies to retrofit such structures, however any intervention must be limited in size for aesthetic reasons. To contribute to this effort, ArcelorMittal aims to create steel-based solutions for passive energy dissipation through plastic deformation during cyclic loading. High-strength TRansformation-Induced Plasticity (TRIP) steels are proposed as an excellent candidate material for this application, due to the extreme combination of high strength and large ductility they are well-known to exhibit. To evaluate high-strength TRIP steels for passive damping applications, isothermal, fully-reversed, displacement-controlled Ultra-Low Cycle Fatigue (ULCF) experiments (Nf stainless steel 316, despite having a yield strength approximately four times larger. For a similar number of cycles to failure the high stability condition dissipated 2.4 times more energy than stainless steel 316 upon initial cycling. The stress-strain hysteresis curves and fatigue life data generated can be input into computational models of passive damping devices for initial concurrent material/device design iterations. Evidence of shear lips, large primary inclusions serving as fracture-initiation sites, and highly dimpled fracture surfaces confirmed for all failed specimens that ductile fracture mechanisms contribute to failure under ULCF conditions. For specimens failing in 10-11 cycles large protrusions aligned along the transverse direction were found, indicating that intergranular fracture may also be playing a role in ULCF failures for this alloy. To explore lower cost alternatives to fully-austenitic TRIP steels for passive-damping devices, austenite precipitation and its effect on uniaxial-tension mechanical properties in martensitic steels was investigated. Isothermal dilatometry
Analisis Korelasi Kanonik Hubungan Perilaku Pemimpin dan Motivasi Kerja Karyawan
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I Gusti Ayu Made Srinadi
2014-06-01
Full Text Available Kualitas pemimpin merupakan penentu keberhasilan organisasi yang dipimpin. Hubungan antara pemimpin dengan karyawannya merupakan hubungan saling ketergantungan yang umumnya tidak seimbang. Dalam proses interaksi yang terjadi antara pemimpin dan karyawan, berlangsung proses saling memengaruhi. Penelitian ini bertujuan untuk mencari hubungan perilaku pemimpin terhadap motivasi kerja karyawan dengan menggunakan analisis korelasi kanonik. Pengujian dengan menggunakan analisis korelasi kanonik menunjukkan bahwa perilaku pemimpin dengan motivasi karyawan memiliki keeratan hubungan dengan nilai korelasi kanonik sebesar 0,9058533. Faktor perilaku pemimpin yang paling tinggi berkorelasi dengan motivasi kerja karyawan di McDonald’s Kuta Beach adalah faktor kemampuan mengarahkan dan menghadapi karyawan dengan nilai korelasi yaitu sebesar 0,7619707.
Analisis Korelasi Kanonik Hubungan Perilaku Pemimpin dan Motivasi Kerja Karyawan
Directory of Open Access Journals (Sweden)
I Gusti Ayu Made Srinadi
2015-04-01
Full Text Available Kualitas pemimpin merupakan penentu keberhasilan organisasi yang dipimpin. Hubungan antara pemimpin dengan karyawannya merupakan hubungan saling ketergantungan yang umumnya tidak seimbang. Dalam proses interaksi yang terjadi antara pemimpin dan karyawan, berlangsung proses saling memengaruhi. Penelitian ini bertujuan untuk mencari hubungan perilaku pemimpin terhadap motivasi kerja karyawan dengan menggunakan analisis korelasi kanonik. Pengujian dengan menggunakan analisis korelasi kanonik menunjukkan bahwa perilaku pemimpin dengan motivasi karyawan memiliki keeratan hubungan dengan nilai korelasi kanonik sebesar 0,9058533. Faktor perilaku pemimpin yang paling tinggi berkorelasi dengan motivasi kerja karyawan di McDonald’s Kuta Beach adalah faktor kemampuan mengarahkan dan menghadapi karyawan dengan nilai korelasi yaitu sebesar 0,7619707.
Analisis Aliran Daya Berbasis Injeksi Arus dalam Bentuk Vektor
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Ahmad Wira Satriawan
2017-11-01
Full Text Available Tulisan ini memaparkan hasil penelitian yang telah dilakukan untuk membandingkan metode analisis aliran daya berbasis injeksi arus dalam bentuk vektor dengan format polar dan rektangular. Penelitian ini dilakukan untuk memperoleh metode analisa aliran daya dengan perhitungan yang lebih cepat dan akurat, serta iterasi yang lebih sedikit. Metode iterasi Newton Raphson diadopsi dalam penelitian ini dan bahasa pemrograman Python serta library komputasinya digunakan. Analisis terhadap karakteristik konvergensi dari kedua format dilakukan pada IEEE 14-bus Test System. Dari penelitian ini diperoleh hasil bahwa format rektangular lebih unggul dibandingkan format polar untuk kasus yang diteliti.
ENHANCEMENT OF DAMPING PERFORMANCE OF POLYMERS BY FUNCTIONAL SMALL MOLECULES
Institute of Scientific and Technical Information of China (English)
Chi-fei Wu; Saburo Akiyama
2002-01-01
The addition effects of organic small molecular substances N,N'-dicyclohexyl-benzothiazyl-2-sulfenamide (DZ) and 3,9-bis{ 1, 1-dimethyl-2[β-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionyloxy]ethyl}-2,4,8, 10-tetraoxaspiro[5,5]-undecane (AO-80) on the dynamic mechanical properties of chlorinated polyethylene (CPE), chlorinated polypropylene (CPP), acrylate rubber (ACM) and their blends were investigated. In the case of compatible systems such as CPE/DZ and ACM/AO-80, the height of the loss tangent (tanδ) peak of a matrix polymer (CPE or ACM) increases, and its peak position shifts to a higher temperature with the addition of DZ or AO-80. By contrast, for incompatible CPE/AO-80, a novel transition appeared above the glass transition temperature of CPE. This additional transition was assigned to dissociation of the intermolecular hydrogen bond between the α-hydrogen of CPE and the hydroxyl groups of AO-80 within the AO-80-rich domain. This will provide a new concept for developing damping material. However, the minimum value between two tanδ peaks is lower. It was found that the temperature dependence of tanδ could be improved by adding chlorinated paraffin (CP) or ACM to CPE/AO-80. In addition, another ternary system of ACM/CPP with more AO-80 was found to be a very good self-adhesive damping material because of the appearance of a novel transition due to an interfacial layer of ACM/CPP.
Bounce-harmonic Landau Damping of Plasma Waves
Anderegg, Francois
2015-11-01
We present measurement of plasma wave damping, spanning the temperature regimes of direct Landau damping, bounce-harmonic Landau damping, inter-species drag damping, and viscous damping. Direct Landau damping is dominant at high temperatures, but becomes negligible as v vph / 5 . The measurements are conducted in trapped pure ion plasmas contained in Penning-Malmberg trap, with wave-coherent LIF diagnostics of particle velocities. Our focus is on bounce harmonics damping, controlled by an applied ``squeeze'' potential, which generates harmonics in the wave potential and in the particle dynamics. A particle moving in z experiences a non-sinusoidal mode potential caused by the squeeze, producing high spatial harmonics with lower phase velocity. These harmonics are Landau damped even when the mode phase velocity vph is large compared to the thermal velocity v , since the nth harmonic is resonant with a particle bouncing at velocity vb =vph / n . Here we increase the bounce harmonics through applied squeeze potential; but some harmonics are always present in finite length systems. For our centered squeeze geometry, theory shows that only odd harmonics are generated, and predicts the Landau damping rate from vph / n . Experimentally, the squeeze potential increases the wave damping and reduces its frequency. The frequency shift occurs because the squeeze potential reduces the number of particle where the mode velocity is the largest, therefore reducing the mode frequency. We observe an increase in the damping proportional to Vs2,and a frequency reduction proportional to Vs , in quantitative agreement with theory. Wave-coherent laser induced fluorescence allows direct observation of bounce resonances on the particle distribution, here predominantly at vph / 3 . A clear increase of the bounce harmonics is visible on the particle distribution when the squeeze potential is applied. Supported by NSF Grant PHY-1414570, and DOE Grants DE-SC0002451 and DE-SC0008693.
Grover, D.; Seth, R. K.
2018-05-01
Analysis and numerical results are presented for the thermoelastic dissipation of a homogeneous isotropic, thermally conducting, Kelvin-Voigt type circular micro-plate based on Kirchhoff's Love plate theory utilizing generalized viscothermoelasticity theory of dual-phase-lagging model. The analytical expressions for thermoelastic damping of vibration and frequency shift are obtained for generalized dual-phase-lagging model and coupled viscothermoelastic plates. The scaled thermoelastic damping has been illustrated in case of circular plate and axisymmetric circular plate for fixed aspect ratio for clamped and simply supported boundary conditions. It is observed that the damping of vibrations significantly depend on time delay and mechanical relaxation times in addition to thermo-mechanical coupling in circular plate under resonance conditions and plate dimensions.
ANALISIS POTENSI RETRIBUSI PELAYANAN PASAR DI KABUPATEN KENDAL
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Herru Dwi Haryono
2017-06-01
Full Text Available Selama periode 2008-2012, realisasi retribusi pelayanan pasar ini mengalami tren naik turun. Sedangkan dari target yang ditentukan dalam komponen retribusi pelayanan pasar yakni retribusi pasar, retribusi sampah/kebersihan dan retribusi sewa kios rata-rata selalu terealisasi melebihi target. Penelitian ini bertujuan untuk mengetahui potensi retribusi pelayanan pasar di Kabupaten Kendal dan apakah target yang ditentukan sudah berdasarkan potensi yang ada. Data yang digunakan dalam penelitian ini adalah data sekunder. Data sekunder dalam penelitian ini berupa data yang bersumber dari BPS Kabupaten Kendal, DPPKAD Kabupaten Kendal, Disperindag Kabupaten Kendal dan UPTD Dinas Pasar Kabupaten Kendal. Metode analisis yang digunakan yakni analisis deskriptif yakni menghitung potensi retribusi pelayanan pasar di Kabupaten Kendal dan membandingkan potensi dengan target dan apakah target yang ditentukan sesuai berdasarkan potensi yang ada. Hasil penelitian menunjukkan bahwa (1 potensi retribusi pelayanan pasar di Kabupaten Kendal sebesar Rp.5.130.789.600 pertahun. (2 target retribusi pelayanan pasar di Kabupaten Kendal selalu berada dibawah potensi yang ada, jadi kesimpulannya bahwa mekanisme penentuan target tidak berdasarkan potensi yang ada. Berdasarkan hasil anasilis data tersebut, saran yang dapat disampaikan adalah agar pemerintah daerah ataupun pengelola pasar dapat memanfaatkan secara maksimal potensi yang ada agar realisasi penerimaan retribusi pelayanan pasar dapat ditingkatkan lagi dan hendaknya mengevaluasi mekanisme penetapan target berdasarkan potensi yang ada agar kinerja pemerintah maupun pengelola pasar dapat ditingkatkan lagi yang akan berdampak pada realisasi penerimaan retribusi pelayanan pasar. During the period 2008-2012, the actual levy of service this market has been trending up and down. While the targets specified in the component market services levy market fees, garbage fees / levies hygiene and the average
ANALISIS FAKTOR KEHADIRAN DOSEN DI UNIVERSITAS X
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Annisa Mulia Rani
2016-10-01
Full Text Available Aspek kualitas pekerjaan berkaitan langsung dengan waktu yang khusus digunakan dosen untuk mengembangkan kemampuan. Maka untuk merealisasikan kualitas dosen yang terbaik , pihak manajemen khusunya dekan membuat peraturan untuk kehadiran dosen adalah minimal 25 jam/minggu. Dengan peraturan ini diharapkan dosen dapat melaksanakan beban kerja dosen sebaik-baiknya. Peraturan ini tertulis dan tertuang pada SK Dekan No 20/2006 pada kampus X. Dengan Menggunakan Analisis faktor mencoba menemukan hubungan atar sejumlah variable-variabel yang awalnya saling independen satu dengan yang lain dimana variable penyebab kekurangan jam dosen datang/minggu adalah keluaraga, manajemen, hubungan social, fasilitas pengajaran, jarak/lokasi, kompensasi transport. Berdasarkan uji Bartley test dan Measure sample of adequate yang pertama maka dengan nilai sig 0.04 dan msa 0.540 . Dengan menggunakan metode principal component analysis maka pembentukan factor hanya ada 1 componen karena nilai eigen value yang mempunyai nilai diatas 1. Faktor pembentuk baru yaitu manajemen, kompensasi dan jarak menjadi satu component.
Analisis Gameplay Game Genre Virtual Pet
Directory of Open Access Journals (Sweden)
Abi Senoprabowo
2015-02-01
Full Text Available Game adalah struktur interaktif yang membuat pemain berjuang menuju sebuah tujuan. Game dapat memberikan emosi dan mood, menghubungkan dengan orang latihan, sarana latihan, serta dapat memberikan edukasi. Salah satu game yang berkembang saat ini adalah game bergenre Virtual pet. Game virtual pet merupakan game simulasi memelihara sesuatu. Virtual pet memiliki gameplay yang menarik dan menyenangkan yang membuat pemain seolah-olah benar-benar memiliki binatang peliharaan mereka sendiri. Virtual pet dianggap oleh sebagian besar penggunanya dapat memberikan kegembiraan serta rasa kasih sayang karena tingkat interaksinya yang baik. Banyak pengembang game pemula yang mengembangkan genre ini sebagai game yang mereka buat karena kemudahaan dan tingkat penggunanya yang banyak. Akan tetapi banyak dari pengembang game pemula tidak memperhatikan tingkat keberlanjutan game virtual pet yang mereka buat sehingga membuat pemain cepat bosan. Pada penelitian ini, analisis game bergenre virtual pet yang sudah sukses dibuat seperti Zombigotchi, Tamagotchi Unicorn, dan Bird Land, diharapkan dapat membantu para pengembang game pemula agar mengetahui cara merancang dan mengembangkan game virtual pet dengan baik. Kata Kunci: game, gameplay, virtual pet
ANALISIS MODEL KEPUASAN TERHADAP PEMBELIAN ULANG
Directory of Open Access Journals (Sweden)
Naili Farida
2014-09-01
Full Text Available Tujuan penelitian ini yaitu untuk menguji pengaruh brand equity, nilai pelanggan dan lifestyle yang dimediasi kepuasan konsumen terhadap pembelian ulang produk gadget di Kota Semarang. Responden dalam penelitian ini adalah seluruh konsumen yang telah melakukan pembelian produk gadget merek Samsung, sebanyak 120 orang. Teknik sampling yang digunakan yaitu purposive sampling. Teknik analisis yang digunakan yaitu Partial Least Square (PLS. Hasil penelitian menunjukkan bahwa terdapat pengaruh brand equity terhadap kepuasan, namun dalam konteks lifestyle dan nilai pelanggan tidak ada pengaruh terhadap kepuasan. Sedangkan kepuasan menunjukkan adanya pengaruh terhadap pembelian ulang. Diharapkan dari hasil penelitian ini mampu meningkatkan pembelian ulang melalui brand equity, lifestyle dan nilai pelanggan dalam konteks kepuasan. The objective of the research was to test the influence of brand equity, customer value and lifestyle which were mediated by consumer satisfaction toward re-purchasing of gadget products in Semarang. The respondents of the study were all consumers who have purchased Samsung gadget products. It was a purposive sampling study with 120 respondents. The data were analyzed by Partial Least Square (PLS. The result of the study showed that there was an influence of brand equity toward satisfaction, but in the lifestyle context and customer value did not give any influence toward satisfaction. Whereas; the satisfaction gave influence toward re-purchase. It is expected that this study can increase the repurchasethrough brand equity, lifestyle and customer values in the satisfaction context.
Seismic damping factors of small bore piping as influenced by insulation and support elements
International Nuclear Information System (INIS)
Severud, L.K.; Anderson, M.J.; Barta, D.A.
