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PIEZOELECTRIC POWER SCAVENGING OF MECHANICAL VIBRATION ENERGY

PIEZOELECTRIC POWER SCAVENGING OF MECHANICAL VIBRATION ENERGY PIEZOELECTRIC POWER SCAVENGING OFPIEZOELECTRIC POWER SCAVENGING OF MECHANICAL VIBRATION ENERGYMECHANICAL VIBRATION ENERGY CE 511- Structural

Ervin, Elizabeth K.

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A micropower programmable DSP powered using a MEMS-based vibration-to-electric energy converter

An ultra-low-power programmable DSP for sensor applications enables systems to be powered by ambient vibration. The three-chip system consists of a MEMS transducer that converts vibration to a voltage delivered to a conversion IC. The conversion IC creates a stable power supply that provides energy to the sensor DSP load. The system exploits ambient mechanical vibration as its energy source

R. Amirtharajah; S. Meninger; J. O. Mur-Miranda; A. Chandrakasan; J. Lang

2000-01-01

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Output power of piezoelectric MEMS vibration energy harvesters under random oscillations

NASA Astrophysics Data System (ADS)

Environmental vibrations include random oscillations of different frequencies and amplitudes. Energy harvesters recover the energy associated with these vibrations. Properties of the vibrations and output power are characterized for cantilever-type piezoelectric vibration energy harvesters using (100)-orientated BiFeO3 films subject to both ideal and random oscillations. The displacement and output power under random oscillations were smaller than those under ideal oscillations. This decrease originates with the decreasing acceleration of the fundamental wave with the spurious component having little influence on the resonance response.

Kariya, K.; Yoshimura, T.; Murakami, S.; Fujimura, N.

2014-11-01

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Improving power output for vibration-based energy scavengers

Pervasive networks of wireless sensor and communication nodes have the potential to significantly impact society and create large market opportunities. For such networks to achieve their full potential, however, we must develop practical solutions for self-powering these autonomous electronic devices. We've modeled, designed, and built small cantilever-based devices using piezoelectric materials that can scavenge power from low-level ambient vibration sources.

Shad Roundy; Eli S. Leland; Jessy Baker; Eric Carleton; Elizabeth K. Reilly; Elaine Lai; Brian Otis; Jan M. Rabaey; Paul K. Wright; V. Sundararajan

2005-01-01

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NASA Astrophysics Data System (ADS)

The design of vibration energy harvesters (VEHs) is highly dependent upon the characteristics of the environmental vibrations present in the intended application. VEHs can be linear resonant systems tuned to particular frequencies or nonlinear systems with either bistable operation or a Duffing-type response. This paper provides detailed vibration data from a range of applications, which has been made freely available for download through the Energy Harvesting Network’s online data repository. In particular, this research shows that simulation is essential in designing and selecting the most suitable vibration energy harvester for particular applications. This is illustrated through C-based simulations of different types of VEHs, using real vibration data from a diesel ferry engine, a combined heat and power pump, a petrol car engine and a helicopter. The analysis shows that a bistable energy harvester only has a higher output power than a linear or Duffing-type nonlinear energy harvester with the same Q-factor when it is subjected to white noise vibration. The analysis also indicates that piezoelectric transduction mechanisms are more suitable for bistable energy harvesters than electromagnetic transduction. Furthermore, the linear energy harvester has a higher output power compared to the Duffing-type nonlinear energy harvester with the same Q factor in most cases. The Duffing-type nonlinear energy harvester can generate more power than the linear energy harvester only when it is excited at vibrations with multiple peaks and the frequencies of these peaks are within its bandwidth. Through these new observations, this paper illustrates the importance of simulation in the design of energy harvesting systems, with particular emphasis on the need to incorporate real vibration data.

Beeby, Stephen P.; Wang, Leran; Zhu, Dibin; Weddell, Alex S.; Merrett, Geoff V.; Stark, Bernard; Szarka, Gyorgy; Al-Hashimi, Bashir M.

2013-07-01

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Scaling and power density metrics of electromagnetic vibration energy harvesting devices

NASA Astrophysics Data System (ADS)

A review of the vibration energy harvesting literature has been undertaken with the goal of establishing scaling laws for experimentally demonstrated harvesting devices based on electromagnetic transduction. Power density metrics are examined with respect to scaling length, mass, frequency and drive acceleration. Continuous improvements in demonstrated power density of harvesting devices over the past decade are noted. Scaling laws are developed from observations that appear to suggest an upper limit to the power density achievable with current harvesting techniques.

Moss, Scott D.; Payne, Owen R.; Hart, Genevieve A.; Ung, Chandarin

2015-02-01

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NASA Astrophysics Data System (ADS)

The minimum transducer coupling to enable maximum theoretical power capture from vibration energy harvesters is derived, leading to the simple conclusion that the product of the transducer coupling coefficient and resonance quality factor must be greater than two. Maximum theoretical power capture is experimentally demonstrated on a micromachined piezoelectric energy harvester comprised of a 20 ?m thick epitaxial silicon cantilever with 800 nm thick lead-zirconate-titanate along the top surface and a bulk silicon mass at the tip. The coupling of these structures, although small (?2=0.0033), is entirely sufficient to enable maximum theoretical power capture owing to light damping (Q =906).

Kim, D.; Hewa-Kasakarage, N. N.; Yoon, S.; Hall, N. A.

2012-09-01

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Laser power and vibrational energy transfer in CO2 lasers

The decay of the laser power in the afterglow of a CO2 laser discharge is shown to be exponential when the upper laser level is excited directly by electrons. The decay time is shown to be a function of the rate coefficients describing the relaxation of the lower laser level. From power decay measurements it is found that the deactivation

K. Bulthuis

1973-01-01

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Broadband electromagnetic vibration energy harvesting system for powering wireless sensor nodes

NASA Astrophysics Data System (ADS)

This paper reports the design of an electromagnetic vibration energy harvesting system that provides high power density and broad bandwidth. The ‘double cell’ harvester was chosen as the generator for this system. In order to harvest power over a broad range of frequencies, four ‘double cell’ harvesters with varying resonances were incorporated in the system architecture. The average AC to regulated DC power conversion efficiency across the 4 Hz bandwidth was 78%, which is one of the highest reported magnitudes for an electromagnetic vibration harvesting system. The magnetic flux density variation within the double cell array was modeled using the finite element method and compared to a single cell with equivalent tip mass and magnet volume. The double cell array was found to generate a similar magnitude of power to a single cell but three times higher bandwidth. The average generator conversion efficiency for the double cell array was 45.3%, which approaches the maximum theoretical limit of 50%.

Marin, Anthony; Turner, John; Ha, Dong Sam; Priya, Shashank

2013-07-01

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A vibration-based MEMS piezoelectric energy harvester and power conditioning circuit.

This paper presents a micro-electro-mechanical system (MEMS) piezoelectric power generator array for vibration energy harvesting. A complete design flow of the vibration-based energy harvester using the finite element method (FEM) is proposed. The modal analysis is selected to calculate the resonant frequency of the harvester, and harmonic analysis is performed to investigate the influence of the geometric parameters on the output voltage. Based on simulation results, a MEMS Pb(Zr,Ti)O3 (PZT) cantilever array with an integrated large Si proof mass is designed and fabricated to improve output voltage and power. Test results show that the fabricated generator, with five cantilever beams (with unit dimensions of about 3 × 2.4 × 0.05 mm3) and an individual integrated Si mass dimension of about 8 × 12.4 × 0.5 mm3, produces a output power of 66.75 ?W, or a power density of 5.19 ?W?mm-3?g-2 with an optimal resistive load of 220 k? from 5 m/s2 vibration acceleration at its resonant frequency of 234.5 Hz. In view of high internal impedance characteristic of the PZT generator, an efficient autonomous power conditioning circuit, with the function of impedance matching, energy storage and voltage regulation, is then presented, finding that the efficiency of the energy storage is greatly improved and up to 64.95%. The proposed self-supplied energy generator with power conditioning circuit could provide a very promising complete power supply solution for wireless sensor node loads. PMID:24556670

Yu, Hua; Zhou, Jielin; Deng, Licheng; Wen, Zhiyu

2014-01-01

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Electric control of power extracting end-stop for MEMS vibration energy harvesting

NASA Astrophysics Data System (ADS)

This experimental work investigates a technique to further improve performance of vibration energy harvesters under displacement-constrained operation. Previously, a device concept based on end-stops acting as additional transducers was developed so that the harvested power can be increased beyond the power obtained from a conventional harvester of the same size. However, there is a range of tested acceleration amplitudes in which the transducing end- stop device performs worse than the conventional device. In this paper, an approach using electric control is used to optimize the end-stop transducer performance and thereby further improve the system effectiveness under displacement constrained operation. For example, the maximum power increases by a factor of 2.4 compared to that of a conventional prototype under the same operating conditions and constrained displacement amplitude, while this value was about 1.3 for the previous technique.

Truong, Binh Duc; Phu Le, Cuong; Halvorsen, Einar

2014-11-01

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Adaptive vibration energy harvesting

By scavenging energy from their local environment, portable electronic devices such as mobile phones, radios and wireless sensors can achieve greater run-times with potentially lower weight. Vibration energy harvesting is one such approach where energy from parasitic vibrations can be converted into electrical energy, through the use of piezoelectric and electromagnetic transducers. Parasitic vibrations come from a range of sources

Sam Behrens; John Ward; Josh Davidson

2007-01-01

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Downhole vibration sensing by vibration energy harvesting

This thesis outlines the design of a prototype electromagnetic induction vibration energy harvesting device for use in a downhole environment. First order models of the necessary components for a generic vibration energy ...

Trimble, A. Zachary

2007-01-01

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Adaptive vibration energy harvesting

NASA Astrophysics Data System (ADS)

By scavenging energy from their local environment, portable electronic devices such as mobile phones, radios and wireless sensors can achieve greater run-times with potentially lower weight. Vibration energy harvesting is one such approach where energy from parasitic vibrations can be converted into electrical energy, through the use of piezoelectric and electromagnetic transducers. Parasitic vibrations come from a range of sources such as wind, seismic forces and traffic. Existing approaches to vibration energy harvesting typically utilise a rectifier circuit, which is tuned to the resonant frequency of the harvesting structure and the dominant frequency of vibration. We have developed a novel approach to vibration energy harvesting, including adaption to non-periodic vibrations so as to extract the maximum amount of vibration energy available. Experimental results of an experimental apparatus using off-the-shelf transducer (i.e. speaker coil) show mechanical vibration to electrical energy conversion efficiencies of 27 - 34%. However, simulations of a more electro-mechanical efficient and lightly damped transducer show conversion efficiencies in excess of 80%.

Behrens, Sam; Ward, John; Davidson, Josh

2007-04-01

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Vibration Testing of Stirling Power Convertors

NASA Technical Reports Server (NTRS)

The NASA John H. Glenn Research Center (GRC) and the U.S. Department of Energy (DOE) are currently developing a high efficient, long life, free piston Stirling convertor for use as an advanced spacecraft power system for future NASA missions. As part of this development, a Stirling Technology Demonstrator Convertor (TDC), developed by Stirling Technology Company (STC) for DOE, was vibration tested at GRC s Structural Dynamics Laboratory (SDU7735) in November- December 1999. This testing demonstrated that the Stirling TDC is able to withstand the harsh random vibration (20 to 2000 Hertz) seen during a typical spacecraft launch and survive with no structural damage or functional power performance degradation, thereby enabling its usage in future spacecraft power systems. The Stirling Vibration Test Team at NASA GRC and STC personnel conducted tests on a single 55 electric watt TDC. The purpose was to characterize the TDC s structural response to vibration and determine if the TDC could survive the vibration criteria established by the Jet Propulsion Laboratory (JPL) for launch environments. The TDC was operated at full-stroke and full power conditions during the vibration testing. The TDC was tested in two orientations, with the direction of vibration parallel and perpendicular to the TDC s moving components (displacer and piston). The TDC successfully passed a series of sine and random vibration tests. The most severe test was a 12.3 Grms random vibration test (peak vibration level of 0.2 g2/Hz from 50 to 250 Hertz) with test durations of 3 minutes per axis. The random vibration test levels were chosen to simulate, with margin, the maximum anticipated launch vibration conditions. As a result of this very successful vibration testing and successful evaluations in other key technical readiness areas, the Stirling power system is now considered a viable technology for future application for NASA spacecraft missions. Possible usage of the Stirling power system would be to supply on- board electric spacecraft power for future NASA Deep-Space Missions, performing as an attractive alternative to Radioisotope Thermoelectric Generators (RTG). Usage of the Stirling technology is also being considered as the electric power source for future Mars rovers, whose mission profiles may exclude the use of photovoltaic power systems (such as exploring at high Martian latitudes or for missions of lengthy durations). GRC s Thermo-Mechanical Systems Branch (5490) provides Stirling technology expertise under a Space Act Agreement with the DOE. Additional vibration testing, by GRC s Structural Systems Dynamics Branch (7733, is planned to continue to demonstrate the Stirling power system s vibration capability as its technology and flight system designs progress.

Hughes, Bill; Goodnight, Thomas; McNelis, Mark E.; Suarez, Vicente J.; Schreiber, Jeff; Samorezov, Sergey

2003-01-01

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A Framework for Determining the Maximum Theoretical Power Output for a Given Vibration Energy

NASA Astrophysics Data System (ADS)

This paper outlines a mathematical framework to determine the upper bound on extractable power as a function of the forcing vibrations. In addition to determining the upper bound on power output, the method described provides insight into the dynamic transducer forces required to attain the upper bound. This relationship, between input vibration parameters and transducer force gives a critical first step in determining the optimal transducer architecture for a given vibration input. The method developed is applied to two specific vibration inputs; a single sinusoid, and the sum of two sinusoids. For the single sinusoidal case, the optimal transducer force is found to be that produced by a linear spring, resonant with the input frequency, and a linear viscous damper, with matched impedance to the mechanical damper. The solution to this first case was previously known, but has been used here to validate the methodology. The resulting transducer force for the input described by a sum of two sinusoids is found to be inherently time dependent. This time dependency shows that an active system can outperform a passive system. Furthermore, the upper bound on power output is shown to be twice that obtainable from a linear harvester centred at the lower of the two frequencies.

Heit, J.; Roundy, S.

2014-11-01

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Harvesting energy from non-ideal vibrations

Energy harvesting has drawn significant interest for its potential to power autonomous low-power applications. Vibration energy harvesting is particularly well suited to industrial condition sensing, environmental monitoring ...

Chang, Samuel C

2013-01-01

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NASA Astrophysics Data System (ADS)

A novel three-dimensional (3D) electret-based micro power generator with multiple vibration modes has been developed, which is capable of converting low-level ambient kinetic energy to electrical energy. The device is based on a rotational symmetrical resonator which consists of a movable disc-shaped seismic mass suspended by three sets of spiral springs. Experimental analysis shows that the proposed generator operates at an out-of-plane direction at mode I of 66 Hz and two in-plane directions at mode II of 75 Hz and mode III of 78.5 Hz with a phase difference of about 90°. A corona localized charging method is also proposed that employs a shadow mask and multiple discharge needles for the production of micro-sized electret array. From tests conducted at an acceleration of 0.05 g, the prototype can generate a maximum power of 4.8 nW, 0.67 nW and 1.2 nW at vibration modes of I, II and III, respectively. These values correspond to the normalized power densities of 16 µW cm-3 g-2, 2.2 µW cm-3 g-2 and 4 µW cm-3 g-2, respectively. The results show that the generator can potentially offer an intriguing alternative for scavenging low-level ambient energy from 3D vibration sources.

Tao, Kai; Liu, Shuwei; Woh Lye, Sun; Miao, Jianmin; Hu, Xiao

2014-06-01

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conversion of the vibration energy. This block is achieved with a successive approximation analogue to achieve optimal electromechanical conversion of the vibration energy. This control requires some (since Cres >> Cstore). Fig. 3 shows that the energy conversion is maximal for a particular range (U1, U2

Boyer, Edmond

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Vibration shape effects on the power output in piezoelectric vibro-impact energy harvesters

NASA Astrophysics Data System (ADS)

Vibro-Impcact harvesting devices are one concept to increase the bandwidth of resonant operated piezoelectric vibration generators. The fundamental setup is a piezoelectric bending element, where the deflection is limited by two stoppers. After starting the system in resonance operation the bandwidth increases towards higher frequencies as soon the deflection reach the stopper. If the stoppers are rigid, the frequency response gives constant amplitude for increasing frequencies, as long the system is treated as ideal one-DOF system with symmetric stoppers. In consequence, the bandwidth is theoretically unlimited large. However, such a system also has two major drawbacks, firstly the complicated startup mechanism and secondly the tendency to drop from the high constant branch in the frequency response on the much smaller linear branch if the system is disturbed. Nevertheless, the system has its application wherever the startup problem can be solved. Most modeling approaches utilize modal one-DOF models to describe the systems behavior and do not tread the higher harmonics of the beam. This work investigates the effects of the stoppers on the vibration shape of the piezoelectric beam, wherefore a finite element model is used. The used elements are one-dimensional two node elements based on the Timoshenko-beam theory. The finite element code is implemented in Matlab. The model is calculated utilizing time step integration for simulation, to reduce the computation time an auto-resonant calculation method is implemented. A control loop including positive feedback and saturation is used to create a self-excited system. Therefore, the system is always operated in resonance (on the backbone curve) and the frequency is a direct result of the computation. In this case tip velocity is used as feedback. This technique allows effective parametric studies. Investigated parameters include gap, excitation amplitude, tip mass as well as the stiffness of the stopper. The stress and strain distribution as well as the generated electrical power is analyzed with respect to the proper operation range.