1985-01-01
Seismic damping tests of a prototypical Liquid Metal Fast Breeder Reactor (LMFBR) small bore piping system is described, and measured transient responses to pulse excitations are reported. The test specimen was representative of a typical LMFBR insulated small bore piping system, and it was supported from a rigid test frame by prototypic dead weight supports, mechanical snubbers, and pipe clamps. Various support configurations were tested to assess the response sensitivity to insulation and other nonlinear support characteristics. Damping factors increased significantly due to the insulation and use of mechanical snubbers. Factors much higher than the magnitudes currently allowed in design by the USNRC Regulatory Guide 1.61, were found. This verified the design values, and it also pointed out the possibility of undue conservatism and costly overdesign resulting from use of the present design values
Seismic damping factors of small bore piping as influenced by insulation and support elements
International Nuclear Information System (INIS)
Severud, L.K.; Barta, D.A.
1983-01-01
Seismic damping tests of a prototypical Liquid Metal Fast Breeder Reactor (LMFBR) small bore piping system is described, and measured transient responses to pulse excitations are reported. The test specimen was representative of a typical LMFBR insulated small bore piping system, and it was supported from a rigid test frame by prototypic dead weight supports, mechanical snubbers, and pipe clamps. Various support configurations were tested to assess the response sensitivity to insulation and other nonlinear support characteristics. Damping factors increased significantly due to the insulation and use of mechanical snubbers. Factors much higher than the magnitudes currently allowed in design, by the USNRC Regulatory Guide 1.61, were found. This verified the design values but also pointed out the possibility of undue conservatism and costly overdesign resulting from use of the present design values
Dynamic characteristics of a novel damped outrigger system
Tan, Ping; Fang, Chuangjie; Zhou, Fulin
2014-06-01
This paper presents exact analytical solutions for a novel damped outrigger system, in which viscous dampers are vertically installed between perimeter columns and the core of a high-rise building. An improved analytical model is developed by modeling the effect of the damped outrigger as a general rotational spring acting on a Bernoulli-Euler beam. The equivalent rotational spring stiffness incorporating the combined effects of dampers and axial stiffness of perimeter columns is derived. The dynamic stiffness method (DSM) is applied to formulate the governing equation of the damped outrigger system. The accuracy and efficiency are verified in comparison with those obtained from compatibility equations and boundary equations. Parametric analysis of three non-dimensional factors is conducted to evaluate the influences of various factors, such as the stiffness ratio of the core to the beam, position of the damped outrigger, and the installed damping coefficient. Results show that the modal damping ratio is significantly influenced by the stiffness ratio of the core to the column, and is more sensitive to damping than the position of the damped outrigger. The proposed analytical model in combination with DSM can be extended to the study of structures with more outriggers.
Semilinear damped wave equation in locally uniform spaces
Czech Academy of Sciences Publication Activity Database
Michálek, Martin; Pražák, D.; Slavík, J.
2017-01-01
Roč. 16, č. 5 (2017), s. 1673-1695 ISSN 1534-0392 EU Projects: European Commission(XE) 320078 - MATHEF Institutional support: RVO:67985840 Keywords : damped wave equations * nonlinear damping * unbounded domains Subject RIV: BA - General Mathematics OBOR OECD: Pure mathematics Impact factor: 0.801, year: 2016 http://www.aimsciences.org/journals/displayArticlesnew.jsp?paperID=14110
Dynamic stability of a lightly damped column trapped by a ...
African Journals Online (AJOL)
In this paper we initiate an analytical approach for determining the dynamic buckling load of a finite viscously damped column acted upon by a harmonically slowly varying explicitly time dependent load. The viscous damping is considered light and the column rests on an elastic foundation that produces a nonlinear ...
Damping and Frequency Shift of Large Amplitude Electron Plasma Waves
DEFF Research Database (Denmark)
Thomsen, Kenneth; Juul Rasmussen, Jens
1983-01-01
The initial evolution of large-amplitude one-dimensional electron waves is investigated by applying a numerical simulation. The initial wave damping is found to be strongly enhanced relative to the linear damping and it increases with increasing amplitude. The temporal evolution of the nonlinear...
Quantum theory of damped harmonic oscillator | Antia | Global ...
African Journals Online (AJOL)
The exact solutions of the Schrödinger equation for damped harmonic oscillator with pulsating mass and modified Caldirola-Kanai Hamiltonian are evaluated. We also investigated the case of under-damped for the two models constructed and the results obtained in both cases do not violate Heisenberg uncertainty principle ...
Simple model with damping of the mode-coupling instability
Energy Technology Data Exchange (ETDEWEB)
Pestrikov, D V [AN SSSR, Novosibirsk (Russian Federation). Inst. Yadernoj Fiziki
1996-08-01
In this paper we use a simple model to study the suppression of the transverse mode-coupling instability. Two possibilities are considered. One is due to the damping of particular synchrobetatron modes, and another - due to Landau damping, caused by the nonlinearity of betatron oscillations. (author)
Exponential decay for solutions to semilinear damped wave equation
Gerbi, Stéphane
2011-10-01
This paper is concerned with decay estimate of solutions to the semilinear wave equation with strong damping in a bounded domain. Intro- ducing an appropriate Lyapunov function, we prove that when the damping is linear, we can find initial data, for which the solution decays exponentially. This result improves an early one in [4].
Process Damping and Cutting Tool Geometry in Machining
Taylor, C. M.; Sims, N. D.; Turner, S.
2011-12-01
Regenerative vibration, or chatter, limits the performance of machining processes. Consequences of chatter include tool wear and poor machined surface finish. Process damping by tool-workpiece contact can reduce chatter effects and improve productivity. Process damping occurs when the flank (also known as the relief face) of the cutting tool makes contact with waves on the workpiece surface, created by chatter motion. Tool edge features can act to increase the damping effect. This paper examines how a tool's edge condition combines with the relief angle to affect process damping. An analytical model of cutting with chatter leads to a two-section curve describing how process damped vibration amplitude changes with surface speed for radiussed tools. The tool edge dominates the process damping effect at the lowest surface speeds, with the flank dominating at higher speeds. A similar curve is then proposed regarding tools with worn edges. Experimental data supports the notion of the two-section curve. A rule of thumb is proposed which could be useful to machine operators, regarding tool wear and process damping. The question is addressed, should a tool of a given geometry, used for a given application, be considered as sharp, radiussed or worn regarding process damping.
Equivalent viscous damping procedure for multi-material systems
International Nuclear Information System (INIS)
Ahmed, H.; Ma, D.
1979-01-01
The inclusion of accurate viscous damping effects in the seismic analysis of nuclear power plants is discussed. A procedure to evaluate and use equivalent viscous damping coefficients in conjunction with the substructure method of finite element analysis is outlined in detail
Comparing Sources of Damping of Cross-Wind Motion
DEFF Research Database (Denmark)
Tarp-Johansen, Niels Jacob; Mørch, Christian; Andersen, Lars
2009-01-01
practise plays a key role in this. The questions are: does more damping exist and is one of the sources of damping the main contributor allowing for site-independent guidelines. The aim of this paper is to address these issues. It is demonstrated that tower dampers are important in order to tackle...
PID motion control tuning rules in a damping injection framework
Tadele, T.S.; de Vries, Theodorus J.A.; Stramigioli, Stefano
2013-01-01
This paper presents a general design approach for a performance based tuning of a damping injection framework impedance controller by using insights from PID motion control tuning rules. The damping injection framework impedance controller is suitable for human friendly robots as it enhances safety
Dynamic response analysis of a 24-story damped steel structure
Feng, Demin; Miyama, Takafumi
2017-10-01
In Japanese and Chinese building codes, a two-stage design philosophy, damage limitation (small earthquake, Level 1) and life safety (extreme large earthquake, Level 2), is adopted. It is very interesting to compare the design method of a damped structure based on the two building codes. In the Chinese code, in order to be consistent with the conventional seismic design method, the damped structure is also designed at the small earthquake level. The effect of damper systems is considered by the additional damping ratio concept. The design force will be obtained from the damped design spectrum considering the reduction due to the additional damping ratio. The additional damping ratio by the damper system is usually calculated by a time history analysis method at the small earthquake level. The velocity dependent type dampers such as viscous dampers can function well even in the small earthquake level. But, if steel damper is used, which usually remains elastic in the small earthquake, there will be no additional damping ratio achieved. On the other hand, a time history analysis is used in Japan both for small earthquake and extreme large earthquake level. The characteristics of damper system and ductility of the structure can be modelled well. An existing 24-story steel frame is modified to demonstrate the design process of the damped structure based on the two building codes. Viscous wall type damper and low yield steel panel dampers are studied as the damper system.
Canonical quantization of the Bateman-Morse-Feshbach damped oscillator
International Nuclear Information System (INIS)
Rideau, G.; Anderson, R.L.; Hebda, P.W.
1991-01-01
The Bateman-Morse-Feshbach classical formulation of the damped oscillator is canonically quantized. The spectrum of the Hamiltonian is given. It is shown that the wavefunctions behave asymptotically as a superposition of damped oscillators when their initial values belong to an appropriately-selected dense subset of the Hilbert space. (orig.)
Exploring damping characteristics of composite tower of cable ...
Indian Academy of Sciences (India)
SHEHATA E ABDEL RAHEEM
the seismic design [1–7] by dividing the cable-stayed bridge into several ..... damping characteristics is represented by a simple model to study the effect of ...... lent modal damping of short-span bridges subjected to strong motion. J. Bridge ...
Study of Ion Acoustic Wave Damping through Green's Functions
DEFF Research Database (Denmark)
Hsuan, H.C.S.; Jensen, Vagn Orla
1973-01-01
Green's function analyses of ion acoustic waves in streaming plasmas show that, in general, the waves damp algebraically rather than exponentially with distance from exciter.......Green's function analyses of ion acoustic waves in streaming plasmas show that, in general, the waves damp algebraically rather than exponentially with distance from exciter....
Design guide for calculating fluid damping for circular cylindrical structures
International Nuclear Information System (INIS)
Chen, S.S.
1983-06-01
Fluid damping plays an important role for structures submerged in fluid, subjected to flow, or conveying fluid. This design guide presents a summary of calculational procedures and design data for fluid damping for circular cylinders vibrating in quiescent fluid, crossflow, and parallel flow
Process Damping and Cutting Tool Geometry in Machining
International Nuclear Information System (INIS)
Taylor, C M; Sims, N D; Turner, S
2011-01-01
Regenerative vibration, or chatter, limits the performance of machining processes. Consequences of chatter include tool wear and poor machined surface finish. Process damping by tool-workpiece contact can reduce chatter effects and improve productivity. Process damping occurs when the flank (also known as the relief face) of the cutting tool makes contact with waves on the workpiece surface, created by chatter motion. Tool edge features can act to increase the damping effect. This paper examines how a tool's edge condition combines with the relief angle to affect process damping. An analytical model of cutting with chatter leads to a two-section curve describing how process damped vibration amplitude changes with surface speed for radiussed tools. The tool edge dominates the process damping effect at the lowest surface speeds, with the flank dominating at higher speeds. A similar curve is then proposed regarding tools with worn edges. Experimental data supports the notion of the two-section curve. A rule of thumb is proposed which could be useful to machine operators, regarding tool wear and process damping. The question is addressed, should a tool of a given geometry, used for a given application, be considered as sharp, radiussed or worn regarding process damping.
Design of the SLC damping ring to linac transport lines
International Nuclear Information System (INIS)
Fieguth, T.H.; Murray, J.J.
1983-07-01
The first and second order optics for the damping ring to linac transport line are designed to preserve the damped transverse emittance while simultaneously compressing the bunch length of the beam to that length required for reinjection into the linac. This design, including provisions for future control of beam polarization, is described
Seismic response and damping tests of small bore LMFBR piping and supports
International Nuclear Information System (INIS)
Barta, D.A.; Anderson, M.J.; Severud, L.K.; Lindquist, M.R.
1984-01-01
Seismic testing and analysis of a prototypical Liquid Metal Fast Breeder Reactor (LMFBR) small bore piping system is described. Measured responses to simulated seismic excitations are compared with analytical predictions based on NRC Regulatory Guide 1.61 and measured system damping values. The test specimen was representative of a typical LMFBR insulated small bore piping system, and it was supported from a rigid test frame by prototypic dead weight supports, mechanical snubbers and pipe clamps
Wall-plug efficiency analysis of semi-active piezoelectric shunt damping systems
Czech Academy of Sciences Publication Activity Database
Václavík, Jan; Kodejška, M.; Mokrý, Pavel
2014-01-01
Roč. 20, September (2014), 1077546314548910 ISSN 1077-5463 R&D Projects: GA MŠk(CZ) LO1206; GA ČR GA13-10365S Institutional support: RVO:61389021 Keywords : Piezoelectric shunt damping * vibration isolation * negative capacitor * wall-plug efficiency * mechanical power measurement * power supply optimization Subject RIV: BI - Acoustics Impact factor: 4.355, year: 2013 http://jvc.sagepub.com/content/early/2014/09/17/1077546314548910
Wall-plug efficiency analysis of semi-active piezoelectric shunt damping systems
Czech Academy of Sciences Publication Activity Database
Václavík, Jan; Kodejška, M.; Mokrý, Pavel
2016-01-01
Roč. 22, č. 11 (2016), s. 2582-2590 ISSN 1077-5463 R&D Projects: GA MŠk(CZ) LO1206; GA ČR GA13-10365S Institutional support: RVO:61389021 Keywords : Piezoelectric shunt damping * vibration isolation * negative capacitor * wall-plug efficiency * mechanical power measurement * power supply optimization Subject RIV: BI - Acoustics Impact factor: 2.101, year: 2016 http://journals.sagepub.com/doi/abs/10.1177/1077546314548910
problem for the damped Boussinesq equation
Directory of Open Access Journals (Sweden)
Vladimir V. Varlamov
1997-01-01
Full Text Available For the damped Boussinesq equation utt−2butxx=−αuxxxx+uxx+β(u2xx,x∈(0,π,t>0;α,b=const>0,β=const∈R1, the second initial-boundary value problem is considered with small initial data. Its classical solution is constructed in the form of a series in small parameter present in the initial conditions and the uniqueness of solutions is proved. The long-time asymptotics is obtained in the explicit form and the question of the blow up of the solution in a certain case is examined. The possibility of passing to the limit b→+0 in the constructed solution is investigated.
Nonlinear piping damping and response predictions
International Nuclear Information System (INIS)
Severud, L.K.; Weiner, E.O.; Lindquist, M.R.; Anderson, M.J.; Wagner, S.E.
1986-10-01
The high level dynamic testing of four prototypic piping systems, used to provide benchmarks for analytical prediction comparisons, is overviewed. The size of pipe tested ranged from one-inch to six-inches in diameter and consisted of carbon steel or stainless steel material. Failure of the tested systems included progressive gross deformation or some combination of ratchetting-fatigue. Pretest failure predictions and post test comparisons using simplified elastic and elasto-plastic methods are presented. Detailed non-linear inelastic analyses are also shown, along with a typical ratchet-fatigue failure calculation. A simplified method for calculating modal equivalent viscous damping for snubbers and plastic hinges is also described. Conclusions are made regarding the applicability of the various analytical failure predictive methods and recommendations are made for future analytic and test efforts
Impedance effects in the CLIC damping rings
Koukovini-Platia, E; Mounet, N; Rumolo, G; Salvant, B
2011-01-01
Due to the unprecedented brilliance of the beams, the performance of the Compact Linear Collider (CLIC) damping rings (DR) is affected by collective effects. Single bunch instability thresholds based on a broad-band resonator model and the associated coherent tune shifts have been evaluated with the HEADTAIL code. Simulations performed for positive and negative values of chromaticity showed that higher order bunch modes can be potentially dangerous for the beam stability. This study also includes the effects of high frequency resistive wall impedance due to different coatings applied on the chambers of the wigglers for e-cloud mitigation and/or ultra-low vacuum pressure. The impact of the resistive wall wake fields on the transverse impedance budget is finally discussed.
Vibration-damping structure for reactor building
International Nuclear Information System (INIS)
Kuno, Toshio; Iba, Chikara; Tanaka, Hideki; Kageyama, Mitsuru
1998-01-01
In a damping structure of a reactor building, an inner concrete body and a reactor container are connected by way of a vibration absorbing member. As the vibration absorbing member, springs or dampers are used. The inner concrete body and the reactor container each having weight and inherent frequency different from each other are opposed displaceably by way of the vibration absorbing member thereby enabling to reduce seismic input and reduce shearing force at least at leg portions. Accordingly, seismic loads are reduced to increase the grounding rate of the base thereby enabling to satisfy an allowable value. Therefore, it is not necessary to strengthen the inner concrete body and the reactor container excessively, the amount of reinforcing rods can be reduced, and the amount of a portion of the base buried to the ground can be reduced thereby enabling to constitute the reactor building easily. (N.H.)
Gyroscopic stabilization and indefimite damped systems
DEFF Research Database (Denmark)
Pommer, Christian
a class of feasibel skew-Hermitian matrices A depending on the choise of M. The theory can be applied to dynamical systems of the form x''(t) + ( dD + g G) x'(t) + K x(t) = 0 where G is a skew symmetric gyrocopic matrix, D is a symmetric indefinite damping matrix and K > 0 is a positive definite stiffness......An important issue is how to modify a given unstable matrix in such a way that the resulting matrix is stable. We investigate in general under which condition a matrix M+A is stable,where M is an arbitrary matrix and A is skew-Hermitian. We show that if trace(M) > 0 it is always possible to find...
The electron damping ring for the SLAC Linear Collider
International Nuclear Information System (INIS)
Davies-White, W.; Hutton, A.; Harvey, A.
1987-10-01
A second damping ring to store and damp two electron bunches for the SLC project was constructed in 1985 and brought into operation early in 1986. Although generally similar to the damping ring (now used for positrons) constructed earlier, there are a number of design improvements and changes. The dipole magnetic field was raised to 2.1 T to improve damping. Sextupole fields were provided by separate permanent magnets, rather than being incorporated in the dipoles. The vacuum chambers, including the beam position monitors, were re-designed for lower longitudinal impedance. A new kicker was developed by Fermilab to handle the two electron bunches. Improvements were made to the dc septum magnet design. Several of the features are described in detail elsewhere. Where possible, the improvements were incorporated in an upgrade of the earlier damping ring
Techniques for the design of highly damped structures
International Nuclear Information System (INIS)
Nelson, F.C.
1975-01-01
This paper discusses several techniques for the design of highly damped structures, techniques which have proven successful for large scale, low frequency steel and concrete structures which are typical of nuclear power reactors and their components. The ability to augment structural damping can be useful in increasing the seismic withstandability of structures. Seismic excitation is broadband in its frequency content and will excite many strutural resonances. Broadband damping will limit these resonant responses and thereby reduce the seismic load on structures and their components. This paper discusses three techniques: the design of structural joints and interfaces to promote damping; the use of layers of viscoelastic material; and the employment of damping links. The emphasis is on explaining the ways in which these techniques work and in describing the ways in which they have been used. (Auth.)
Impact of Damping Uncertainty on SEA Model Response Variance
Schiller, Noah; Cabell, Randolph; Grosveld, Ferdinand
2010-01-01
Statistical Energy Analysis (SEA) is commonly used to predict high-frequency vibroacoustic levels. This statistical approach provides the mean response over an ensemble of random subsystems that share the same gross system properties such as density, size, and damping. Recently, techniques have been developed to predict the ensemble variance as well as the mean response. However these techniques do not account for uncertainties in the system properties. In the present paper uncertainty in the damping loss factor is propagated through SEA to obtain more realistic prediction bounds that account for both ensemble and damping variance. The analysis is performed on a floor-equipped cylindrical test article that resembles an aircraft fuselage. Realistic bounds on the damping loss factor are determined from measurements acquired on the sidewall of the test article. The analysis demonstrates that uncertainties in damping have the potential to significantly impact the mean and variance of the predicted response.
Research on the Multilayer Free Damping Structure Design
Directory of Open Access Journals (Sweden)
Jie Meng
2018-01-01
Full Text Available The aim of this paper is to put forward a design model for multilayer free damping structures. It sets up a mathematical model and deduces the formula for its structural loss factor η and analyzes the change rules of η along with the change rate of the elastic modulus ratio q1, the change rate of the loss factors of damping materials q2, and the change rate of the layer thickness ratio q3 under the condition with the layer thickness ratio h2=1,3,5,10 by software MATLAB. Based on three specific damping structures, the mathematical model is verified through ABAQUS. With the given structural loss factor (η≥2 and the layer number (n=3,4,5,6, 34 kinds of multilayer free damping structures are then presented. The study is meant to provide a more flexible and more diverse design solution for multilayer free damping structures.
Robinson's radiation damping sum rule: Reaffirmation and extension
International Nuclear Information System (INIS)
Mane, S.R.
2011-01-01
Robinson's radiation damping sum rule is one of the classic theorems of accelerator physics. Recently Orlov has claimed to find serious flaws in Robinson's proof of his sum rule. In view of the importance of the subject, I have independently examined the derivation of the Robinson radiation damping sum rule. Orlov's criticisms are without merit: I work through Robinson's derivation and demonstrate that Orlov's criticisms violate well-established mathematical theorems and are hence not valid. I also show that Robinson's derivation, and his damping sum rule, is valid in a larger domain than that treated by Robinson himself: Robinson derived his sum rule under the approximation of a small damping rate, but I show that Robinson's sum rule applies to arbitrary damping rates. I also display more concise derivations of the sum rule using matrix differential equations. I also show that Robinson's sum rule is valid in the vicinity of a parametric resonance.
Damping of Inter-Area Low Frequency Oscillation Using an Adaptive Wide-Area Damping Controller
DEFF Research Database (Denmark)
Yao, Wei; Jiang, L.; Fang, Jiakun
2013-01-01
This paper presents an adaptive wide-area damping controller (WADC) based on generalized predictive control (GPC) and model identification for damping the inter-area low frequency oscillations in large-scale inter-connected power system. A recursive least-squares algorithm (RLSA) with a varying...... forgetting factor is applied to identify online the reduced-order linearlized model which contains dominant inter-area low frequency oscillations. Based on this linearlized model, the generalized predictive control scheme considering control output constraints is employed to obtain the optimal control signal...... conditions and different disturbances, but also has better robustness against to the time delay existing in the remote signals. The comparison studies with the conventional lead-lag WADC are also provided....
Calculations of emittance and damping time effects in the SLC damping rings
International Nuclear Information System (INIS)
Limberg, T.; Moshammer, H.; Raubenheimer, T.; Spencer, J.; Siemann, R.
1992-03-01
In a recent NDR machine experiment the transverse emittance was studied as a function of store time and tune. To explain the observed transverse emittance damping time constants, the magnetic measurement data of the longitudinal field of the bending magnets had to be taken into account. The variation of the transverse emittances with tune due to misalignments and the associated anomalous dispersion is studied as well as the effect of synchrobetatron coupling due to dispersion in the RF cavities
Magneto-induced large deformation and high-damping performance of a magnetorheological plastomer
International Nuclear Information System (INIS)
Liu, Taixiang; Gong, Xinglong; Xu, Yangguang; Pang, Haoming; Xuan, Shouhu
2014-01-01
A magnetorheological plastomer (MRP) is a new kind of soft magneto-sensitive polymeric composite. This work reports on the large magneto-deforming effect and high magneto-damping performance of MRPs under a quasi-statical shearing condition. We demonstrate that an MRP possesses a magnetically sensitive malleability, and its magneto-mechanical behavior can be analytically described by the magneto-enhanced Bingham fluid-like model. The magneto-induced axial stress, which drives the deformation of the MRP with 70 wt % carbonyl iron powder, can be tuned in a large range from nearly 0.0 kPa to 55.4 kPa by an external 662.6 kA m −1 magnetic field. The damping performance of an MRP has a significant correlation with the magnetic strength, shear rate, carbonyl iron content and shear strain amplitude. For an MRP with 60 wt % carbonyl iron powder, the relative magneto-enhanced damping effect can reach as high as 716.2% under a quasi-statically shearing condition. Furthermore, the related physical mechanism is proposed, and we reveal that the magneto-induced, particle-assembled microstructure directs the magneto-mechanical behavior of the MRP. (paper)
Morphology and damping behavior of polyurethane/PMMA simultaneous interpenetrating networks
Directory of Open Access Journals (Sweden)
Wang S.H.
2001-01-01
Full Text Available A series of polyurethane/PMMA simultaneous interpenetrating networks (SINs with various hard segment contents (X in the polyurethane phase (X = 15.5 to 36.5% in polyurethane and wide range of polyurethane (PU to polyacrylate (PA ratio (PU/PA = 20:80 to 80:20 were prepared, and the damping and mechanical properties of these materials were studied. The damping of polyurethane soft phase was increased and shifted to lower temperature with increased content of PA vitreous phase. The mechanical properties were improved with increasing PA contents. The results show that PA and the polyurethane hard segment interaction play a special role in chain interpenetration density and its magnitude is revealed by the decreased dispersed domain size observed by scanning electron microscopy (SEM and increased loss area as measured by dynamic mechanical thermal analysis (DMTA. When the weight ratio of PU/PA was 40:60, the resulting SIN materials possessed better damping properties, independent of X concentration.
ANALISIS KONTRIBUSI PAJAK HOTEL TERHADAP PENDAPATAN ASLI DAERAH KABUPATEN NUNUKAN
-, MULIATI
2014-01-01
2014 Analisis Kontribusi Pajak Hotel terhadap Pendapatan Asli Daerah Kabupaten Nunukan Analysis of The Contributions Tax on Hotel Againts Regional Renenue Nunukan District Muliati Haerial M. Christian Mangiwa Penelitian ini bertujuan untuk mengetahui seberapa besar kontribusi pajak hotel terhadap pendapatan asli daerah, mengetahui sistem pengawasan, dan potensi yang ada untuk meningkatkan pajak hotel, mengetahui sistem dan prosedur...
Analisis Sektor/Sub Sektor Unggulan di Kabupaten Bungo
Directory of Open Access Journals (Sweden)
Gafur Gafur
2016-03-01
Full Text Available Abstract. This study aimed to analyze the leading sectors in Bungo. The method used is Location Quotient (LQ, Dynamic Location Quotient (DLQ, specialization index, Growth Ratio Model (MRP. Based on analysis of LQ and DLQ, there are only two basis sectors at present and in the future, namely the construction sector and trade, hotels and restaurants. Based on the analysis of Specialization Index, in Bungo Regency has a concentration of the economy in the agricultural sector and the manufacturing sector. Based on MRP analysis also showed that prominent sector growth at the level of Bungo and Jambi Province, namely electricity, gas and water supply; the building sector; and trade, hotels and restaurants. Keywords : Location Quotient (LQ, Dinamic Location Quotient (DLQ, Specialization Index, Growth Ratio Model Abstrak. Penelitian ini bertujuan untuk menganalisis sektor unggulan di Kabupaten Bungo. Metode yang digunakan adalah analisis Location Quotient (LQ, Dinamic Location Quotient (DLQ, indeks spesialisasi, Model Rasio Pertumbuhan (MRP. Berdasarkan analisis LQ dan DLQ, hanya ada 2 sektor yang menjadi sektor basis pada saat ini dan pada masa yang akan datang yaitu sektor bangunan dan sektor perdagangan, hotel dan restoran. Berdasarkan analisis Indeks Spesialisasi, di Kabupaten Bungo telah terjadi konsentrasi ekonomi pada sektor pertanian dan sektor industri pengolahan. Berdasarkan analisis MRP juga dapat diketahui bahwa sektor yang menonjol pertumbuhannya pada tingkat Kabupaten Bungo dan Provinsi Jambi yaitu sektor listrik, gas dan air bersih; sektor bangunan; serta sektor perdagangan, hotel dan restoran. Kata Kunci : Location Quotient (LQ, Dinamic Location Quotient (DLQ, indeks spesialisasi, Model Rasio Pertumbuhan
Uncertainty in microscale gas damping: Implications on dynamics of capacitive MEMS switches
International Nuclear Information System (INIS)
Alexeenko, Alina; Chigullapalli, Sruti; Zeng Juan; Guo Xiaohui; Kovacs, Andrew; Peroulis, Dimitrios
2011-01-01
Effects of uncertainties in gas damping models, geometry and mechanical properties on the dynamics of micro-electro-mechanical systems (MEMS) capacitive switch are studied. A sample of typical capacitive switches has been fabricated and characterized at Purdue University. High-fidelity simulations of gas damping on planar microbeams are developed and verified under relevant conditions. This and other gas damping models are then applied to study the dynamics of a single closing event for switches with experimentally measured properties. It has been demonstrated that although all damping models considered predict similar damping quality factor and agree well for predictions of closing time, the models differ by a factor of two and more in predicting the impact velocity and acceleration at contact. Implications of parameter uncertainties on the key reliability-related parameters such as the pull-in voltage, closing time and impact velocity are discussed. A notable effect of uncertainty is that the nominal switch, i.e. the switch with the average properties, does not actuate at the mean actuation voltage. Additionally, the device-to-device variability leads to significant differences in dynamics. For example, the mean impact velocity for switches actuated under the 90%-actuation voltage (about 150 V), i.e. the voltage required to actuate 90% of the sample, is about 129 cm/s and increases to 173 cm/s for the 99%-actuation voltage (of about 173 V). Response surfaces of impact velocity and closing time to five input variables were constructed using the Smolyak sparse grid algorithm. The sensitivity analysis showed that impact velocity is most sensitive to the damping coefficient whereas the closing time is most affected by the geometric parameters such as gap and beam thickness. - Highlights: → We examine stochastic non-linear response of a microsystem switch subject to multiple input uncertainties. → Sample devices have been fabricated and device
Phase compensated gas turbine governor for damping oscillatory modes
Energy Technology Data Exchange (ETDEWEB)
Yee, S.K. [Siemens Transmission and Distribution Limited, Manchester (United Kingdom); Milanovic, J.V. [School of Electrical and Electronic Engineering, University of Manchester, PO Box 88, Manchester M60 1 QD (United Kingdom); Hughes, F.M. [Manchester (United Kingdom)
2009-08-15
With market deregulation, there is constant pressure to utilise existing assets in more effective ways in order to achieve high levels of performance and as governor technologies mature the ability of governors to achieve much more than the standard power-frequency regulation function increases. Thus, this paper has focused on a more active use of governor control for a gas turbine to provide improved system stabilisation and performance via the inclusion of phase compensation in the governor control loop. Due to the decoupled nature of the mechanical power and excitation control loops, performance improvement via governor control does not interfere with generator voltage regulation, which is a drawback of conventional generator damping provision via a power system stabiliser (PSS). In addition, the mechanical power control loop is also less affected by the operating condition of the power system and is hence more robust. It is shown that inclusion of appropriate phase compensation in the governor control loop can improve dynamic and transient stability, either alone or in conjunction with a PSS in the exciter control loop, without adversely interfering with voltage control or changing steady state power-frequency regulation. (author)
Youssef, Jamal Ben; Brosseau, Christian
2006-12-01
The microwave damping mechanisms in magnetic inhomogeneous systems have displayed a richness of phenomenology that has attracted widespread interest over the years. Motivated by recent experiments, we report an extensive experimental study of the Gilbert damping parameter of multicomponent metal oxides micro- and nanophases. We label the former by M samples, and the latter by N samples. The main thrust of this examination is the magnetization dynamics in systems composed of mixtures of magnetic (γ-Fe2O3) and nonmagnetic (ZnO and epoxy resin) materials fabricated via powder processing. Detailed ferromagnetic resonance (FMR) measurements on N and M samples are described so to determine changes in the microwave absorption over the 6-18GHz frequency range as a function of composition and static magnetic field. The FMR linewidth and the field dependent resonance were measured for the M and N samples, at a given volume fraction of the magnetic phase. The asymmetry in the form and change in the linewidth for the M samples are caused by the orientation distribution of the local anisotropy fields, whereas the results for the N samples suggest that the linewidth is very sensitive to details of the spatial magnetic inhomogeneities. For N samples, the peak-to-peak linewidth increases continuously with the volume content of magnetic material. The influence of the volume fraction of the magnetic phase on the static internal field was also investigated. Furthermore, important insights are gleaned through analysis of the interrelationship between effective permeability and Gilbert damping constant. Different mechanisms have been considered to explain the FMR linewidth: the intrinsic Gilbert damping, the broadening induced by the magnetic inhomogeneities, and the extrinsic magnetic relaxation. We observed that the effective Gilbert damping constant of the series of N samples are found to be substantially smaller in comparison to M samples. This effect is attributed to the surface
ANALISIS KINERJA DENGAN MENGGUNAKAN PENDEKATAN RASIO CAMEL
Directory of Open Access Journals (Sweden)
Sri Murdiati
2015-06-01
Full Text Available Tujuan penelitian ini adalah untuk menganalisis tingkat kesehatan bank dilihat dari kategori CAMEL. Metode penelitian yang digunakan adalah studi kasus di PD BPR BKK Banjarharjo.Dalam menguji hipotesis digunakan alat analisis CAMEL. Hasil penelitian ini yaitu modal pada 2008 sampai 2010 termasuk dalam kriteria sehat. ROA meningkat 2008 sampai 2010 dengan kriteria sehat bagi biaya operasional yang dikeluarkan oleh pendapatan operasional yang seimbang. Rasio Kas tahun 2008 sampai 2010 termasuk dalam kriteria sehat berarti bank memiliki kemampuan untuk mengelola asset yang digunakan untuk membayar kewajiban. LDR mengalami tren yang signifikan selama tahun 2008 sampai 2010 sehingga dana yang diterima bank untuk meningkatkan baik tabungan, deposito berjangka, modal inti, yang berarti kemampuan bank untuk meningkatkan penyaluran kredit, IRR menunjukan nilai positif dalam menghadapi resiko pasar.Pengembangan tingkat kesehatan pada tahun 2008 sampai 2010 untuk komponen Capital, Assets, Laba dan Likuiditas meningkat. The goal of this research is to analyze the healtiness of banks seen from CAMEL category. The research applied a case study in PD BPR BKK Banjarharjo. The hypotheses tested using CAMEL analysis tools. The result of the study is that the modal used 2008 until 2010 is consideredin a healthy criteria. The increasing ROA in 2008 until 2010 is considered healthy criteria for operational expenses incurred by the operating income. Such condition meant that the banks are able to manage the assets which are used to pay the obligations. The significant increasing of LDR over the years 2008 until 2010 makes the received funds by the bank to increase the savings deposits, time deposits and the core capital. As the recunts, the banks are able to increase credit disstribution. More over, the IRR showed a positive values in the face of market risks and the development of healthy levels in 2008 until 2010 for the components of Capital, Assets, Earnings and
Perceptual studies of violin body damping and vibrato.