Twiefel, Jens

2013-04-01

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Energy harvesting vibration sources for microsystems applications

This paper reviews the state-of-the art in vibration energy harvesting for wireless, self-powered microsystems. Vibration-powered generators are typically, although not exclusively, inertial spring and mass systems. The characteristic equations for inertial-based generators are presented, along with the specific damping equations that relate to the three main transduction mechanisms employed to extract energy from the system. These transduction mechanisms are: piezoelectric,

S P Beeby; M J Tudor; N M White

2006-01-01

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Powering a wireless sensor node with a vibration-driven piezoelectric energy harvester

NASA Astrophysics Data System (ADS)

This paper discusses the direct application of scavenged energy to power a wireless sensor platform. A trapezoidal piezoelectric harvester was designed for a specific machine tool application and tested for robustness and longevity as well as performance. The design focused on resonant performance and distributed strain concentrations at a given resonant frequency and acceleration. Critical issues of power coupling and conditioning between harvester and wireless platform were addressed. The wireless platform consisted of a sensor, controller, power conditioning circuitry, and a custom low power radio. The system transmitted a sensor sample once every 10 s in a scavenging environment of 0.25 g and 100 Hz for a system duty cycle of approximately 0.2%.

Reilly, Elizabeth K.; Burghardt, Fred; Fain, Romy; Wright, Paul

2011-12-01

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Piezoelectric cantilevers optimization for vibration energy harvesting

NASA Astrophysics Data System (ADS)

Vibration-based piezoelectric energy harvesters through the conversion of vibration energy to electrical energy has gained increasing attention over the past decade because of the reduced power requirements of small electronic components, especially in industrial condition monitoring applications where sensors may be embedded in machines. The structure parameters of cantilevered piezoelectric energy harvesters are of importance to maximize the output power in accordance with the characteristics of the ambient vibrations. Therefore, a piezoelectric cantilevers optimization method using finite element analysis and SPICE is proposed. This paper models piezoelectric cantilever using Hamilton principle and extracts the vibration modal parameters to establish the circuit model in SPICE. The numerical analysis is addressed to study the effect of parameters. Finally, the optimization analysis and experiment are carried out. The results verify that the optimized cantilevered piezoelectric energy harvesters can produce a 56V peak open-circuit voltage, and that the proposed method is suitable for optimization design of piezoelectric energy harvester.

Cao, Junyi; Zhou, Shengxi; Ren, Xiaolong; Cao, Binggang

2012-04-01

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Piezoelectric cantilevers optimization for vibration energy harvesting

NASA Astrophysics Data System (ADS)

Vibration-based piezoelectric energy harvesters through the conversion of vibration energy to electrical energy has gained increasing attention over the past decade because of the reduced power requirements of small electronic components, especially in industrial condition monitoring applications where sensors may be embedded in machines. The structure parameters of cantilevered piezoelectric energy harvesters are of importance to maximize the output power in accordance with the characteristics of the ambient vibrations. Therefore, a piezoelectric cantilevers optimization method using finite element analysis and SPICE is proposed. This paper models piezoelectric cantilever using Hamilton principle and extracts the vibration modal parameters to establish the circuit model in SPICE. The numerical analysis is addressed to study the effect of parameters. Finally, the optimization analysis and experiment are carried out. The results verify that the optimized cantilevered piezoelectric energy harvesters can produce a 56V peak open-circuit voltage, and that the proposed method is suitable for optimization design of piezoelectric energy harvester.

Cao, Junyi; Zhou, Shengxi; Ren, Xiaolong; Cao, Binggang

2011-11-01

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Extremely low-loss rectification methodology for low-power vibration energy harvesters

NASA Astrophysics Data System (ADS)

Because of its promise for the generation of wireless systems, energy harvesting technology using smart materials is the focus of significant reported effort. Various techniques and methodologies for increasing power extraction have been tested. One of the key issues with the existing techniques is the use of diodes in the harvesting circuits with a typical voltage drop of 0.7 V. Since most of the smart materials, and other transducers, do not produce large voltage outputs, this voltage drop becomes significant in most applications. Hence, there is a need for designing a rectification method that can convert AC to DC with minimal losses. This paper describes a new mechanical rectification scheme, designed using reed switches, in a full-bridge configuration that shows the capability of working with signals from millivolts to a few hundred volts with extremely low losses. The methodology has been tested for piezoelectric energy harvesters undergoing mechanical excitation.

Tiwari, R.; Ryoo, K.; Schlichting, A.; Garcia, E.

2013-06-01

26

Wireless Inductive Power Device Suppresses Blade Vibrations

NASA Technical Reports Server (NTRS)

Vibration in turbomachinery can cause blade failures and leads to the use of heavier, thicker blades that result in lower aerodynamic efficiency and increased noise. Metal and/or composite fatigue in the blades of jet engines has resulted in blade destruction and loss of lives. Techniques for suppressing low-frequency blade vibration, such as gtuned circuit resistive dissipation of vibratory energy, h or simply "passive damping," can require electronics incorporating coils of unwieldy dimensions and adding unwanted weight to the rotor. Other approaches, using vibration-dampening devices or damping material, could add undesirable weight to the blades or hub, making them less efficient. A wireless inductive power device (WIPD) was designed, fabricated, and developed for use in the NASA Glenn's "Dynamic Spin Rig" (DSR) facility. The DSR is used to simulate the functionality of turbomachinery. The relatively small and lightweight device [10 lb (approx.=4.5 kg)] replaces the existing venerable and bulky slip-ring. The goal is the eventual integration of this technology into actual turbomachinery such as jet engines or electric power generators, wherein the device will facilitate the suppression of potentially destructive vibrations in fan blades. This technology obviates slip rings, which require cooling and can prove unreliable or be problematic over time. The WIPD consists of two parts: a remote element, which is positioned on the rotor and provides up to 100 W of electrical power to thin, lightweight piezoelectric patches strategically placed on/in fan blades; and a stationary base unit that wirelessly communicates with the remote unit. The base unit supplies inductive power, and also acts as an input and output corridor for wireless measurement, and active control command to the remote unit. Efficient engine operation necessitates minimal disturbance to the gas flow across the turbine blades in any effort to moderate blade vibration. This innovation makes it possible to moderate vibration on or in turbomachinery blades by providing 100 W of wireless electrical power and actuation control to thin, lightweight vibration-suppressing piezoelectric patches (eight actuation and eight sensor patches in this prototype, for a total of 16 channels) positioned strategically on the surface of, or within, titanium fan blades, or embedded in composite fan blades. This approach moves significantly closer to the ultimate integration of "active" vibration suppression technology into jet engines and other turbomachinery devices such as turbine electrical generators used in the power industry. The novel feature of this device is in its utilization of wireless technology to simultaneously sense and actively control vibration in rotating or stationary turbomachinery blades using piezoelectric patches. In the past, wireless technology was used solely for sensing and diagnostics. This technology, however, will accomplish much more, in terms of simultaneously sensing, suppressing blade vibration, and making it possible for detailed study of vibration impact in turbomachinery blades.

Morrison, Carlos R.; Provenza, Andrew J.; Choi, Benjamin B.; Bakhle, Milind A.; Min, James B.; Stefko, George L.; Duffy, Kirsten P.; Fougers, Alan J.