Fritz, Claudia; Woodhouse, Jim; Cheng, Felicia P-H; Cross, Ian; Blackwell, Alan F; Moore, Brian C J
2010-01-01
This work explored how the perception of violin notes is influenced by the magnitude of the applied vibrato and by the level of damping of the violin resonance modes. Damping influences the "peakiness" of the frequency response, and vibrato interacts with this peakiness by producing fluctuations in spectral content as well as in frequency and amplitude. Initially, it was shown that thresholds for detecting a change in vibrato amplitude were independent of body damping, and thresholds for detecting a change in body damping were independent of vibrato amplitude. A study of perceptual similarity using triadic comparison showed that vibrato amplitude and damping were largely perceived as independent dimensions. A series of listening tests was conducted employing synthesized, recorded, or live performance to probe perceptual responses in terms of "liveliness" and preference. The results do not support the conclusion that liveliness results from the combination of the use of vibrato and a "peaky" violin response. Judgments based on listening to single notes showed inconsistent patterns for liveliness, while preferences were highest for damping that was slightly less than for a reference (real) violin. In contrast, judgments by players based on many notes showed preference for damping close to the reference value.
Damping Identification of Bridges Under Nonstationary Ambient Vibration
Directory of Open Access Journals (Sweden)
Sunjoong Kim
2017-12-01
Full Text Available This research focuses on identifying the damping ratio of bridges using nonstationary ambient vibration data. The damping ratios of bridges in service have generally been identified using operational modal analysis (OMA based on a stationary white noise assumption for input signals. However, most bridges are generally subjected to nonstationary excitations while in service, and this violation of the basic assumption can lead to uncertainties in damping identification. To deal with nonstationarity, an amplitude-modulating function was calculated from measured responses to eliminate global trends caused by nonstationary input. A natural excitation technique (NExT-eigensystem realization algorithm (ERA was applied to estimate the damping ratio for a stationarized process. To improve the accuracy of OMA-based damping estimates, a comparative analysis was performed between an extracted stationary process and nonstationary data to assess the effect of eliminating nonstationarity. The mean value and standard deviation of the damping ratio for the first vertical mode decreased after signal stationarization. Keywords: Damping, Operational modal analysis, Traffic-induced vibration, Nonstationary, Signal stationarization, Amplitude-modulating, Bridge, Cable-stayed, Suspension
Directory of Open Access Journals (Sweden)
Lagerev I.A.
2016-03-01
Full Text Available The article was the analysis of dynamic processes in the cylindrical hinges with large gaps in the cargo boom crane-manipulating installations of mobile machines in operation. Consider the design of damping device for articulated joints, which creates a braking force of elastic resistance to the displacement of the hinge pin within the large gap. The mechanism of action of the damping devices was considered. Analysis of the effectiveness of damping device for re-ducing the dynamic stress state in the elements of cargo boom metal structures depending on the gap size and the stiff-ness of the damping device was performed. Damping device with an elastic shock absorbing elements substantially reduces the additional impact load at the time of selection of the gap in the joint, slow the growth of clearance in the pivot joint, limit the size of the gap specified value, which must not be exceeded during the entire service life of swivel independently from the intensity of his load.
Experimental validation of solid rocket motor damping models
Riso, Cristina; Fransen, Sebastiaan; Mastroddi, Franco; Coppotelli, Giuliano; Trequattrini, Francesco; De Vivo, Alessio
2017-12-01
In design and certification of spacecraft, payload/launcher coupled load analyses are performed to simulate the satellite dynamic environment. To obtain accurate predictions, the system damping properties must be properly taken into account in the finite element model used for coupled load analysis. This is typically done using a structural damping characterization in the frequency domain, which is not applicable in the time domain. Therefore, the structural damping matrix of the system must be converted into an equivalent viscous damping matrix when a transient coupled load analysis is performed. This paper focuses on the validation of equivalent viscous damping methods for dynamically condensed finite element models via correlation with experimental data for a realistic structure representative of a slender launch vehicle with solid rocket motors. A second scope of the paper is to investigate how to conveniently choose a single combination of Young's modulus and structural damping coefficient—complex Young's modulus—to approximate the viscoelastic behavior of a solid propellant material in the frequency band of interest for coupled load analysis. A scaled-down test article inspired to the Z9-ignition Vega launcher configuration is designed, manufactured, and experimentally tested to obtain data for validation of the equivalent viscous damping methods. The Z9-like component of the test article is filled with a viscoelastic material representative of the Z9 solid propellant that is also preliminarily tested to investigate the dependency of the complex Young's modulus on the excitation frequency and provide data for the test article finite element model. Experimental results from seismic and shock tests performed on the test configuration are correlated with numerical results from frequency and time domain analyses carried out on its dynamically condensed finite element model to assess the applicability of different equivalent viscous damping methods to describe
Public health and economic impact of dampness and mold
Energy Technology Data Exchange (ETDEWEB)
Mudarri, David; Fisk, William J.
2007-06-01
The public health risk and economic impact of dampness and mold exposures was assessed using current asthma as a health endpoint. Individual risk of current asthma from exposure to dampness and mold in homes from Fisk et al. (2007), and asthma risks calculated from additional studies that reported the prevalence of dampness and mold in homes were used to estimate the proportion of U.S. current asthma cases that are attributable to dampness and mold exposure at 21% (95% confidence internal 12-29%). An examination of the literature covering dampness and mold in schools, offices, and institutional buildings, which is summarized in the appendix, suggests that risks from exposure in these buildings are similar to risks from exposures in homes. Of the 21.8 million people reported to have asthma in the U.S., approximately 4.6 (2.7-6.3) million cases are estimated to be attributable to dampness and mold exposure in the home. Estimates of the national cost of asthma from two prior studies were updated to 2004 and used to estimate the economic impact of dampness and mold exposures. By applying the attributable fraction to the updated national annual cost of asthma, the national annual cost of asthma that is attributable to dampness and mold exposure in the home is estimated to be $3.5 billion ($2.1-4.8 billion). Analysis indicates that exposure to dampness and mold in buildings poses significant public health and economic risks in the U.S. These findings are compatible with public policies and programs that help control moisture and mold in buildings.
Application of small panel damping measurements to larger walls
Hastings, Mardi C.; Godfrey, Richard; Babcock, G. Madison
1996-05-01
Damping properties of a viscoelastic material were determined using a standard resonant beam technique. The damping material was then applied to 1 by 2 foot gypsum panels in a constrained layer construction. Damping loss factors in panels with and without the constrained layer were determined based on reverberation times after excitation at third-octave band center frequencies. The constrained damping layer had been designed to increase damping by an order of magnitude above that of a single gypsum panel at 2000 Hz; however, relative to a gypsum panel of the same overall thickness as the panel with the constrained layer, loss factors increased only by a factor of three to five. Next modal damping loss factors in 9 by 14 foot gypsum single and double walls were calculated from the experimentally determined quality factor for each modal resonance. Results showed that below 2500 Hz, modes in 1 by 2 foot gypsum panels had nearly the same damping loss factors as modes in a 9 by 14 foot gypsum wall of the same thickness; however, loss factors for the wall were an order of magnitude lower than those of the 1 by 2 foot panels at frequencies above 2500 Hz, the coincidence frequency for 5/8-inch thick gypsum plates. Thus it was inconclusive whether or not damping loss factors measured using small panels could be used to estimate the effect of a constrained damping layer on transmission loss through a 9 by 14 foot wall unless boundary conditions and modal frequencies were the same for each size.
Experimental validation of solid rocket motor damping models
Riso, Cristina; Fransen, Sebastiaan; Mastroddi, Franco; Coppotelli, Giuliano; Trequattrini, Francesco; De Vivo, Alessio
2018-06-01
In design and certification of spacecraft, payload/launcher coupled load analyses are performed to simulate the satellite dynamic environment. To obtain accurate predictions, the system damping properties must be properly taken into account in the finite element model used for coupled load analysis. This is typically done using a structural damping characterization in the frequency domain, which is not applicable in the time domain. Therefore, the structural damping matrix of the system must be converted into an equivalent viscous damping matrix when a transient coupled load analysis is performed. This paper focuses on the validation of equivalent viscous damping methods for dynamically condensed finite element models via correlation with experimental data for a realistic structure representative of a slender launch vehicle with solid rocket motors. A second scope of the paper is to investigate how to conveniently choose a single combination of Young's modulus and structural damping coefficient—complex Young's modulus—to approximate the viscoelastic behavior of a solid propellant material in the frequency band of interest for coupled load analysis. A scaled-down test article inspired to the Z9-ignition Vega launcher configuration is designed, manufactured, and experimentally tested to obtain data for validation of the equivalent viscous damping methods. The Z9-like component of the test article is filled with a viscoelastic material representative of the Z9 solid propellant that is also preliminarily tested to investigate the dependency of the complex Young's modulus on the excitation frequency and provide data for the test article finite element model. Experimental results from seismic and shock tests performed on the test configuration are correlated with numerical results from frequency and time domain analyses carried out on its dynamically condensed finite element model to assess the applicability of different equivalent viscous damping methods to describe
International Nuclear Information System (INIS)
Yamaguchi, Hiroshi; Zhang, Xin-Rong; Niu, Xiao-Dong
2010-01-01
The damping characteristics and flow behaviors of ER fluids inside a piston–cylinder viscous damper subjected to external electric fields are studied based on experiment, theoretical analysis and numerical simulation. The viscous damper is a closed system with an inner piston and an outer cylinder, which is designed and constructed in our laboratory. In the experiment, the test ER fluid is enclosed in the gap of a piston–cylinder system. To examine the damping characteristics of the test ER fluid, a piston sine vibration experiment is performed with accompanying theoretical analyses. In addition, in order to investigate the ER flow behaviors inside the damper, a numerical simulation is carried out. The present study discloses the damping characteristics and the fluid mechanism of the ER fluid in the piston–cylinder damper with an applied external electric field
International Nuclear Information System (INIS)
Fasoli, A.F.; Testa, D.; Jaun, A.; Sharapov, S.; Gormezano, C.
2001-01-01
The linear stability properties of global modes that can be driven by resonant energetic particles or by the bulk plasma are studied using an external excitation method based on the JET saddle coil antennas. Low toroidal mode number, stable plasma modes are driven by the saddle coils and detected by magnetic probes to measure their structure, frequency and damping rate, both in the Alfven Eigenmode (AE) frequency range and in the low frequency Magneto-Hydro-Dynamic (MHD) range. For AEs, the dominant damping mechanisms are identified for different plasma conditions of relevance for reactors. Spectra and damping rates of low frequency MHD modes that are localized at the foot of the internal transport barrier and can affect the plasma performance in advanced tokamak scenarios have been directly measured for the first time. This gives the possibility of monitoring in real time the approach to the instability boundary. (author)
DEFF Research Database (Denmark)
Kliem, Mathias; Høgsberg, Jan Becker; Dannemann, Martin
2016-01-01
This paper deals with the characterization of the fibre-direction dependent damping capability of glass fibre reinforced plastics (GFRP) to be used in electrical power transmission pylons. A fibre-direction dependent damping analysis of unidirectional (UD) GFRP samples was carried out using...... a Dynamic Mechanical Analysis (DMA) for five different fibre orientations (0˚ | 30˚ | 45˚ | 60˚ and 90˚) and two different matrix systems (epoxy and a vinyl ester resin). Based on the dynamic characteristics the damping performance of the various composite materials was studied at three temperatures (-10˚C......, 0˚C and 10˚C) and three vibration frequencies (1 Hz, 10 Hz and 30 Hz). It was observed that the loss factor of Glass Fibre Reinforced Vinyl-Ester (GF-VE) was in general slightly higher compared to the Glass Fibre Reinforced Epoxy (GF-EP). The loss factor increased slightly with temperature, while...
Arsenyev, Sergey A.; Temkin, Richard J.; Shchegolkov, Dmitry Yu.; Simakov, Evgenya I.; Boulware, Chase H.; Grimm, Terry L.; Rogacki, Adam R.
2016-08-01
We present a study of higher order mode (HOM) damping in the first multicell superconducting radio-frequency (SRF) cavity with a photonic band gap (PBG) coupler cell. Achieving higher average beam currents is particularly desirable for future light sources and particle colliders based on SRF energy-recovery linacs (ERLs). Beam current in ERLs is limited by the beam breakup instability, caused by parasitic HOMs interacting with the beam in accelerating cavities. A PBG cell incorporated in an accelerating cavity can reduce the negative effect of HOMs by providing a frequency selective damping mechanism, thus allowing significantly higher beam currents. The five-cell cavity with a PBG cell was designed and optimized for HOM damping. Monopole and dipole HOMs were simulated. The SRF cavity was fabricated and tuned. External quality factors for some HOMs were measured in a cold test. The measurements agreed well with the simulations.