2011-01-01

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Nonperturbative vibrational energy relaxation effects on vibrational line shapes

Nonperturbative vibrational energy relaxation effects on vibrational line shapes Shilong Yang quantum dynamics of solutes in a condensed phase is proposed to calculate linear and nonlinear vibrational rate are derived in Appendix A. The vibrational energy relaxation VER rate is negligible for slow

Cao, Jianshu

28

A Miniature Coupled Bistable Vibration Energy Harvester

NASA Astrophysics Data System (ADS)

This paper reports the design and test of a miniature coupled bistable vibration energy harvester. Operation of a bistable structure largely depends on vibration amplitude rather than frequency, which makes it very promising for wideband vibration energy harvesting applications. A coupled bistable structure consists of a pair of mobile magnets that create two potential wells and thus the bistable phenomenon. It requires lower excitation to trigger bistable operation compared to conventional bistable structures. Based on previous research, this work focused on miniaturisation of the coupled bistable structure for energy harvesting application. The proposed bistable energy harvester is a combination of a Duffing's nonlinear structure and a linear assisting resonator. Experimental results show that the output spectrum of the miniature coupled bistable vibration energy harvester was the superposition of several spectra. It had a higher maximum output power and a much greater bandwidth compared to simply the Duffing's structure without the assisting resonator.

Zhu, D.; Arthur, D. C.; Beeby, S. P.

2014-11-01

29

An electromagnetic, vibration-powered generator for intelligent sensor systems

This paper describes the design of miniature generators capable of converting ambient vibration energy into electrical energy for use in powering intelligent sensor systems. Such a device acts as the power supply of a microsystem which can be used in inaccessible areas where wires can not be practically attached to provide power or transmit sensor data. Two prototypes of miniature

P. Glynne-Jones; M. J. Tudor; S. P. Beeby; N. M. White

2004-01-01

30

Piezoelectric Power Scavenging of Mechanical Vibration and R H Middleton

Piezoelectric Power Scavenging of Mechanical Vibration Energy U K Singh 1 and R H Middleton 2 of the model, prototype of the power scavenging circuit, experimental results and its future perspectives motivating factor of this project. GENERAL POWER SCAVENGING The following are several common energy

Duffy, Ken

31

Vibration-to-electric energy conversion

A system is proposed to convert ambient mechanical vibration into electrical energy for use in powering autonomous low-power electronic systems. The energy is transduced through the use of a variable capacitor, which has been designed with MEMS (microelectromechanical systems) tech- nology. A low-power controller IC has been fabricated in a 0 6µm CMOS pro- cess and has been tested and

Scott Meninger; Jose Oscar Mur-Miranda; Rajeevan Amirtharajah; Anantha Chandrakasan; Jeffrey Lang

1999-01-01

32

Fault indications in MV-3B vibrator power supply

In accordance with standard requirements in hydroelectric power plants, the vibration conditions of electric generators is regularly inspected. A vibration sensor is described for field measurement of the generator vibration. The performance of the vibration testing unit is discussed.

Markovskii, Yu.G.; Minaev, E.K.; Polyakov, V.I.; Sychev, V.I.

1983-01-01

33

Scaling of electromagnetic vibration energy harvesting devices

NASA Astrophysics Data System (ADS)

A review of the vibration energy harvesting literature has been undertaken with the goal of establishing scaling laws for experimentally demonstrated harvesting devices. In particular electromagnetic harvesting devices are investigated. Power density metrics are examined with respect to scaling length, mass, frequency and drive acceleration. Improvements in demonstrated power density of harvesting devices over the past decade are noted. Scaling laws are observed that appear to suggest an upper limit to the power density achievable with current harvesting techniques.

Moss, Scott D.; Payne, Owen R.; Hart, Genevieve A.

2014-04-01

34

A vibration energy harvester using magnet/piezoelectric composite transducer

NASA Astrophysics Data System (ADS)

In this research, a vibration energy harvester employing the magnet/piezoelectric composite transducer to convert mechanical vibration energy into electrical energy is presented. The electric output performance of a vibration energy harvester has been investigated. Compared to traditional magnetoelectric transducer, the proposed vibration energy harvester has some remarkable characteristic which do not need binder. The experimental results show that the presented vibration energy harvester can obtain an average power of 0.39 mW for an acceleration of 0.6g at frequency of 38 Hz. Remarkably, this power is a very encouraging power figure that gives the prospect of being able to power a widely range of wireless sensors in wireless sensor network.

Qiu, Jing; Chen, Hengjia; Wen, Yumei; Li, Ping; Yang, Jin; Li, Wenli

2014-05-01

35

Self-powered signal processing using vibration-based power generation

Low power design trends raise the possibility of using ambient energy to power future digital systems. A chip has been designed and tested to demonstrate the feasibility of operating a digital system from power generated by vibrations in its environment. A moving coil electromagnetic transducer was used as a power generator. Calculations show that power on the order of 400

Rajeevan Amirtharajah; Anantha P. Chandrakasan

1998-01-01

36

Vibrational power flow analysis of rods and beams. Thesis

NASA Technical Reports Server (NTRS)

A new method to model vibrational power flow and predict the resulting energy density levels in uniform rods and beams is investigated. This method models the flow of vibrational power in a manner analogous to the flow of thermal power in a heat conduction problem. The classical displacement solutions for harmonically excited, hysteretically damped rods and beams are used to derive expressions for the vibrational power flow and energy density in the rod and beam. Under certain conditions, the power flow in these two structural elements will be shown to be proportional to the energy density gradient. Using the relationship between power flow and energy density, an energy balance on differential control volumes in the rod and beam leads to a Poisson's equation which models the energy density distribution in the rod and beam. Coupling the energy density and power flow solutions for rods and beams is also discussed. It is shown that the resonant behavior of finite structures complicates the coupling of solutions, especially when the excitations are single frequency inputs. Two coupling formulations are discussed, the first based on the receptance method, and the second on the travelling wave approach used in Statistical Energy Analysis. The receptance method is the more computationally intensive but is capable of analyzing single frequency excitation cases. The traveling wave approach gives a good approximation of the frequency average of energy density and power flow in coupled systems, and thus, is an efficient technique for use with broadband frequency excitation.

Wohlever, James Christopher; Bernhard, R. J.

1988-01-01

37

Harvesting Vibrational Energy Using Material Work Functions

NASA Astrophysics Data System (ADS)

Vibration energy harvesters scavenge energy from mechanical vibrations to energise low power electronic devices. In this work, we report on vibration energy harvesting scheme based on the charging phenomenon occurring naturally between two bodies with different work functions. Such work function energy harvester (WFEH) is similar to electrostatic energy harvester with the fundamental distinction that neither external power supplies nor electrets are needed. A theoretical model and description of different operation modes of WFEHs are presented. The WFEH concept is tested with macroscopic experiments, which agree well with the model. The feasibility of miniaturizing WFEHs is shown by simulating a realistic MEMS device. The WFEH can be operated as a charge pump that pushes charge and energy into an energy storage element. We show that such an operation mode is highly desirable for applications and that it can be realised with either a charge shuttle or with switches. The WFEH is shown to give equal or better output power in comparison to traditional electrostatic harvesters. Our findings indicate that WFEH has great potential in energy harvesting applications.

Varpula, Aapo; Laakso, Sampo J.; Havia, Tahvo; Kyynäräinen, Jukka; Prunnila, Mika

2014-10-01

38

Harvesting vibrational energy using material work functions.

Vibration energy harvesters scavenge energy from mechanical vibrations to energise low power electronic devices. In this work, we report on vibration energy harvesting scheme based on the charging phenomenon occurring naturally between two bodies with different work functions. Such work function energy harvester (WFEH) is similar to electrostatic energy harvester with the fundamental distinction that neither external power supplies nor electrets are needed. A theoretical model and description of different operation modes of WFEHs are presented. The WFEH concept is tested with macroscopic experiments, which agree well with the model. The feasibility of miniaturizing WFEHs is shown by simulating a realistic MEMS device. The WFEH can be operated as a charge pump that pushes charge and energy into an energy storage element. We show that such an operation mode is highly desirable for applications and that it can be realised with either a charge shuttle or with switches. The WFEH is shown to give equal or better output power in comparison to traditional electrostatic harvesters. Our findings indicate that WFEH has great potential in energy harvesting applications. PMID:25348004

Varpula, Aapo; Laakso, Sampo J; Havia, Tahvo; Kyynäräinen, Jukka; Prunnila, Mika

2014-01-01

39

Energy harvesting from wind-induced vibration of suspension bridges

Recently, an extensive amount of research has been focused on energy harvesting from structural vibration sources for wireless self-powered microsystem applications. One method of energy harvesting is using electromagnetic ...

Shi, Miao, M. Eng. Massachusetts Institute of Technology

2013-01-01

40

Wideband Piezomagnetoelastic Vibration Energy Harvesting

NASA Astrophysics Data System (ADS)

This work presents a small-scale wideband piezomagnetoelastic vibration energy harvester (VEH) aimed for operation at frequencies of a few hundred Hz. The VEH consists of a tape-casted PZT cantilever with thin sheets of iron foil attached on each side of the free tip. The wideband operation is achieved by placing the cantilever in a magnetic field induced by either one or two magnets located oppositely of the cantilever. The attraction force created by the magnetic field and iron foils introduces a mechanical force in opposite direction of the cantilevers restoring force causing a spring softening effect. In linear operation (without magnets) the harvester generates a RMS power of 141 ?W/g2 at 588 Hz with a relative bandwidth of 3.8% over a 100 k? load resistor. When operated with one magnet ideally positioned opposite the cantilever, a RMS power of 265 ?W/g2 is generated at 270 Hz with a relative bandwidth of 25%.

Lei, Anders; Thomsen, Erik V.

2014-11-01

41

Adaptive learning algorithms for vibration energy harvesting

NASA Astrophysics Data System (ADS)

By scavenging energy from their local environment, portable electronic devices such as MEMS devices, mobile phones, radios and wireless sensors can achieve greater run times with potentially lower weight. Vibration energy harvesting is one such approach where energy from parasitic vibrations can be converted into electrical energy through the use of piezoelectric and electromagnetic transducers. Parasitic vibrations come from a range of sources such as human movement, wind, seismic forces and traffic. Existing approaches to vibration energy harvesting typically utilize a rectifier circuit, which is tuned to the resonant frequency of the harvesting structure and the dominant frequency of vibration. We have developed a novel approach to vibration energy harvesting, including adaptation to non-periodic vibrations so as to extract the maximum amount of vibration energy available. Experimental results of an experimental apparatus using an off-the-shelf transducer (i.e. speaker coil) show mechanical vibration to electrical energy conversion efficiencies of 27-34%.

Ward, John K.; Behrens, Sam

2008-06-01

42

Adaptive learning algorithms for vibration energy harvesting

By scavenging energy from their local environment, portable electronic devices such as MEMS devices, mobile phones, radios and wireless sensors can achieve greater run times with potentially lower weight. Vibration energy harvesting is one such approach where energy from parasitic vibrations can be converted into electrical energy through the use of piezoelectric and electromagnetic transducers. Parasitic vibrations come from a

John K. Ward; Sam Behrens

2008-01-01

43

A MEMS vibration energy harvester for automotive applications

NASA Astrophysics Data System (ADS)

The objective of this work is to develop MEMS vibration energy harvesters for tire pressure monitoring systems (TPMS), they can be located on the rim or on the inner-liner of the car tire. Nowadays TPMS modules are powered by batteries with a limited lifetime. A large effort is ongoing to replace batteries with small and long lasting power sources like energy harvesters [1]. The operation principle of vibration harvesters is mechanical resonance of a seismic mass, where mechanical energy is converted into electrical energy. In general, vibration energy harvesters are of specific interest for machine environments where random noise or repetitive shock vibrations are present. In this work we present the results for MEMS based vibration energy harvesting for applying on the rim or inner-liner. The vibrations on the rim correspond to random noise. A vibration energy harvester can be described as an under damped mass-spring system acting like a mechanical band-pass filter, and will resonate at its natural frequency [2]. At 0.01 g2/Hz noise amplitude the average power can reach the level that is required to power a simple wireless sensor node, approximately 10 ?W [3]. The dominant vibrations on the inner-liner consist mainly of repetitive high amplitude shocks. With a shock, the seismic mass is displaced, after which the mass will "ring-down" at its natural resonance frequency. During the ring-down period, part of the mechanical energy is harvested. On the inner-liner of the tire repetitive (one per rotation) high amplitude (few hundred g) shocks occur. The harvester enables an average power of a few tens of ?W [4], sufficient to power a more sophisticated wireless sensor node that can measure additional tire-parameters besides pressure. In this work we characterized MEMS vibration energy harvesters for noise and shock excitation. We validated their potential for TPMS modules by measurements and simulation.

van Schaijk, R.; Elfrink, R.; Oudenhoven, J.; Pop, V.; Wang, Z.; Renaud, M.

2013-05-01

44

Electrostatic vibration-to-electric energy conversion

Ultra-Low-Power electronics can perform useful functions with power levels as low as 170 nW. This makes them amenable to powering from ambient sources such as vibration. In this case, they can become autonomous. Motivated ...

Mur Miranda, José Oscar, 1972-

2004-01-01

45

Vibrational energy transfer in fluids

NASA Astrophysics Data System (ADS)

A review of several of the available theories of vibrational energy transfer (VET) in the gas and liquid phases is presented. First the classical theory of gas phase VET mainly due to Landau and Teller, to Jackson and Mott and to Zener is developed in some detail. Next the Schwartz-Slawsky-Herzfeld theory, a framework for analysing VET data based on the classical theory, is outlined. Experimental tests of the classical theory and theoretical critiques of its assumptions are then described. Next a brief review of the modern ab-initio quantum approach to gas phase VET rates, taking as an example the work of Banks, Clary and Werner, is given. Theories of VET at elevated densities are then discussed. The isolated binary collision model is reviewed and a new molecular approach to the density, temperature and isotope dependences of vibrational energy relaxation rates, due to Adelman and co-workers, is outlined.

Miller, David W.; Adelman, Steven A.

46

Demonstration of Energy-Neutral Operation on a WSN Testbed Using Vibration Energy Harvesting

for harvesting are generally from radio-frequency (RF) power conversion, solar energy conversion and vibration-to-electrical energy conversion The RF harvester is used in [7] to increase primary battery lifetime of the ultraDemonstration of Energy-Neutral Operation on a WSN Testbed Using Vibration Energy Harvesting S

Uysal-Biyikoglu, Elif

47

Similarity and duality of electromagnetic and piezoelectric vibration energy harvesters

NASA Astrophysics Data System (ADS)

A frequency analysis has been conducted to study vibration energy harvesting performance and characteristics of a single degree of freedom vibration energy harvester connected to a single load resistor based on the Laplace transfer method and physical models of a voltage source. The performance and characteristics of electromagnetic and piezoelectric harvesters have been analysed and compared. The main research outcome is the disclosure of similarity and duality of electromagnetic and piezoelectric harvesters for both the energy harvesting efficiency and the normalised resonant harvested power using only two dimensionless characteristic parameters: the normalised resistance and the normalised force factor. The dimensionless resonant harvested power and energy harvesting efficiency analysis allows for a parameter study and optimization of the ambient vibration energy harvesters from macro- to nano-scales and for evaluation of the vibration energy harvester performance regardless of the size and type.

Wang, Xu; John, Sabu; Watkins, Simon; Yu, Xinghuo; Xiao, Han; Liang, Xingyu; Wei, Haiqiao

2015-02-01

48

Evaluating vehicular-induced bridge vibrations for energy harvesting applications

NASA Astrophysics Data System (ADS)

Highway bridges are vital links in the transportation network in the United States. Identifying possible safety problems in the approximately 600,000 bridges across the country is generally accomplished through labor-intensive, visual inspections. Ongoing research sponsored by NIST seeks to improve inspection practices by providing real-time, continuous monitoring technology for steel bridges. A wireless sensor network with a service life of ten years that is powered by an integrated energy harvester is targeted. In order to achieve the target ten-year life for the monitoring system, novel approaches to energy harvesting for use in recharging batteries are investigated. Three main sources of energy are evaluated: (a) vibrational energy, (b) solar energy, and (c) wind energy. Assessing the energy produced from vehicular-induced vibrations and converted through electromagnetic induction is the focus of this paper. The goal of the study is to process acceleration data and analyze the vibrational response of steel bridges to moving truck loads. Through spectral analysis and harvester modeling, the feasibility of vibration-based energy harvesting for longterm monitoring can be assessed. The effects of bridge conditions, ambient temperature, truck traffic patterns, and harvester position on the power content of the vibrations are investigated. With sensor nodes continually recharged, the proposed real-time monitoring system will operate off the power grid, thus reducing life cycle costs and enhancing inspection practices for state DOTs. This paper will present the results of estimating the vibration energy of a steel bridge in Texas.

Reichenbach, Matthew; Fasl, Jeremiah; Samaras, Vasilis A.; Wood, Sharon; Helwig, Todd; Lindenberg, Richard

2012-04-01

49

A POWER FLOW METHOD FOR EVALUATING VIBRATION FROM UNDERGROUND RAILWAYS

A POWER FLOW METHOD FOR EVALUATING VIBRATION FROM UNDERGROUND RAILWAYS M.F.M. Hussein, H.E.M. Hunt of ground-borne vibration is the running of trains in underground railway tunnels. Vibration is generated, which can be used with any underground-tunnel model. To evaluate the effect of vibration countermeasures

Talbot, James P.