Directory of Open Access Journals (Sweden)
Sergey A. Arsenyev
2016-08-01
Full Text Available We present a study of higher order mode (HOM damping in the first multicell superconducting radio-frequency (SRF cavity with a photonic band gap (PBG coupler cell. Achieving higher average beam currents is particularly desirable for future light sources and particle colliders based on SRF energy-recovery linacs (ERLs. Beam current in ERLs is limited by the beam breakup instability, caused by parasitic HOMs interacting with the beam in accelerating cavities. A PBG cell incorporated in an accelerating cavity can reduce the negative effect of HOMs by providing a frequency selective damping mechanism, thus allowing significantly higher beam currents. The five-cell cavity with a PBG cell was designed and optimized for HOM damping. Monopole and dipole HOMs were simulated. The SRF cavity was fabricated and tuned. External quality factors for some HOMs were measured in a cold test. The measurements agreed well with the simulations.
A numerically efficient damping model for acoustic resonances in microfluidic cavities
Energy Technology Data Exchange (ETDEWEB)
Hahn, P., E-mail: hahnp@ethz.ch; Dual, J. [Institute of Mechanical Systems (IMES), Department of Mechanical and Process Engineering, ETH Zurich, Tannenstrasse 3, CH-8092 Zurich (Switzerland)
2015-06-15
Bulk acoustic wave devices are typically operated in a resonant state to achieve enhanced acoustic amplitudes and high acoustofluidic forces for the manipulation of microparticles. Among other loss mechanisms related to the structural parts of acoustofluidic devices, damping in the fluidic cavity is a crucial factor that limits the attainable acoustic amplitudes. In the analytical part of this study, we quantify all relevant loss mechanisms related to the fluid inside acoustofluidic micro-devices. Subsequently, a numerical analysis of the time-harmonic visco-acoustic and thermo-visco-acoustic equations is carried out to verify the analytical results for 2D and 3D examples. The damping results are fitted into the framework of classical linear acoustics to set up a numerically efficient device model. For this purpose, all damping effects are combined into an acoustofluidic loss factor. Since some components of the acoustofluidic loss factor depend on the acoustic mode shape in the fluid cavity, we propose a two-step simulation procedure. In the first step, the loss factors are deduced from the simulated mode shape. Subsequently, a second simulation is invoked, taking all losses into account. Owing to its computational efficiency, the presented numerical device model is of great relevance for the simulation of acoustofluidic particle manipulation by means of acoustic radiation forces or acoustic streaming. For the first time, accurate 3D simulations of realistic micro-devices for the quantitative prediction of pressure amplitudes and the related acoustofluidic forces become feasible.
Spider-silk-like shape memory polymer fiber for vibration damping
International Nuclear Information System (INIS)
Yang, Qianxi; Li, Guoqiang
2014-01-01
In this study, the static and dynamic properties of shape memory polyurethane (SMPU) fiber are reported and compared to those of spider dragline silk. Although the polymeric fiber has a lower strength compared to spider dragline silks (0.2–0.3 GPa versus 1.1 GPa), it possesses much higher toughness (276–289 MJ m −3 versus 160 MJ m −3 ), due to its excellent extensibility. The dynamic mechanical tests reveal that SMPU fiber has a high damping capacity (tan δ = 0.10–0.35) which is comparable to or even higher than that of spider silks (tan δ = 0.15). In addition, we found that, different programming methods change the shape memory and damping properties of the fiber in different ways and cold-drawing programming is more advocated in structural applications. These results suggest that the SMPU fiber has similar vibration damping and mechanical properties as spider silk, and may find applications in lightweight engineering structures. (paper)
Directory of Open Access Journals (Sweden)
Jia-li Gao
2014-01-01
Full Text Available Flight feather shaft of long-eared owl is characterized by a three-parameter model for linear viscoelastic solids to reveal its damping ability. Uniaxial tensile tests of the long-eared owl, pigeon, and golden eagle flight feather shaft specimens were carried out based on Instron 3345 single column material testing system, respectively, and viscoelastic response of their stress and strain was described by the standard linear solid model. Parameter fitting result obtained from the tensile tests shows that there is no significant difference in instantaneous elastic modulus for the three birds’ feather shafts, but the owl shaft has the highest viscosity, implying more obvious viscoelastic performance. Dynamic mechanical property was characterized based on the tensile testing results. Loss factor (tanδ of the owl flight feather shaft was calculated to be 1.609 ± 0.238, far greater than those of the pigeon (0.896 ± 0.082 and golden eagle (1.087 ± 0.074. It is concluded that the long-eared owl flight feather has more outstanding damping ability compared to the pigeon and golden eagle flight feather shaft. Consequently, the long-eared owl flight feathers can dissipate the vibration energy more effectively during the flying process based on the principle of damping mechanism, for the purpose of vibration attenuation and structure radiated noise reduction.
Travelling Solitons in the Damped Driven Nonlinear Schroedinger Equation
Barashenkov, I V
2003-01-01
The well-known effect of the linear damping on the moving nonlinear Schrodinger soliton (even when there is energy supply via the spatially homogeneous driving) is to quench its momentum to zero. Surprisingly, the zero momentum does not necessarily mean zero velocity. We show that two or more parametrically driven damped solitons can form a complex travelling with zero momentum at a nonzero constant speed. All travelling complexes we have found so far, turned out to be unstable. Thus, the parametric driving is capable of sustaining the uniform motion of damped solitons, but some additional agent is required to make this motion stable.
Effective damping for SSR analysis of parallel turbine-generators
International Nuclear Information System (INIS)
Agrawal, B.L.; Farmer, R.G.
1988-01-01
Damping is a dominant parameter in studies to determine SSR problem severity and countermeasure requirements. To reach valid conclusions for multi-unit plants, it is essential that the net effective damping of unequally loaded units be known. For the Palo Verde Nuclear Generating Station, extensive testing and analysis have been performed to verify and develop an accurate means of determining the effective damping of unequally loaded units in parallel. This has led to a unique and simple algorithm which correlates well with two other analytic techniques
On small vibrations of a damped Stieltjes string
Directory of Open Access Journals (Sweden)
Olga Boyko
2015-01-01
Full Text Available Inverse problem of recovering masses, coefficients of damping and lengths of the intervals between the masses using two spectra of boundary value problems and the total length of the Stieltjes string (an elastic thread bearing point masses is considered. For the case of point-wise damping at the first counting from the right end mass the problem of recovering the masses, the damping coefficient and the lengths of the subintervals by one spectrum and the total length of the string is solved.
Electronic Contributions to the Phonon Damping in Metals
Energy Technology Data Exchange (ETDEWEB)
Johnson, Rune
1968-07-15
An imaginary part of the dielectric matrix is derived based on a first order perturbation expansion of the valence electron states in a local potential model of the crystal. The results are used to estimate the electronic contributions to the phonon damping in aluminum and lead. The corrections which have been obtained are of the same order of magnitude at small phonon momenta as the damping earlier calculated for the free electrons. However, the discrepancies between the theoretical and experimental results still remain. The major contribution to damping seems to originate in anharmonic effects, even at 80 deg K.
Travelling solitons in the damped driven nonlinear Schroedinger equation
International Nuclear Information System (INIS)
Barashenkov, I.V.; Zemlyanaya, E.V.
2003-01-01
The well known effect of the linear damping on the moving nonlinear Schroedinger soliton (even when there is energy supply via the spatially homogeneous driving) is to quench its momentum to zero. Surprisingly, the zero momentum does not necessarily mean zero velocity. We show that two or more parametrically driven damped solitons can form a complex travelling with zero momentum at a nonzero constant speed. All travelling complexes we have found so far, turned out to be unstable. Thus, the parametric driving is capable of sustaining the uniform motion of damped solitons, but some additional agent is required to make this motion stable
DEFF Research Database (Denmark)
Knüppel, Thyge; Nielsen, Jørgen Nygård; Jensen, Kim Høj
2011-01-01
For a wind power plant (WPP) the upper limit for active power output is bounded by the instantaneous wind conditions and therefore a WPP must curtail its power output when system services with active power are delivered. Here, a power oscillation damping controller (POD) for WPPs is presented...... that utilizes the stored kinetic energy in the wind turbine (WT) mechanical system as energy storage from which damping power can be exchanged. This eliminates the need for curtailed active power production. Results are presented using modal analysis and induced torque coefficients (ITC) to depict the torques...... induced on the synchronous generators from the POD. These are supplemented with nonlinear time domain simulations with and without an auxiliary POD for the WPP. The work is based on a nonlinear, dynamic model of the 3.6 MW Siemens Wind Power wind turbine....
Parsons, David; Smith, Andrew; Knight, Brent; Hunt, Ron; LaVerde, Bruce; Craigmyle, Ben
2012-01-01
Particle dampers provide a mechanism for diverting energy away from resonant structural vibrations. This experimental study provides data from trials to determine how effective use of these dampers might be for equipment mounted to a curved orthogrid vehicle panel. Trends for damping are examined for variations in damper fill level, component mass, and excitation energy. A significant response reduction at the component level would suggest that comparatively small, thoughtfully placed, particle dampers might be advantageously used in vehicle design. The results of this test will be compared with baseline acoustic response tests and other follow-on testing involving a range of isolation and damping methods. Instrumentation consisting of accelerometers, microphones, and still photography data will be collected to correlate with the analytical results.
Dynamics of vibration isolation system with rubber-cord-pneumatic spring with damping throttle
Burian, Yu A.; Silkov, M. V.
2017-06-01
The study refers to the important area of applied mechanics; it is the theory of vibration isolation of vibroactive facilities. The design and the issues of mathematical modeling of pneumatic spring perspective design made on the basis of rubber-cord shell with additional volume connected with its primary volume by means of throttle passageway are considered in the text. Damping at the overflow of air through the hole limits the amplitude of oscillation at resonance. But in contrast to conventional systems with viscous damping it does not increase transmission ratio at high frequencies. The mathematical model of suspension allowing selecting options to reduce the power transmission ratio on the foundation, especially in the high frequency range is obtained
Knight, Brent; Parsons, David; Smith, Andrew; Hunt, Ron; LaVerde, Bruce; Towner, Robert; Craigmyle, Ben
2013-01-01
Particle dampers provide a mechanism for diverting energy away from resonant structural vibrations. This experimental study provides data from a series of acoustically excited tests to determine the effectiveness of these dampers for equipment mounted to a curved orthogrid panel for a launch vehicle application. Vibration attenuation trends are examined for variations in particle damper fill level, component mass, and excitation energy. A significant response reduction at the component level was achieved, suggesting that comparatively small, strategically placed, particle damper devices might be advantageously used in launch vehicle design. These test results were compared to baseline acoustic response tests without particle damping devices, over a range of isolation and damping parameters. Instrumentation consisting of accelerometers, microphones, and still photography data will be collected to correlate with the analytical results.
Heat and damp transport in cavity bricks. Waerme- und Feuchtetransport in Hochlochziegeln
Energy Technology Data Exchange (ETDEWEB)
Elsner, M
1987-11-19
The aim of this work is a systematic measurement of the structural effect of cavity bricks on the thermal insulation and thermal storage values depending on the material values of the bricks and the mortar. The arrangement and orientation of the hollow spaces and their dimensions should be varied. Brick shapes with socalled handle slots, which give more convenient handling, and with mortar pockets instead of mortar gaps, should be taken into account in the investigation. Special attention should be paid to the heat transport mechanism in the hollow spaces, where thermal conduction, thermal radiation and convection heat transport are superimposed on one another. The second main aim of the work is the calculation of the coupled heat and damp transport in hollow bricks. The heat and damp transport is described by a coupled system of differential equations, where the decisive transport coefficients should be shown as a function of the variables determining the transport processes. (orig./MM).
Nonlinear Damping Identification in Nonlinear Dynamic System Based on Stochastic Inverse Approach
Directory of Open Access Journals (Sweden)
S. L. Han
2012-01-01
Full Text Available The nonlinear model is crucial to prepare, supervise, and analyze mechanical system. In this paper, a new nonparametric and output-only identification procedure for nonlinear damping is studied. By introducing the concept of the stochastic state space, we formulate a stochastic inverse problem for a nonlinear damping. The solution of the stochastic inverse problem is designed as probabilistic expression via the hierarchical Bayesian formulation by considering various uncertainties such as the information insufficiency in parameter of interests or errors in measurement. The probability space is estimated using Markov chain Monte Carlo (MCMC. The applicability of the proposed method is demonstrated through numerical experiment and particular application to a realistic problem related to ship roll motion.
Effective mass and damping of submerged structures
International Nuclear Information System (INIS)
Dong, R.G.
1979-01-01
A number of structures important for safety in nuclear power plants are submerged in water. These include spent fuel storage racks, main pressure relief valve lines, and internal structures in the reactor vessel. Dynamic analyses of such structures must include the force and damping effects of water. A wide variety of modeling assumptions are being used in design analyses, and currently there are no uniform positions by which to judge the adequacy of the assumptions . A study was caried out to establish a technical basis for evaluating the assymptions and to recommend suitable methods to describe the effects of the water. The results of the study were based on information published in the literature or conveyed by industrial firms. A survey of 32 firms and 49 technical references was carried out. Heavy emphasis was placed on validating the results with available experimental data. The information collected apply generally to idealized structures such as single isolated members, arrays of members and coaxial cylinders. The results of the study are categorized with respect to such idealized structures, and the applicability to actual reactor structures was discussed through observations and recommendations. (orig.)
Effective mass and damping of submerged structures
International Nuclear Information System (INIS)
Dong, R.G.
1978-01-01
Various structures important for safety in nuclear power plants must remain functioning in the event of an earthquake or other dynamic phenomenon. Some of these important structures, such as spent-fuel storage racks, main pressure-relief valve lines, and internal structures in the reactor vessel, are submerged in water. Dynamic analysis must include the force and damping effects of water. This report provides a technical basis for evaluating the wide variety of modeling assumptions currently used in design analysis. Current design analysis techniques and information in the literature form the basis of our conclusions and recommendations. We surveyed 32 industrial firms and reviewed 49 technical references. We compare various theories with published experimental results wherever possible. Our findings generally pertain to idealized structures, such as single isolated members, arrays of members, and coaxial cylinders. We relate these findings to the actual reactor structures through observations and recommendations. Whenever possible we recommend a definite way to evaluate the effect of hydrodynamic forces on these structures
Coherent Instabilities of ILC Damping Ring
Energy Technology Data Exchange (ETDEWEB)
Heifets, S.; Stupakov, G.; Bane, K.; /SLAC
2006-09-27
The paper presents the first attempt to estimates the ILC damping ring impedance and compare thresholds of the classical instabilities for several designs initially proposed for the DR. The work was carried out in the spring of 2006. Since then the choice of the DR is narrowed. Nevertheless, the analysis described may be useful for the next iterations of the beam stability. Overall, the conventional instabilities will have little impact on the ring performance provided the careful design of the ring minimizes the impedance below acceptable level indicated above. The only exception is the transverse CB instability. The longitudinal CB is less demanding. However, even the transverse CB instability would have threshold current above nominal provided the aperture in the wigglers is increased from 8 mm to 16 mm. The microwave instability needs more studies. Nevertheless, we should remember that the ILC DR is different from existing high-current machines at least in two respects: absence of the beam-beam tune spread stabilizing beams in colliders, and unusual strict requirements for low emittance. That may cause new problems such as bunch emittance dilution due to high-frequency wakes (BPMs, grooves), etc. Even if such a possibility exists, it probably universal for all machines and ought be addressed in the design of vacuum components rather than have effect on the choice of the machine design.
Seismic Analysis of a Viscoelastic Damping Isolator
Directory of Open Access Journals (Sweden)
Bo-Wun Huang
2015-01-01
Full Text Available Seismic prevention issues are discussed much more seriously around the world after Fukushima earthquake, Japan, April 2011, especially for those countries which are near the earthquake zone. Approximately 1.8×1012 kilograms of explosive energy will be released from a magnitude 9 earthquake. It destroys most of the unprotected infrastructure within several tens of miles in diameter from the epicenter. People can feel the earthquake even if living hundreds of miles away. This study is a seismic simulation analysis for an innovated and improved design of viscoelastic damping isolator, which can be more effectively applied to earthquake prevention and damage reduction of high-rise buildings, roads, bridges, power generation facilities, and so forth, from earthquake disaster. Solidworks graphic software is used to draw the 3D geometric model of the viscoelastic isolator. The dynamic behavior of the viscoelastic isolator through shock impact of specific earthquake loading, recorded by a seismometer, is obtained via ANSYS finite element package. The amplitude of the isolator is quickly reduced by the viscoelastic material in the device and is shown in a time response diagram. The result of this analysis can be a crucial reference when improving the design of a seismic isolator.