50

Vibration energy harvesting from random force and motion excitations

NASA Astrophysics Data System (ADS)

A vibration energy harvester is typically composed of a spring-mass system with an electromagnetic or piezoelectric transducer connected in parallel with a spring. This configuration has been well studied and optimized for harmonic vibration sources. Recently, a dual-mass harvester, where two masses are connected in series by the energy transducer and a spring, has been proposed. The dual-mass vibration energy harvester is proved to be able to harvest more power and has a broader bandwidth than the single-mass configuration, when the parameters are optimized and the excitation is harmonic. In fact, some dual-mass vibration energy harvesters, such as regenerative vehicle suspensions and buildings with regenerative tuned mass dampers (TMDs), are subjected to random excitations. This paper is to investigate the dual-mass and single-mass vibration harvesters under random excitations using spectrum integration and the residue theorem. The output powers for these two types of vibration energy harvesters, when subjected to different random excitations, namely force, displacement, velocity and acceleration, are obtained analytically with closed-form expressions. It is also very interesting to find that the output power of the vibration energy harvesters under random excitations depends on only a few parameters in very simple and elegant forms. This paper also draws some important conclusions on regenerative vehicle suspensions and buildings with regenerative TMDs, which can be modeled as dual-mass vibration energy harvesters. It is found that, under white-noise random velocity excitation from road irregularity, the harvesting power from vehicle suspensions is proportional to the tire stiffness and road vertical excitation spectrum only. It is independent of the chassis mass, tire-wheel mass, suspension stiffness and damping coefficient. Under random wind force excitation, the power harvested from buildings with regenerative TMD will depends on the building mass only, not on the parameters of the TMD subsystem if the ratio of electrical and mechanical damping is constant.

Tang, Xiudong; Zuo, Lei

2012-07-01

51

A comparison between several vibration-powered piezoelectric generators for standalone systems

This paper presents a comparison between four vibration-powered generators designed to power standalone systems, such as wireless transducers. Ambient vibrations are converted into electrical energy using piezoelectric materials. The originality of the proposed approaches is based on a particular processing of the voltage delivered by the piezoelectric material, which enhances the electromechanical conversion. The principle of each processing circuit is

E. Lefeuvre; A. Badel; C. Richard; L. Petit; D. Guyomar

2006-01-01

52

Piezoelectric Power Requirements for Active Vibration Control

NASA Technical Reports Server (NTRS)

This paper presents a method for predicting the power consumption of piezoelectric actuators utilized for active vibration control. Analytical developments and experimental tests show that the maximum power required to control a structure using surface-bonded piezoelectric actuators is independent of the dynamics between the piezoelectric actuator and the host structure. The results demonstrate that for a perfectly-controlled system, the power consumption is a function of the quantity and type of piezoelectric actuators and the voltage and frequency of the control law output signal. Furthermore, as control effectiveness decreases, the power consumption of the piezoelectric actuators decreases. In addition, experimental results revealed a non-linear behavior in the material properties of piezoelectric actuators. The material non- linearity displayed a significant increase in capacitance with an increase in excitation voltage. Tests show that if the non-linearity of the capacitance was accounted for, a conservative estimate of the power can easily be determined.

Brennan, Matthew C.; McGowan, Anna-Maria Rivas

1997-01-01

53

A study of low level vibrations as a power source for wireless sensor nodes

Advances in low power VLSI design, along with the potentially low duty cycle of wireless sensor nodes open up the possibility of powering small wireless computing devices from scavenged ambient power. A broad review of potential power scavenging technologies and conventional energy sources is first presented. Low-level vibrations occurring in common household and office environments as a potential power source

Shad Roundy; Paul K. Wright; Jan M. Rabaey

2003-01-01

54

NASA Technical Reports Server (NTRS)

Stirling Technology Company (STC), as part of a Small Business Innovation Research contract Phase II with the NASA Glenn Research Center at Lewis Field, is developing an Adaptive Vibration Reduction System (AVRS) that will effectively eliminate vibrations for the Stirling radioisotope power system. The AVRS will reduce vibration levels for two synchronized, opposed Stirling converters by a factor of 10 or more under normal operating conditions. Even more importantly, the AVRS will be adaptive and will be able to adjust to any changing converter conditions over the course of a mission. The Stirling converter is being developed by NASA and the Department of Energy (DOE) as a high-efficiency option for a radioisotope power system to provide onboard electric power for NASA deep space missions. The high Stirling efficiency of over 25 percent for this application will reduce the required amount of isotope by more than a factor of 3 in comparison to the current radioisotope thermoelectric generators (RTG s). Stirling is the most developed converter option of the advanced power technologies under consideration.

Thieme, Lanny G.

2000-01-01

55

An electromagnetic micro power generator for wideband environmental vibrations

This paper presents a wideband electromagnetic vibration-to-electrical micro power generator. The micro generator is capable of generating steady power over a predetermined frequency range. Power is generated by means of the relative motion between a magnet and coils fabricated over resonating cantilevers through electromagnetic induction. The reported generator covers a wide band of external vibration frequency by implementing a number

Ibrahim Sari; Tuna Balkan; Haluk Kulah

2008-01-01

56

Noise powered nonlinear energy harvesting

NASA Astrophysics Data System (ADS)

The powering of small-scale electronic mobile devices has been in recent years the subject of a great number of research efforts aimed primarily at finding an alternative solution to standard batteries. The harvesting of kinetic energy present in the form of random vibrations (from non-equilibrium thermal noise up to machine vibrations) is an interesting option due to the almost universal presence of some kind of motion. Present working solutions for vibration energy harvesting are based on oscillating mechanical elements that convert kinetic energy via capacitive, inductive or piezoelectric methods. These oscillators are usually designed to be resonantly tuned to the ambient dominant frequency. However, in most cases the ambient random vibrations have their energy distributed over a wide spectrum of frequencies, especially at low frequency, and frequency tuning is not always possible due to geometrical/dynamical constraints. We present a new approach to the powering of small autonomous sensors based on vibration energy harvesting by the exploitation of nonlinear stochastic dynamics. Such a method is shown to outperform standard linear approaches based on the use of resonant oscillators and to overcome some of the most severe limitations of present strategies, like narrow bandwidth, need for continuous frequency tuning and low power efficiency. We demonstrate the superior performances of this method by applying it to piezoelectric energy harvesting from ambient vibration.

Gammaitoni, Luca; Neri, Igor; Vocca, Helios

2011-04-01

57

Calculated rotation-vibration energies for HOC +

NASA Astrophysics Data System (ADS)

We use the ab initio potential surfaces discussed in the immediately preceding paper, with the nonrigid bender Hamiltonian, to calculate rotation-vibration energies for the ground electronic state of HOC +. The results obtained agree with the currently available experimental rotational energy level separations in four HOC + isotopes to within 0.03%. The predicted rotation-vibration energy separations should be of assistance in the experimental search for the corresponding transitions.

Bunker, P. R.; Jensen, Per; Kraemer, W. P.; Beardsworth, R.

1987-02-01

58

Calculated rotation-vibration energies for HOC+

We use the ab initio potential surfaces discussed in the immediately preceding paper, with the nonrigid bender Hamiltonian, to calculate rotation-vibration energies for the ground electronic state of HOC+. The results obtained agree with the currently available experimental rotational energy level separations in four HOC+ isotopes to within 0.03%. The predicted rotation-vibration energy separations should be of assistance in the

P. R. Bunker; Per Jensen; W. P. Kraemer; R. Beardsworth

1987-01-01

59

On Kinetics Modeling of Vibrational Energy Transfer

NASA Technical Reports Server (NTRS)

Two models of vibrational energy exchange are compared at equilibrium to the elementary vibrational exchange reaction for a binary mixture. The first model, non-linear in the species vibrational energies, was derived by Schwartz, Slawsky, and Herzfeld (SSH) by considering the detailed kinetics of vibrational energy levels. This model recovers the result demanded at equilibrium by the elementary reaction. The second model is more recent, and is gaining use in certain areas of computational fluid dynamics. This model, linear in the species vibrational energies, is shown not to recover the required equilibrium result. Further, this more recent model is inconsistent with its suggested rate constants in that those rate constants were inferred from measurements by using the SSH model to reduce the data. The non-linear versus linear nature of these two models can lead to significant differences in vibrational energy coupling. Use of the contemporary model may lead to significant misconceptions, especially when integrated in computer codes considering multiple energy coupling mechanisms.

Gilmore, John O.; Sharma, Surendra P.; Cavolowsky, John A. (Technical Monitor)

1996-01-01

60

The effects of collision energy, vibrational mode, and vibrational angular momentum on energy effects of NO2 + vibrational excitation that extend over the entire collision energy range, implying dynamics trajectories for NO2 + +Kr reproduce both the collision energy and vibrational state effects

Anderson, Scott L.

61

Abstract--This paper presents ambient mechanical vibrations as an alternative source for energy harvesting, especially beneficial where alternatives such as light, wind, biomass and thermal energy are limited, e.g., powering underground sensors. Transduction of ambient kinetic energy, e.g., the vibrations

Kumar, Ratnesh

62

Vibration power generator for a linear MR damper

NASA Astrophysics Data System (ADS)

The paper describes the structure and the results of numerical calculations and experimental tests of a newly developed vibration power generator for a linear magnetorheological (MR) damper. The generator consists of permanent magnets and coil with foil winding. The device produces electrical energy according to Faraday's law of electromagnetic induction. This energy is applied to vary the damping characteristics of the MR damper attached to the generator by the input current produced by the device. The objective of the numerical calculations was to determine the magnetic field distribution in the generator as well as the electric potential and current density in the generator's coil during the idle run and under the load applied to the MR damper control coil. The results of the calculations were used during the design and manufacturing stages of the device. The objective of the experimental tests carried out on a dynamic testing machine was to evaluate the generator's efficiency and to compare the experimental and predicted data. The experimental results demonstrate that the engineered device enables a change in the kinetic energy of the reciprocal motion of the MR damper which leads to variations in the damping characteristics. That is why the generator may be used to build up MR damper based vibration control systems which require no external power.

Sapi?ski, Bogdan

2010-10-01

63

The vibrational energy pattern acetylene ''VI...: Inter and intrapolyad structures

The vibrational energy pattern acetylene ''VI...: InterÂ and intrapolyad structures B. I. Zhilinski March 2000; accepted August 2000# IntraÂ interpolyad structures are investigated vibrational energy of vibrational energy levels. Distinct regular oscillatory contributions evidenced number vibrational levels main

ZhilinskiÃ, Boris

64

Power hand tool vibration effects on grip exertions

Operation of vibrating power hand tools can result in excessive grip force, which may increase the risk of cumulative trauma disorders in the upper extremities. An experiment was performed to study grip force exerted by 14 subjects operating a simulated hand tool vibrating at 9.8 m\\/s and 49 m\\/s acceleration magnitudes, at 40 Hz and 160 Hz frequencies, with vibration

ROBERT G. RADWIN; THOMAS J. ARMSTRONG; DON B. CHAFFIN

1987-01-01

65

Converged vibrational energy levels and quantum mechanical vibrational partition function of ethane

Converged vibrational energy levels and quantum mechanical vibrational partition function of ethane-0431 Received 25 January 2006; accepted 15 March 2006; published online 9 May 2006 The vibrational partition that were calculated by vibrational configuration interaction, and the results are compared to the harmonic

Truhlar, Donald G

66

Formal journal article Experimental analysis of a piezoelectric energy harvesting system for harmonic, random, and sine on random vibration Abstract: Harvesting power with a piezoelectric vibration powered generator using a full-wave rectifier conditioning circuit is experimentally compared for varying sinusoidal, random and sine on random (SOR) input vibration scenarios. Additionally, the implications of source vibration characteristics on harvester design are discussed. Studies in vibration harvesting have yielded numerous alternatives for harvesting electrical energy from vibrations but piezoceramics arose as the most compact, energy dense means of energy transduction. The rise in popularity of harvesting energy from ambient vibrations has made piezoelectric generators commercially available. Much of the available literature focuses on maximizing harvested power through nonlinear processing circuits that require accurate knowledge of generator internal mechanical and electrical characteristics and idealization of the input vibration source, which cannot be assumed in general application. In this manuscript, variations in source vibration and load resistance are explored for a commercially available piezoelectric generator. We characterize the source vibration by its acceleration response for repeatability and transcription to general application. The results agree with numerical and theoretical predictions for in previous literature that load optimal resistance varies with transducer natural frequency and source type, and the findings demonstrate that significant gains are seen with lower tuned transducer natural frequencies for similar source amplitudes. Going beyond idealized steady state sinusoidal and simplified random vibration input, SOR testing allows for more accurate representation of real world ambient vibration. It is shown that characteristic interactions from more complex vibrational sources significantly alter power generation and power processing requirements by increasing harvested power, shifting optimal conditioning impedance, inducing significant voltage supply fluctuations and ultimately rendering idealized sinusoidal and random analyses insufficient.

Cryns, Jackson W.; Hatchell, Brian K.; Santiago-Rojas, Emiliano; Silvers, Kurt L.

2013-07-01

67

Piezoelectric energy harvesting from traffic-induced bridge vibrations

NASA Astrophysics Data System (ADS)

This paper focuses on energy harvesting from traffic-induced vibrations in bridges. Using a pre-stressed concrete highway bridge as a case study, in situ vibration measurements are presented and analysed. From these results, a prototype of a cantilever piezoelectric harvester is designed, tested and modelled. Even though the considered bridge vibrations are characterized by small amplitude and a low frequency (i.e. below 15 Hz), it is shown that mean power of the order of 0.03 mW can be produced, with a controlled voltage between 1.8 and 3.6 V. A simple model is proposed for theoretical prediction of the delivered power in terms of traffic intensity. This model shows good agreement with the experimental results and leads to a simple but effective design rule for piezoelectric harvesters to be used on bridges.

Peigney, Michaël; Siegert, Dominique

2013-09-01

68

Vibrational Power Flow in the Moving Belt Passing Through a Tensioner

NASA Astrophysics Data System (ADS)

Because of the high performance and low weight requirements for modern machines including engines, the belts servicing high dynamic loads at high speed tend to be very susceptible to the transferred vibration. In this paper, a method is proposed for obtaining the physical characteristics of the transverse vibrational power flow through moving rubber belts. The governing equation is derived by applying Hamilton's principle to the description of the flexural vibrations in axially moving belts, where the tensioner is considered to be a one-degree-of-freedom system. The total power flow calculated and measured in the moving belt is the sum of the true power flow and the power component associated with the steady medium motion. Consequently, any component that is due solely to the belt movement should be subtracted from the total power flow in order to obtain the true, net power flow. This concept is employed in calculating the transverse vibrational power flow through belt-pulley systems that include a tensioner. An equivalent system including an idler instead of the tensioner is also considered, and the observed power flow in this condition is ascribed to the power flow due only to the movement of the medium. The results of analysis show that the vibrational power of the two belt-spans flows into the tensioner. It is shown that the energy flow, measured by using two laser sensors, agrees reasonably well with the predicted results.

KWON, Y. I.; IH, J.-G.

2000-01-01

69

Harvesting vibration energy by a triple-cantilever based triboelectric nanogenerator

University Press and Springer-Verlag Berlin Heidelberg 2013 KEYWORDS triboelectric nanogenerator, harvestingHarvesting vibration energy by a triple-cantilever based triboelectric nanogenerator Weiqing Yang1 vibration energy, triple-cantilever, self-powered systems ABSTRACT Triboelectric nanogenerators (TENG

Wang, Zhong L.

70

INCREASED-BANDWIDTH, MEANDERING VIBRATION ENERGY HARVESTER D. F. Berdy1,3

in a low-frequency, meandering piezoelectric vibration energy harvester. The fabricated device features twoINCREASED-BANDWIDTH, MEANDERING VIBRATION ENERGY HARVESTER D. F. Berdy1,3 , B. Jung1 , J. F. Rhoads, piezoelectric, distributed mass, meander INTRODUCTION Decreasing power requirements and an increasing need

Rhoads, Jeffrey F.

71

Damping and energy dissipation in soft tissue vibrations during running.