Damping of forward neutrons in pp collisions
International Nuclear Information System (INIS)
Kopeliovich, B. Z.; Potashnikova, I. K.; Schmidt, Ivan; Soffer, J.
2008-01-01
We calculate absorptive corrections to single pion exchange in the production of leading neutrons in pp collisions. Contrary to the usual procedure of convolving the survival probability with the cross section, we apply corrections to the spin amplitudes. The nonflip amplitude turns out to be much more suppressed by absorption than the spin-flip one. We identify the projectile proton Fock state responsible for the absorptive corrections as a color octet-octet 5-quarks configuration. Calculations within two very different models, color-dipole light-cone description, and in hadronic representation, lead to rather similar absorptive corrections. We found a much stronger damping of leading neutrons than in some of previous estimates. Correspondingly, the cross section is considerably smaller than was measured at ISR. However, comparison with recent measurements by the ZEUS collaboration of neutron production in deep-inelastic scattering provides a strong motivation for challenging the normalization of the ISR data. This conjecture is also supported by preliminary data from the NA49 experiment for neutron production in pp collisions at SPS.
The DAMPE experiment: 2 year in orbit
Gargano, Fabio; DAMPE Collaboration
2017-12-01
The DArk Matter Particle Explorer (DAMPE) is a space mission within the strategic framework of the Chinese Academy of Sciences, resulting from a collaboration of Chinese, Italian, and Swiss institutions, and is a new addition to the growing number of particle detectors in space. It was successfully launched in December 2015 and has commenced nominal science operations since shortly after launch. Lending technologies from its predecessors such as AMS and Fermi-LAT, it features a powerful segmented electromagnetic calorimeter which thanks to its 31 radiation lengths enables the study of charged cosmic rays in the energy domain of up to 100 TeV and gamma rays of up to 10 TeV. The calorimeter is complemented with a silicon-tungsten tracker converter which yields a comparable angular resolution as current space-borne pair-conversion gamma-ray detectors. In addition, the detector features a top anti-coincidence shield made of segmented silicon plastic scintillators and a boron-doped plastic scintillator on the bottom of the instrument to detect delayed neutrons arising from cosmic ray protons showering in the calorimeter. An overview of the mission and a summary of the latest results in the domain of charged cosmic rays, gamma rays and heavy ions will be presented.
Dampness and Moisture Problems in Norwegian Homes
Directory of Open Access Journals (Sweden)
Rune Becher
2017-10-01
Full Text Available The occurrence of dampness and mold in the indoor environment is associated with respiratory-related disease outcomes. Thus, it is pertinent to know the magnitude of such indoor environment problems to be able to estimate the potential health impact in the population. In the present study, the moisture damage in 10,112 Norwegian dwellings was recorded based on building inspection reports. The levels of moisture damage were graded based on a condition class (CC, where CC0 is immaculate and CC1 acceptable (actions not required, while CC2 and CC3 indicate increased levels of damage that requires action. Of the 10,112 dwellings investigated, 3125 had verified moisture or mold damage. This amounts to 31% of the surveyed dwellings. Of these, 27% had CC2 as the worst grade, whereas 4% had CC3 as the worst grade level. The room types and building structures most prone to moisture damage were (in rank order crawl spaces, basements, un-insulated attics, cooling rooms, and bathrooms. The high proportion of homes with moisture damage indicate a possible risk for respiratory diseases in a relatively large number of individuals, even if only the more extensive moisture damages and those located in rooms where occupants spend the majority of their time would have a significant influence on adverse health effects.
Symmetries of the quantum damped harmonic oscillator
International Nuclear Information System (INIS)
Guerrero, J; López-Ruiz, F F; Aldaya, V; Cossío, F
2012-01-01
For the non-conservative Caldirola–Kanai system, describing a quantum damped harmonic oscillator, a couple of constant-of-motion operators generating the Heisenberg–Weyl algebra can be found. The inclusion of the standard time evolution generator (which is not a symmetry) as a symmetry in this algebra, in a unitary manner, requires a non-trivial extension of this basic algebra and hence of the physical system itself. Surprisingly, this extension leads directly to the so-called Bateman dual system, which now includes a new particle acting as an energy reservoir. In addition, the Caldirola–Kanai dissipative system can be retrieved by imposing constraints. The algebra of symmetries of the dual system is presented, as well as a quantization that implies, in particular, a first-order Schrödinger equation. As opposed to other approaches, where it is claimed that the spectrum of the Bateman Hamiltonian is complex and discrete, we obtain that it is real and continuous, with infinite degeneracy in all regimes. (paper)
The effect of inertia, viscous damping, temperature and normal ...
Indian Academy of Sciences (India)
Nitish Sinha
2018-04-16
Apr 16, 2018 ... physical parameters such as inertia, viscous damping, temperature and normal stress on the chaotic ... However, the present study has shown the appearance of chaos for the specific .... Although chaos is a general man-.
Multi-damping earthquake design spectra-compatible motion histories
International Nuclear Information System (INIS)
Choi, Dong-Ho; Lee, Sang-Hoon
2003-01-01
Two iterative methods of developing time histories compatible with multi-damping spectra are presented. The common method of forcing agreement among design and calculated spectral values at several frequencies and multiple damping values may give poor, even meaningless results. The two simple iterative techniques presented here use acceleration impulse functions for 'correcting' the time histories. In the first method the correction is calculated separately for each frequency and damping value and the maximum corresponding coefficient is used to correct the time history for the iteration. In the second method the solution is further improved by introducing a scale factor at each iteration. The effectiveness of the proposed techniques is illustrated by a comparison of a set of six multi-damping design spectra with spectral responses of a time history
R and D status of the ATF damping ring
International Nuclear Information System (INIS)
Urakawa, Junji
1994-01-01
The KEK accelerator test facility (ATF) is under construction. This paper gives the status of the design studies, the various R and D works and the construction for the damping ring of the ATF. (author)
Requirements for longitudinal HOM damping in superconducting recirculating linacs
International Nuclear Information System (INIS)
Bisognano, J.J.; Fripp, M.L.
1989-01-01
Transverse beam breakup provides the primary current limitation in the operation of superconducting recirculating linacs and requires the significant damping of transverse-deflecting higher order modes. The need to damp the coexisting longitudinal HOMs in these nominally isochronous machines, however, is not as clear. Isochronicity implies that energy variations induced by excitation of longitudinal modes do not translate directly into position and current modulations. Such modulations, if present, could enhance the initial excitation, effectively closing a potentially unstable feedback loop. Design optimization of cavity structures may suggest that no longitudinal damping be provided. On the other hand, easing of the isochronicity requirement may provide desired flexibility in lattice design. In this note, limits are placed on the requirements for longitudinal HOM damping and on the tolerances for isochronicity which are driven by possible longitudinal multipass phenomena. 2 refs., 1 fig
Mooring Line Damping Estimation for a Floating Wind Turbine
Directory of Open Access Journals (Sweden)
Dongsheng Qiao
2014-01-01
Full Text Available The dynamic responses of mooring line serve important functions in the station keeping of a floating wind turbine (FWT. Mooring line damping significantly influences the global motions of a FWT. This study investigates the estimation of mooring line damping on the basis of the National Renewable Energy Laboratory 5 MW offshore wind turbine model that is mounted on the ITI Energy barge. A numerical estimation method is derived from the energy absorption of a mooring line resulting from FWT motion. The method is validated by performing a 1/80 scale model test. Different parameter changes are analyzed for mooring line damping induced by horizontal and vertical motions. These parameters include excitation amplitude, excitation period, and drag coefficient. Results suggest that mooring line damping must be carefully considered in the FWT design.
Validation of Analytical Damping Ratio by Fatigue Stress Limit
Foong, Faruq Muhammad; Chung Ket, Thein; Beng Lee, Ooi; Aziz, Abdul Rashid Abdul
2018-03-01
The optimisation process of a vibration energy harvester is usually restricted to experimental approaches due to the lack of an analytical equation to describe the damping of a system. This study derives an analytical equation, which describes the first mode damping ratio of a clamp-free cantilever beam under harmonic base excitation by combining the transverse equation of motion of the beam with the damping-stress equation. This equation, as opposed to other common damping determination methods, is independent of experimental inputs or finite element simulations and can be solved using a simple iterative convergence method. The derived equation was determined to be correct for cases when the maximum bending stress in the beam is below the fatigue limit stress of the beam. However, an increasing trend in the error between the experiment and the analytical results were observed at high stress levels. Hence, the fatigue limit stress was used as a parameter to define the validity of the analytical equation.
Resummation and the gluon damping rate in hot QCD
International Nuclear Information System (INIS)
Pisarski, R.D.
1990-08-01
At high temperature a consistent perturbative expansion requires the resummation of an infinite subset of loop corrections into an effective expansion. This effective exansion is used to compute the gluon damping rate at leading order. 25 refs
INEL/USNRC pipe damping experiments and studies
International Nuclear Information System (INIS)
Ware, A.G.
1987-08-01
Since the previous paper on this subject presented at the 8th SMiRT Conference, the Idaho National Engineering Laboratory (INEL) has conducted further research on piping system damping for the United States Nuclear Regulatory Commission (USNRC). These efforts have included vibration tests on two laboratory piping systems at response frequencies up to 100 Hz, and damping data calculations from both of these two systems and from a third laboratory piping system test series. In addition, a statistical analysis was performed on piping system damping data from tests representative of seismic and hydrodynamic events of greater than minimal excitation. The results of this program will be used to assist regulators in establishing suitable damping values for use in dynamic analyses of nuclear piping systems, and in revising USNRC Regulatory Guide (RG) 1.61
Nonlinear damped Schrodinger equation in two space dimensions
Directory of Open Access Journals (Sweden)
Tarek Saanouni
2015-04-01
Full Text Available In this article, we study the initial value problem for a semi-linear damped Schrodinger equation with exponential growth nonlinearity in two space dimensions. We show global well-posedness and exponential decay.
Nonlinear time heteronymous damping in nonlinear parametric planetary systems
Czech Academy of Sciences Publication Activity Database
Hortel, Milan; Škuderová, Alena
2014-01-01
Roč. 225, č. 7 (2014), s. 2059-2073 ISSN 0001-5970 Institutional support: RVO:61388998 Keywords : nonlinear dynamics * planetary systems * heteronymous damping Subject RIV: JT - Propulsion, Motors ; Fuels Impact factor: 1.465, year: 2014
Mooring line damping estimation for a floating wind turbine.
Qiao, Dongsheng; Ou, Jinping
2014-01-01
The dynamic responses of mooring line serve important functions in the station keeping of a floating wind turbine (FWT). Mooring line damping significantly influences the global motions of a FWT. This study investigates the estimation of mooring line damping on the basis of the National Renewable Energy Laboratory 5 MW offshore wind turbine model that is mounted on the ITI Energy barge. A numerical estimation method is derived from the energy absorption of a mooring line resulting from FWT motion. The method is validated by performing a 1/80 scale model test. Different parameter changes are analyzed for mooring line damping induced by horizontal and vertical motions. These parameters include excitation amplitude, excitation period, and drag coefficient. Results suggest that mooring line damping must be carefully considered in the FWT design.
Mimicking an amplitude damping channel for Laguerre Gaussian Modes
CSIR Research Space (South Africa)
Dudley, Angela L
2010-10-01
Full Text Available An amplitude damping channel for Laguerre-Gaussian (LG) modes is presented. Experimentally the action of the channel on LG modes is in good agreement with that predicted theoretically....
Thermodynamic Damping in Porous Materials with Spherical Cavities
Directory of Open Access Journals (Sweden)
Sofia D. Panteliou
1997-01-01
Full Text Available When a material is subjected to an alternating stress field, there are temperature fluctuations throughout its volume due to the thermoelastic effect. The resulting irreversible heat conduction leads to entropy production that in turn is the cause of thermoelastic damping. An analytical investigation of the entropy produced during a vibration cycle due to the reciprocity of temperature rise and strain yielded the change of the material damping factor as a function of the porosity of the material. A homogeneous, isotropic, elastic bar of cylindrical shape is considered with uniformly distributed spherical cavities under alternating uniform axial stress. The analytical calculation of the dynamic characteristics of the porous structure yielded the damping factor of the bar and the material damping factor. Exsperimental results on porous metals are in good correlation with an analysis.
Squeeze-film damping characteristics of cantilever microresonators ...
African Journals Online (AJOL)
user
perturbation approach does not apply to cantilever plates because of ...... Direct coupling of electrostatic and structural domain has been achieved using ... forces are computed to obtain the modal squeeze stiffness and damping parameters.
An Approximate Method for Pitch-Damping Prediction
National Research Council Canada - National Science Library
Danberg, James
2003-01-01
...) method for predicting the pitch-damping coefficients has been employed. The CFD method provides important details necessary to derive the correlation functions that are unavailable from the current experimental database...
Damping properties of epoxy-based composite embedded with sol ...
Indian Academy of Sciences (India)
State Key Laboratory of Advanced Technology for Materials Synthesis and ... But the piezoelectric damping materials are gene- rally brittle, fragile and hard. ... radiation. The scanning rate was 4. ◦. /min. The surface mor- phologies were ...
Highly Damping Hard Coatings for Protection of Titanium Blades
National Research Council Canada - National Science Library
Movchan, Boris A; Ustinov, Anatolii I
2005-01-01
Sn-Cr-MgO system is used as an example to show the basic capability to produce by EBPVD protective metal-ceramic coatings with a high adhesion strength, high values of hardness and damping capacity...
Analisis Pembiayaan Kesehatan Keluarga Penderita Talasemia
Directory of Open Access Journals (Sweden)
Arif Kurniawan
2013-04-01
Full Text Available Pembiayaan kesehatan sekitar 146 (60% penderita talasemia di Banyumas, tahun 2011 ditanggung rumah tangga dalam bentuk pembayaran langsung (out of pocket payment. Penelitian ini bertujuan untuk menganalisis ability to pay, willingness to pay, dan need assessment pembiayaan kesehatan penderita talasemia di Kabupaten Banyumas. Jenis penelitian ini adalah observasional analitik dengan rancangan studi kasus. Penelitian ini menggunakan desain studi cross sectional dengan teknik pengambilan sampel simple random sampling. Jumlah sampel penelitian 30 responden yang mempunyai anggota keluarga penderita talasemia di Kabupaten Banyumas. Hasil penelitian menunjukkan keluarga penderita talasemia mempunyai ability to pay rata-rata adalah Rp34.448,8/bulan dan rata-rata willingness to pay pengobatan talasemia adalah Rp133.833,3/ bulan. Pola pembiayaan kesehatan talasemia di Kabupaten Banyumas menggunakan 93,3% Jaminan Kesehatan Masyarakat (Jamkesmas, 3,3% biaya sendiri, dan 3,3% asuransi kesehatan. Sebelum mendapatkan Jamkesmas, 90,0% responden membayar dengan out of pocket, berhutang, berhemat pada kebutuhan nonkesehatan, dan menjual perhiasan/sawah. Kebutuhan pelayanan kesehatan yang diharapkan keluarga penderita talasemia adalah konsultasi talasemia dan desain khusus ruang perawatan anak. Kebutuhan pembiayaan kesehatan keluarga penderita talasemia adalah uang transportasi ke rumah sakit sebagai bentuk biaya tidak langsung. Health financing of majority thalassemia patients, around 146 people (60% in Banyumas year 2011 is assured by Households in direct payments to health care providers (out-of-pocket payment. This study aimed to analyze the ability to pay, willingness to pay, and need assessment of health financing thalassemia in Banyumas. This research an analytic observation- Analisis Pembiayaan Kesehatan Keluarga Penderita Talasemia Health Financing Analysis of Thalassemia Patient Family Arif Kurniawan, Arih Diyaning Intiasari al with case study design
Reduced Order Models for Dynamic Behavior of Elastomer Damping Devices
Morin, B.; Legay, A.; Deü, J.-F.
2016-09-01
In the context of passive damping, various mechanical systems from the space industry use elastomer components (shock absorbers, silent blocks, flexible joints...). The material of these devices has frequency, temperature and amplitude dependent characteristics. The associated numerical models, using viscoelastic and hyperelastic constitutive behaviour, may become computationally too expensive during a design process. The aim of this work is to propose efficient reduced viscoelastic models of rubber devices. The first step is to choose an accurate material model that represent the viscoelasticity. The second step is to reduce the rubber device finite element model to a super-element that keeps the frequency dependence. This reduced model is first built by taking into account the fact that the device's interfaces are much more rigid than the rubber core. To make use of this difference, kinematical constraints enforce the rigid body motion of these interfaces reducing the rubber device model to twelve dofs only on the interfaces (three rotations and three translations per face). Then, the superelement is built by using a component mode synthesis method. As an application, the dynamic behavior of a structure supported by four hourglass shaped rubber devices under harmonic loads is analysed to show the efficiency of the proposed approach.
Hydrocarbon-based solution for drilling and damping wells
Energy Technology Data Exchange (ETDEWEB)
Orlov, G A; Davydova, A I; Dobroskok, B Ye; Kendis, M Sh; Salimov, M Kh; Zvagil' skiy, G Ye
1982-01-01
The proportions are, %: oil product 23-74.4; emulsifier 0.5-1.2; monoethanolamine 0.1-0.2 and the rest mineral water. The solution is prepared as follows: the oil product (a mixture of Romashkinskiy oilfield oil and bituminous distillate 1:1) is mixed with emulsifier (85%) and stabilizer (15%). Mineral water is gradually added to a density of 1.18 g/cm/sup 3/. Mixing stops upon reaching the desired value of breakdown voltage, characterizing a stable solution. This solution has a higher overall stability (electrostability 1.8-3.1 times higher) than the usual solution. Also it has higher structural mechanical properties at lesser viscosity. The solution remains rather stable even when clay powder is added at 700 g/1 added at temperatures up to 95/sup 0/. It breaks down at a clay powder content of 350 g/1 and a temperature of 70/sup 0/. The solution can be used for opening layers and damping wells, having 95/sup 0/ temperatures. It is useful for drilling horizons with unstable rock. The solution currently used is used for wells having 60/sup 0/ temperatures and for horizons that do not have unstable rock. Due to cheaper additives, the solution is 6.2 times cheaper per lm/sup 3/ than the one being used currently.
Water confinement effects on fuel assembly motion and damping
International Nuclear Information System (INIS)
Brenneman, B.; Shah, S.J.; Williams, G.T.; Strumpell, J.H.
2003-01-01
It has been established by other authors that the accelerations of the water confined by the reactor core baffle plates has a significant effect on the responses of all the fuel assemblies during LOCA or seismic transients. This particular effect is a consequence of the water being essentially incompressible, and thus experiencing the same horizontal accelerations as the imposed baffle plate motions. These horizontal accelerations of the fluid induce lateral pressure gradients that cause horizontal buoyancy forces on any submerged structures. These forces are in the same direction as the baffle accelerations and, for certain frequencies at least, tend to reduce the relative displacements between the fuel and baffle plates. But there is another confinement effect - the imposed baffle plate velocities must also be transmitted to the water. If the fuel assembly grid strips are treated as simple hydro-foils, these horizontal velocity components change the fluid angle of attack on each strip, and thus may induce large horizontal lift forces on each grid in the same direction as the baffle plate velocity. There is a similar horizontal lift due to inclined flow over the rods when axial flow is present. These combined forces appear to always reduce the relative displacements between the fuel and baffle plates for any significant axial flow velocity. Modeling this effect is very simple. It was shown in previous papers that the mechanism for the large fuel assembly damping due to axial flow may be the hydrodynamic forces on the grid strips, and that this is very well represented by discrete viscous dampers at each grid elevation. To include the imposed horizontal water velocity effects, on both the grids and rods, these dampers are simply attached to the baffle plate rather than 'ground'. The large flow-induced damping really acts in a relative reference frame rather than an absolute or inertial reference frame, and thus it becomes a flow-induced coupling between the fuel
On the Stochastic Wave Equation with Nonlinear Damping
International Nuclear Information System (INIS)
Kim, Jong Uhn
2008-01-01
We discuss an initial boundary value problem for the stochastic wave equation with nonlinear damping. We establish the existence and uniqueness of a solution. Our method for the existence of pathwise solutions consists of regularization of the equation and data, the Galerkin approximation and an elementary measure-theoretic argument. We also prove the existence of an invariant measure when the equation has pure nonlinear damping
Eddy damping effect of additional conductors in superconducting levitation systems
Energy Technology Data Exchange (ETDEWEB)
Jiang, Zhao-Fei; Gou, Xiao-Fan, E-mail: xfgou@hhu.edu.cn
2015-12-15
Highlights: • In this article, for the eddy current damper attached to the HTSC, we • quantitatively investigated the damping coefficient c, damping ratio, Joule heating of the copper damper, and the vibration frequency of the PM as well. • presented four different arrangements of the copper damper, and comparatively studied their damping effects and Joule heating, and finally proposed the most advisable arrangement. - Abstract: Passive superconducting levitation systems consisting of a high temperature superconductor (HTSC) and a permanent magnet (PM) have demonstrated several fascinating applications such as the maglev system, flywheel energy storage. Generally, for the HTSC–PM levitation system, the HTSC with higher critical current density J{sub c} can obtain larger magnetic force to make the PM levitate over the HTSC (or suspended below the HTSC), however, the process of the vibration of the levitated PM, provides very limited inherent damping (essentially hysteresis). To improve the dynamic stability of the levitated PM, eddy damping of additional conductors can be considered as the most simple and effective approach. In this article, for the HTSC–PM levitation system with an additional copper damper attached to the HTSC, we numerically and comprehensively investigated the damping coefficient c, damping ratio, Joule heating of the copper damper, and the vibration frequency of the PM as well. Furthermore, we comparatively studied four different arrangements of the copper damper, on the comprehensive analyzed the damping effect, efficiency (defined by c/V{sub Cu}, in which V{sub Cu} is the volume of the damper) and Joule heating, and finally presented the most advisable arrangement.
Updating Stiffness and Hysteretic Damping Matrices Using Measured Modal Data
Directory of Open Access Journals (Sweden)
Jiashang Jiang
2018-01-01
Full Text Available A new direct method for the finite element (FE matrix updating problem in a hysteretic (or material damping model based on measured incomplete vibration modal data is presented. With this method, the optimally approximated stiffness and hysteretic damping matrices can be easily constructed. The physical connectivity of the original model is preserved and the measured modal data are embedded in the updated model. The numerical results show that the proposed method works well.
Updating Stiffness and Hysteretic Damping Matrices Using Measured Modal Data
Jiashang Jiang; Yongxin Yuan
2018-01-01
A new direct method for the finite element (FE) matrix updating problem in a hysteretic (or material) damping model based on measured incomplete vibration modal data is presented. With this method, the optimally approximated stiffness and hysteretic damping matrices can be easily constructed. The physical connectivity of the original model is preserved and the measured modal data are embedded in the updated model. The numerical results show that the proposed method works well.
Landau damping of dust acoustic solitary waves in nonthermal plasmas
Ghai, Yashika; Saini, N. S.; Eliasson, B.
2018-01-01
Dust acoustic (DA) solitary and shock structures have been investigated under the influence of Landau damping in a dusty plasma containing two temperature nonthermal ions. Motivated by the observations of Geotail spacecraft that reported two-temperature ion population in the Earth's magnetosphere, we have investigated the effect of resonant wave-particle interactions on DA nonlinear structures. The Korteweg-de Vries (KdV) equation with an additional Landau damping term is derived and its analytical solution is presented. The solution has the form of a soliton whose amplitude decreases with time. Further, we have illustrated the influence of Landau damping and nonthermality of the ions on DA shock structures by a numerical solution of the Landau damping modified KdV equation. The study of the time evolution of shock waves suggests that an initial shock-like pulse forms an oscillatory shock at later times due to the balance of nonlinearity, dispersion, and dissipation due to Landau damping. The findings of the present investigation may be useful in understanding the properties of nonlinear structures in the presence of Landau damping in dusty plasmas containing two temperature ions obeying nonthermal distribution such as in the Earth's magnetotail.
Damping of elastic waves in crystals with impurities
International Nuclear Information System (INIS)
Lemanov, V.V.; Petrov, A.V.; Akhmedzhanov, F.R.; Nasyrov, A.N.
1979-01-01
Elastic wave damping and thermal conductivity of NaCl-NaBr and Y 3 AL 5 O 12 crystals with Er impurity has been examined. The experimental results on a decrease in elastic wave damping in such crystals are analyzed in the framework of the Ahiezer damping theory. The measurements were made in the frequency range of 300-1500 MHz in propagation of longitudinal and transverse elastic waves along the [100] and [110] directions. At 10 % concentration of erbium impurity the transverse wave damping decreases by a factor of three, and for longitudinal waves by a factor of two in NaBr:Cl crystals, and by approximately 10 and 30 % for NaBr:Cl and Y 3 Al 5 O 12 :Er crystals, respectively. In Y 3 Al 5 O 12 crystals, unlike NaCl-NaBr crystals, no noticeable anisotropy of damping is observed. The transVerse wave damping in impurity crystals has been shown to increase significantly with decreasing temperature and increasing the impurity concentration
Significance of non-classical damping in seismic qualification of equipment and piping
Energy Technology Data Exchange (ETDEWEB)
Gupta, Abhinav, E-mail: agupta1@ncsu.edu; Bose, Mrinal K.
2017-06-15
Highlights: • Damping in coupled building-piping or building-equipment systems is nonlclassical. • Significance of nonclassical damping is illustrated. • Classical damping assumption can over predict or under predict response. • Significance of nonclassical damping increases for very light secondary systems. • Composite modal damping is another form of classical damping. - Abstract: This paper presents a discussion on the significance of non-classical damping in coupled primary-secondary systems such as building-equipment or building-piping. Closed-form expressions are used to illustrate that the effect of non-classical damping is significant in systems with tuned or nearly tuned uncoupled modes when the mass-interaction is sufficiently small. Further, simple primary-secondary systems are used to illustrate that composite modal damping is another form of classical damping for which the transformed damping matrix, obtained after pre- and post-multiplication of the damping matrix with the modal matrix, contains only diagonal terms. Both the composite and the classical damping give almost identical results that can be much different from the corresponding results for non-classical damping. Finally, it is shown that consideration of classical damping (ignoring the off-diagonal terms) can give excessively conservative results in nearly tuned primary-secondary systems. For perfectly tuned primary-secondary systems, however, classical damping can give responses that are much lower than what they should be.
International Nuclear Information System (INIS)
Gao, Yuan; Wang, Xiaoping; Liu, Meijun; Xi, Xue; Zhang, Xin; Jia, Demin
2014-01-01
Highlights: • MMT and XSBR display synergic effect on protecting HP1098 from being extracted. • A new hindered phenol HP1098 was used to prepare damping material. • Effects of three preparation methods on the material properties were studied. - Abstract: Three methods of blending, including direct blending, melt blending and latex blending, were introduced to disperse sodium based montmorillonite (Na-MMT) and N,N′-hexane-1,6-diylbis{3-(5-di-tert-butyl-4-hydroxyphenyl-propionamide)} (HP1098) into the carboxylated styrene butadiene (XSBR) matrix. Small angle X-ray Diffraction testing indicated that melting Na-MMT with HP1098 enlarged the d-spacing of Na-MMT, which was further enlarged by mechanical blending with XSBR, and this led to homogeneous dispersion of Na-MMT and HP1098, which was indicated by Transmission Electronic Microscopy; latex blending was found most advantageous in dispersing HP1098 which was essential for improved damping performance. Dynamic Mechanical Analysis was utilized to characterize damping properties, and enhanced static mechanical properties were presumably originated from molecule chains being intercalated into the enlarged galleries of Na-MMT by mechanical blending. Formation of hydrogen bonds was observed by Fourier Transformation Infrared Spectrum and was supposed to be responsible for exceptional damping performance at elevated temperature. Extraction measurement of XSBR/Na-MMT/HP1098 composite indicated that XSBR and Na-MMT showed synergic effect in protecting HP1098 molecules from being extracted, which is a promising method in preparing rubber/hindered phenol damping materials with improved extraction resistance, whereby increasing the performance stability and lifespan of the composite materials. Additional advantage of this type of materials is better processability and shortened vulcanization process
Energy Technology Data Exchange (ETDEWEB)
Rubin, David L. [Cornell Univ., Ithaca, NY (United States). Dept. of Physics
2015-01-23
Accelerators that collide high energy beams of matter and anti-matter are essential tools for the investigation of the fundamental constituents of matter, and the search for new forms of matter and energy. A “Linear Collider” is a machine that would bring high energy and very compact bunches of electrons and positrons (anti-electrons) into head-on collision. Such a machine would produce (among many other things) the newly discovered Higgs particle, enabling a detailed study of its properties. Among the most critical and challenging components of a linear collider are the damping rings that produce the very compact and intense beams of electrons and positrons that are to be accelerated into collision. Hot dilute particle beams are injected into the damping rings, where they are compressed and cooled. The size of the positron beam must be reduced more than a thousand fold in the damping ring, and this compression must be accomplished in a fraction of a second. The cold compact beams are then extracted from the damping ring and accelerated into collision at high energy. The proposed International Linear Collider (ILC), would require damping rings that routinely produce such cold, compact and intense beams. The goal of the Cornell study was a credible design for the damping rings for the ILC. Among the technical challenges of the damping rings; the development of instrumentation that can measure the properties of the very small beams in a very narrow window of time, and mitigation of the forces that can destabilize the beams and prevent adequate cooling, or worse lead to beam loss. One of the most pernicious destabilizing forces is due to the formation of clouds of electrons in the beam pipe. The electron cloud effect is a phenomenon in particle accelerators in which a high density of low energy electrons, build up inside the vacuum chamber. At the outset of the study, it was anticipated that electron cloud effects would limit the intensity of the positron ring
International Nuclear Information System (INIS)
Simpson, P.W.G.
1986-10-01
Retention of the mechanical integrity of fuel element assemblies during dry storage forms part of the strategy for any dry-store and is important for the ease of eventual reprocessing or disposal. This report describes a number of corrosion experiments which have been carried out on coupons of unirradiated CAGR fuel cladding steel which have been contaminated with simulated pond water. Two potential dry-store problem areas have been addressed. First is the possibility of failure of the dry-store mild steel container, allowing damp air to replace the nominally dry argon cover gas. Second is the possibility of water-logged failed fuel being inadvertently containerised giving rise to a humid argon atmosphere within the dry-store container. Specimens of niobium stabilised and titanium nitride strengthened CAGR fuel cladding steels in virgin, pre-oxidised and laboratory sensitised states have been exposed at temperatures of 150 0 C and 400 0 C, to air saturated with water at 10 0 C and to argon saturated at 25 0 C. Most specimens were contaminated with simulated pond water deposits containing chloride anion concentrations up to 10 ppm. No deleterious effects were observed either gravimetrically or metallographically after exposures between 10039 hours and 13152 hours. However, the absence of stress and radiation in these experiments means that caution should be exercised in applying the results to situations in which those conditions are present. (author)
Analisis Komoditi Unggulan Subsektor Tanaman Pangan di Sumatera Utara Tahun 2010 – 2014
Sinaga, Terry Praganda
2016-01-01
Tujuan penelitian ini adalah untuk mengetahui perkembangan produksi komoditi tanaman pangan selama periode tersebut sehingga dapat menganalisis komoditi subsektor tanaman pangan yang menjadi unggulan di Sumatera Utara. Komoditi unggulan tersebut juga dijabarkan untuk setiap kabupatem/kota yang ada di Sumatera Utara. Metode yang digunakan yaitu secara Convenience Sampling, dan metode analisis data dengan menggunakan analisis Location Quotient. Hasil penelitian menyimpulkan ba...
ANALISIS KINERJA KEUANGAN PERUSAHAAN PT. ASURANSI JIWASRAYA (PERSERO) CABANG SULAWESI SELATAN
ARIANTY, ASTRI
2012-01-01
ANALISIS KINERJA KEUANGAN PERUSAHAAN PT. ASURANSI JIWASRAYA (PERSERO) CABANG SULAWESI SELATAN COMPANY FINANCIAL PERFORMANCE ANALYSIS PT. INSURANCE JIWASRAYA (LIMITED) SOUTH BRANCH SULAWESI Astri Arianty Prof. Dr. H. Muhammad Ali, SE., M.S Drs. Armayah Sida, M.Si Analisis terhadap kinerja keuangan perusahaan sangat penting dilakukan untuk mengetahui sejauh mana tingkat pencapaian yang telah diperoleh perusahaan sebagaimana tujuan perusahaan dalam menjalankan proses produk...
Calculations of the electron-damping force on moving-edge dislocations
International Nuclear Information System (INIS)
Mohri, T.
1982-11-01
Dynamic effect of a moving dislocation has been recognized as one of essential features of deformation behavior at very low temperatures. Damping mechanisms are the central problems in this field. Based on the free-electron-gas model, the electron-damping force (friction force) on a moving-edge dislocation in a normal state is estimated. By applying classical MacKenzie-Sondheimer's procedures, the electrical resistivity caused by a moving dislocation is first estimated, and the damping force is calculated as a Joule-heat-energy dissipation. The calculated values are 3.63x10 - 6 , 7.62x10 - 7 and 1.00x10 - 6 [dyn sec/cm - 2 ] for Al, Cu and Pb, respectively. These values show fairly good agreements as compared with experimental results. Also, numerical calculations are carried out to estimate magnetic effects caused by a moving dislocation. The results are negative and any magnetic effects are not expected. In order to treat deformation behavior at very low temperatures, a unification of three important deformation problems is attempted and a fundamental equation is derived
International Nuclear Information System (INIS)
Tohsophon, T.; Huepkes, J.; Calnan, S.; Reetz, W.; Rech, B.; Beyer, W.; Sirikulrat, N.
2006-01-01
The damp heat stability and subsequent vacuum annealing behavior of aluminum doped zinc oxide (AZO) films was investigated using Hall effect measurements, X-ray diffraction (XRD) and optical spectrometry techniques. The AZO films were deposited on glass or silicon wafers using reactive and non-reactive magnetron sputtering from metallic and ceramic targets, respectively. Additionally, we characterized surface textured AZO films, which are used as light scattering transparent conductive oxide (TCO) in silicon thin film solar cells. For all films a degradation of the electrical film properties was found after the damp heat treatment. For thick compact films, with large grain size, only a small increase in the electrical resistivity was observed, whereas less compact films prepared at high deposition pressures or very thin films (< 300 nm) showed an increase in resistivity by up to a factor of three already after 300 h. The conductivity degradation during damp heat treatment could be largely reversed by annealing in vacuum. However, annealing temperatures of at least 150 deg. C were required. Possible mechanisms explaining the experimental results are discussed
Energy Technology Data Exchange (ETDEWEB)
Thomsen, K.; Thirstrup Petersen, J. [Forskningscenter Risoe (Denmark); Nim, E. [Bonus Energy A/S (Denmark); Oeye, S. [Danmarks Tekniske Univ. (Denmark); Pedersen, B. [LM Glasfiber A/S (Denmark)
2000-01-01
The main result of the investigation is a newly developed method to identify the effective damping for the edgewise blade mode shape for wind turbines. The method consists of an exciter mechanism which makes it possible to excite the edgewise blade mode shapes from the wind turbine nacelle and furthermore of an analysis method, which enables a straightforward determination of the damping. The analysis method is based on a local blade whirl description of the edgewise blade vibrations. The method is verified on a Bonus wind turbine and for this specific turbine the effective damping for edgewise blade vibrations has been determined. The results have been compared with aeroelastic simulations. The potential of the method is that the results can support the further development of aeroelastic models and fine tuning of parameters of importance of the edgewise blade vibration problem and thus improve the certainty in the predicted risk of vibrations. Furthermore, the method can be used for experimental investigation of the risk of edgewise blade vibrations for a specific turbine. (au)
Superelastic behavior and damping capacity of CuAlBe alloys
International Nuclear Information System (INIS)
Montecinos, Susana; Moroni, Maria Ofelia; Sepulveda, Aquiles
2006-01-01
Shape memory alloys (SMAs) showing the superelastic effect, dissipate energy through hysteretic cycles up to large strain amplitudes, without remnant strains after unloading. This effect is associated with a reversible stress-induced martensitic transformation. In this paper, the behavior of copper-based SMAs is examined, with the perspective of potential applications in seismic-energy dissipative devices. In particular, two different compositions of CuAlBe are characterized using chemical analysis, differential scanning calorimetry (DSC), light and scanning electron microscopy and X-rays diffraction. Mechanical and hysteretic damping properties are determined from cyclic tensile and tension-compression tests, for different strain amplitudes and frequencies. Both alloys show superelastic behavior, although hysteresis loops differ, due to differences in the composition and transformation phase temperatures. Equivalent damping up to 5% was obtained for the largest strain imposed. Frequency, in the range of interest for seismic applications, had a small influence on the damping values. It is concluded that alloy Cu-11.8 wt.% Al-0.5 wt.% Be best exhibited properties for the application intended
Saturation of a toroidal Alfvén eigenmode due to enhanced damping of nonlinear sidebands
Todo, Y.; Berk, H. L.; Breizman, B. N.
2012-09-01
This paper examines nonlinear magneto-hydrodynamic effects on the energetic particle driven toroidal Alfvén eigenmode (TAE) for lower dissipation coefficients and with higher numerical resolution than in the previous simulations (Todo et al 2010 Nucl. Fusion 50 084016). The investigation is focused on a TAE mode with toroidal mode number n = 4. It is demonstrated that the mechanism of mode saturation involves generation of zonal (n = 0) and higher-n (n ⩾ 8) sidebands, and that the sidebands effectively increase the mode damping rate via continuum damping. The n = 0 sideband includes the zonal flow peaks at the TAE gap locations. It is also found that the n = 0 poloidal flow represents a balance between the nonlinear driving force from the n = 4 components and the equilibrium plasma response to the n = 0 fluctuations. The spatial profile of the n = 8 sideband peaks at the n = 8 Alfvén continuum, indicating enhanced dissipation due to continuum damping.
Directory of Open Access Journals (Sweden)
Long Chen
2016-01-01
Full Text Available Active suspension has not been popularized for high energy consumption. To address this issue, this paper introduces the concept of a new kind of suspension. The linear motor is considered to be integrated into an adjustable shock absorber to form the hybrid active semiactive suspension (HASAS. To realize the superiority of HASAS, its energy consumption and regeneration mechanisms are revealed. And the system controller which is composed of linear quadratic regulator (LQR controller, mode decision and switch controller, and the sliding mode control based thrust controller is developed. LQR controller is designed to maintain the suspension control objectives, while mode decision and switch controller decides the optimal damping level to tune motor thrust. The thrust controller ensures motor thrust tracking. An adjustable shock absorber with three regulating levels to be used in HASAS is trial produced and tested to obtain its working characteristics. Finally, simulation analysis is made with the experimental three damping characteristics. The impacts of adjustable damping on the motor force and energy consumption are investigated. Simulation results demonstrate the advantages of HASAS in energy conservation with various suspension control objectives. Even self-powered active control and energy regenerated to the power source can be realized.
SBS symptoms in relation to dampness and ventilation in inspected single-family houses in Sweden.
Smedje, Greta; Wang, Juan; Norbäck, Dan; Nilsson, Håkan; Engvall, Karin
2017-10-01
To investigate the relationships between symptoms compatible with the sick building syndrome (SBS) in adults and building dampness and ventilation in single-family houses. Within the Swedish BETSI study, a national sample of single-family houses were inspected by professional building experts, and adults living in the houses answered a questionnaire on SBS. Relationships between building factors and SBS were analysed using logistic regression. Of the respondents, 23% reported having had weekly SBS symptoms during the last three months. A large proportion of houses exhibited building or construction problems. In total, 40% of houses had dampness problems in the foundation, and this was related to a higher prevalence of both mucous and dermal symptoms, and any SBS symptoms. Furthermore, high air humidity was related to more symptoms, with the relationship with absolute humidity being stronger than that with relative humidity or moisture load. Symptoms were also more prevalent in houses with a high U value, reflecting a poor thermal insulation. Compared to natural ventilation, living in a house with mechanical supply and exhaust ventilation was related to a lower prevalence of general symptoms and any SBS symptoms, but there were only weak associations between measured air exchange rate and symptoms. A large proportion of single-family houses have dampness problems in the foundation, and pollutants may enter the living space of the house and affect the health of the occupants. Furthermore, absolute air humidity should be measured more often in indoor air studies.
RF cavity R and D at LBNL for the NLC Damping Rings, FY2000/2001
International Nuclear Information System (INIS)
Rimmer, R.A.; Atkinson, D.; Corlett, J.N.; Koehler, G.; Li, D.; Hartman, N.; Rasson, J.; Saleh, T.; Weidenbach, W.
2001-01-01
This report contains a summary of the R and D activities at LBNL on RF cavities for the NLC damping rings during fiscal years 2000/2001. This work is a continuation of the NLC RF system R and D of the previous year [1]. These activities include the further optimization and fine tuning of the RF cavity design for both efficiency and damping of higher-order modes (HOMs). The cavity wall surface heating and stresses were reduced at the same time as the HOM damping was improved over previous designs. Final frequency tuning was performed using the high frequency electromagnetic analysis capability in ANSYS. The mechanical design and fabrication methods have been developed with the goals of lower stresses, fewer parts and simpler assembly compared to previous designs. This should result in substantial cost savings. The cavity ancillary components including the RF window, coupling box, HOM loads, and tuners have been studied in more detail. Other cavity options are discussed which might be desirable to either further lower the HOM impedance or increase the stored energy for reduced transient response. Superconducting designs and the use of external ''energy storage'' cavities are discussed. A section is included in which the calculation method is summarized and its accuracy assessed by comparisons with the laboratory measurements of the PEP-II cavity, including errors, and with the beam-sampled spectrum
Using Field-Particle Correlations to Diagnose the Collisionless Damping of Plasma Turbulence
Howes, Gregory; Klein, Kristropher
2016-10-01
Plasma turbulence occurs ubiquitously throughout the heliosphere, yet our understanding of how turbulence governs energy transport and plasma heating remains incomplete, constituting a grand challenge problem in heliophysics. In weakly collisional heliospheric plasmas, such as the solar corona and solar wind, damping of the turbulent fluctuations occurs due to collisionless interactions between the electromagnetic fields and the individual plasma particles. A particular challenge in diagnosing this energy transfer is that spacecraft measurements are typically limited to a single point in space. Here we present an innovative field-particle correlation technique that can be used with single-point measurements to estimate the energization of the plasma particles due to the damping of the electromagnetic fields, providing vital new information about this how energy transfer is distributed as a function of particle velocity. This technique has the promise to transform our ability to diagnose the kinetic plasma physical mechanisms responsible for not only the damping of turbulence, but also the energy conversion in both collisionless magnetic reconnection and particle acceleration. The work has been supported by NSF CAREER Award AGS-1054061, NSF AGS-1331355, and DOE DE-SC0014599.
Directory of Open Access Journals (Sweden)
Saeed Soleymani
2016-01-01
Full Text Available This paper Analytically investigates the effects of system and controller parameters and operating conditions on the dynamic and transient behavior of wind turbines (WTs with doubly-fed induction generators (DFIGs under voltage dips and wind speed fluctuations. Also, it deals with the design considerations regarding rotor and speed controllers. The poorly damped electrical and mechanical modes of the system are identified, and the effects of system parameters, and speed/rotor controllers on these modes are investigated by modal and sensitivity analyses. The results of theoretical studies are verified by time domain simulations. It is found that the dynamic behavior of the DFIG-based WT under voltage dips is strongly affected by the stator dynamics. Further, it is shown that the closed loop bandwidth of the rotor current control, rotor current damping, DFIG power factor and the rotor back-emf voltages have high impact on the stator modes and consequently on the DFIG dynamic behavior. Moreover, it is shown that the dynamic behavior of DFIG-based WT under wind speed fluctuation is significantly dependent on the bandwidth and damping of speed control loop.
Current-induced damping of nanosized quantum moments in the presence of spin-orbit interaction
Mahfouzi, Farzad; Kioussis, Nicholas
2017-05-01
Motivated by the need to understand current-induced magnetization dynamics at the nanoscale, we have developed a formalism, within the framework of Keldysh Green function approach, to study the current-induced dynamics of a ferromagnetic (FM) nanoisland overlayer on a spin-orbit-coupling (SOC) Rashba plane. In contrast to the commonly employed classical micromagnetic LLG simulations the magnetic moments of the FM are treated quantum mechanically. We obtain the density matrix of the whole system consisting of conduction electrons entangled with the local magnetic moments and calculate the effective damping rate of the FM. We investigate two opposite limiting regimes of FM dynamics: (1) The precessional regime where the magnetic anisotropy energy (MAE) and precessional frequency are smaller than the exchange interactions and (2) the local spin-flip regime where the MAE and precessional frequency are comparable to the exchange interactions. In the former case, we show that due to the finite size of the FM domain, the "Gilbert damping" does not diverge in the ballistic electron transport regime, in sharp contrast to Kambersky's breathing Fermi surface theory for damping in metallic FMs. In the latter case, we show that above a critical bias the excited conduction electrons can switch the local spin moments resulting in demagnetization and reversal of the magnetization. Furthermore, our calculations show that the bias-induced antidamping efficiency in the local spin-flip regime is much higher than that in the rotational excitation regime.
Identifiksi Sebaran Litologi berdasarkan Analisis Data Resistivitas di Gunung Wungkal
Nurul Dzakiya; MGS. Dwiki Nugraha; Nenden L. Sidik; Trias Galena
2017-01-01
Analisis data untuk mengidentifikasi sebaran litologi yang memiliki potensi bahan galian industri di Daerah Gunung Wungkal Yogyakarta dengan menggunakan metode resistivitas dan survei geologi permukaan telah dilakukan. Hasil korelasi kedua data tersebut menunjukkan sebaran litologi merupakan pelapukan intrusi batuan beku yang kemudian menghasilkan material lempung (6,0-10 m), lempung pasiran (11-30 m) dan lapukan batuan diorit (30-55 m) yang berada di kedalaman berbeda. Ketebalan batuan di pe...
Analisis Sikap Konsumen terhadap Produk Fashion Lokal dan Impor
Setiawan, Evelyn
2014-01-01
Abstrak: Analisis Sikap Konsumen Terhadap Produk Fashion Lokal dan Impor. Penelitian ini bertujuan untuk menganalisis sikap konsumen terhadap produk fashion lokal dan impor yang akan berpengaruh terhadap keputusan konsumsi. Sampel yang akan digunakan dalam penelitian ini adalah 1.000 mahasiswa dari 10 perguruan tinggi swasta terbesar di Surabaya. Pengambilan data dilakukan dengan metode kuesioner. Hasil pengujian statistik menunjukkan bahwa sebagian besar mahasiswa di Surabaya merasa bangga d...
Uso de Analisis de Covarianza (ANCOVA en investigacion cientifica.
Directory of Open Access Journals (Sweden)
Badii, M.H.
2008-01-01
Full Text Available The basics of the ANalisis of COVAriance (ANCOVA are given. The objectives and the application of ANCOVA are laid out. Techniques for the estimation of contrasts and for the control and reduction of the degree of error are discussed. The application of a simple ANCOVA using real data is highlighted. The application of this technique in fixing the auxiliary variable in experimentation is emphasized.