It has been well accepted that the vibrations of soft tissue cannot be simulated by a single sinusoidal function. In fact, these vibrations are a combination of several vibration modes. In this study, these modes are extracted applying a recently developed method namely, partly ensemble empirical mode decomposition (PEEMD). Then, a methodology for estimating the damping properties and energy dissipation caused by damping for each mode is used. Applying this methodology on simulated signals demonstrates high accuracy. This methodology is applied to the acceleration signals of the gastrocnemius muscle during sprinting and the differences between the damping properties of different vibration modes were identified. The results were 1) the damping property of high-frequency mode was higher than that for low-frequency modes. 2) All identified modes were in under damped condition, therefore, the vibrations had an oscillatory nature. 3) The damping ratios of lower modes are about 100% increased compared to higher modes. 4) The energy dissipation occurred in lower modes were much more than that for higher mode; According to the power spectrum of the ground reaction force (GRF), which is the input force into the body, the recent finding supports the muscle tuning paradigm. It is suggested that the damping properties and energy dissipation can be used to distinguish between different running conditions (surface, fatigue, etc.). PMID:25527887

Khassetarash, Arash; Hassannejad, Reza; Enders, Hendrik; Ettefagh, Mir Mohammad

2015-01-21

72

Estimating Vibrational Powers Of Parts In Fluid Machinery

NASA Technical Reports Server (NTRS)

In new method of estimating vibrational power associated with component of fluid-machinery system, physics of flow through (or in vicinity of) component regarded as governing vibrations. Devised to generate scaling estimates for design of new parts of rocket engines (e.g., pumps, combustors, nozzles) but applicable to terrestrial pumps, turbines, and other machinery in which turbulent flows and vibrations caused by such flows are significant. Validity of method depends on assumption that fluid flows quasi-steadily and that flow gives rise to uncorrelated acoustic powers in different parts of pump.

Harvey, S. A.; Kwok, L. C.

1995-01-01

73

Mechanical vibration to electrical energy converter

Electromechanical devices that generate an electrical signal in response to an external source of mechanical vibrations can operate as a sensor of vibrations and as an energy harvester for converting mechanical vibration to electrical energy. The devices incorporate a magnet that is movable through a gap in a ferromagnetic circuit, wherein a coil is wound around a portion of the ferromagnetic circuit. A flexible coupling is used to attach the magnet to a frame for providing alignment of the magnet as it moves or oscillates through the gap in the ferromagnetic circuit. The motion of the magnet can be constrained to occur within a substantially linear range of magnetostatic force that develops due to the motion of the magnet. The devices can have ferromagnetic circuits with multiple arms, an array of magnets having alternating polarity and, encompass micro-electromechanical (MEM) devices.

Kellogg, Rick Allen (Tijeras, NM); Brotz, Jay Kristoffer (Albuquerque, NM)

2009-03-03

74

Unidirectional vibrational energy flow in nitrobenzene.

Experiments were performed on nitrobenzene liquid at ambient temperature to probe vibrational energy flow from the nitro group to the phenyl group and vice versa. The IR pump, Raman probe method was used. Quantum chemical calculations were used to sort the normal modes of nitrobenzene into three categories: phenyl modes, nitro modes, and global modes. IR wavelengths in the 2500-3500 cm(-1) range were found that best produced excitations initially localized on nitro or phenyl. Pulses at 2880 cm(-1) excited a nitro stretch combination band. Pulses at 3080 cm(-1) excited a phenyl C-H stretch plus some nitro stretch. With nitro excitation there was no detectable energy transfer to phenyl. With phenyl excitation there was no direct transfer to nitro, but there was some transfer to global modes such as phenyl-nitro stretching, so some of the vibrational amplitude on phenyl moved onto nitro. Thus energy transfer from nitro to phenyl was absent, but there was weak energy transfer from phenyl to nitro. The experimental methods described here can be used to study vibrational energy flow from one part of a molecule to another, which could assist in the design of molecules for molecular electronics and phononics. The vibrational isolation of the nitro group when attached to a phenyl moiety suggests that strongly nonthermal reaction pathways may play an important role in impact initiation of energetic materials having peripheral nitro groups. PMID:23432106

Pein, Brandt C; Sun, Yuxiao; Dlott, Dana D

2013-07-25

75

Vibration energy harvesting by magnetostrictive material

A new class of vibration energy harvester based on magnetostrictive material (MsM), Metglas 2605SC, is designed, developed and tested. It contains two submodules: an MsM harvesting device and an energy harvesting circuit. Compared to piezoelectric materials, the Metglas 2605SC offers advantages including higher energy conversion efficiency, longer life cycles, lack of depolarization and higher flexibility to survive in strong ambient

Lei Wang; F. G. Yuan

2008-01-01

76

Vibrational energy transport in molecular wires

NASA Astrophysics Data System (ADS)

Motivated by recent experimental observation (see, e.g., I. V. Rubtsov, Acc. Chem. Res. 42, 1385 (2009)) of vibrational energy transport in (CH2O) N and (CF2) N molecular chains ( N = 4-12), in this paper we present and solve analytically a simple one dimensional model to describe theoretically these data. To mimic multiple conformations of the molecular chains, our model includes random off-diagonal couplings between neigh-boring sites. For the sake of simplicity, we assume Gaussian distribution with dispersion ? for these coupling matrix elements. Within the model we find that initially locally excited vibrational state can propagate along the chain. However, the propagation is neither ballistic nor diffusion like. The time T m for the first passage of the excitation along the chain, scales linearly with N in the agreement with the experimental data. Distribution of the excitation energies over the chain fragments (sites in the model) remains random, and the vibrational energy, transported to the chain end at t = T m is dramatically decreased when ? is larger than characteristic interlevel spacing in the chain vibrational spectrum. We do believe that the problem we have solved is not only of intellectual interest (or to rationalize mentioned above experimental data) but also of relevance to design optimal molecular wires providing fast energy transport in various chemical and biological reactions.

Benderskii, V. A.; Kotkin, A. S.; Rubtsov, I. V.; Kats, E. I.

2013-10-01

77

Efficiency enhancement of a cantilever-based vibration energy harvester.

Extracting energy from ambient vibration to power wireless sensor nodes has been an attractive area of research, particularly in the automotive monitoring field. This article reports the design, analysis and testing of a vibration energy harvesting device based on a miniature asymmetric air-spaced cantilever. The developed design offers high power density, and delivers electric power that is sufficient to support most wireless sensor nodes for structural health monitoring (SHM) applications. The optimized design underwent three evolutionary steps, starting from a simple cantilever design, going through an air-spaced cantilever, and ending up with an optimized air-spaced geometry with boosted power density level. Finite Element Analysis (FEA) was used as an initial tool to compare the three geometries' stiffness (K), output open-circuit voltage (V(ave)), and average normal strain in the piezoelectric transducer (?(ave)) that directly affect its output voltage. Experimental tests were also carried out in order to examine the energy harvesting level in each of the three designs. The experimental results show how to boost the power output level in a thin air-spaced cantilever beam for energy within the same space envelope. The developed thin air-spaced cantilever (8.37 cm3), has a maximum power output of 2.05 mW (H = 29.29 ?J/cycle). PMID:24366177

Kubba, Ali E; Jiang, Kyle

2013-01-01

78

Model reduction in stochastic vibration energy harvesting using compressive sampling

NASA Astrophysics Data System (ADS)

Vibration energy harvesters are designed to gather parasitic energy from the motion of their host structures. In many germane scenarios, this motion is broadband; however, the preponderance of design criteria appearing in the literature for vibration energy harvesters considers sinusoidal base excitation at a single frequency. While this analysis often leads to analytical formulas for estimating power harvested, they fail to account for the contribution of multiple frequency components of the host motion and the excitation of higher vibration modes of the transducer. In this paper, an attempt is made to provide brief, analytical approximation of these additional factors. To wit, the single-mode, single-frequency power formula is extended to multi-frequency inputs and multiple modal excitations by matching each base acceleration frequency component to at most one mode of vibration whose half-power bandwidth that frequency falls within. Then, due to orthogonality, the expected power can be written as the sum of the contributions of the individual frequency components. To demonstrate the accuracy of this approximation, recorded acceleration signals from a car idling and a person walking are used as inputs, and predictions from the approximation are compared to results from full simulations. Approximations using only three frequency components are shown to be more than 80% accurate, with increased accuracy as the base acceleration signal becomes narrower in bandwidth. The effects of charge cancellation in the higher modes are also considered using simulations and the aforementioned approximations. These studies show that rectifying the strain in the higher modes is only beneficial if these modes contribute significantly to the power harvested. The approximate formulas derived in this paper are useful for making this determination.

Wickenheiser, A. M.

2013-09-01

79

Multi-link piezoelectric structure for vibration energy harvesting

NASA Astrophysics Data System (ADS)

Work in piezoelectric vibration energy harvesting has typically focused on single member cantilevered structures with transverse tip displacement at a known frequency, taking advantage of the optimal coupling characteristics of piezoceramics in the 3-1 bending mode. Multi-member designs could be advantageous in delivering power to a load in environments with random or wide-band vibrations. The design presented in this work consists of two hinged piezoceramic (PZT-5A) beams x-poled for series operation. Each beam measures 31.8mm x 12.7mm x 0.38mm and consists of two layers of nickel-plated piezoceramic adhered to a brass center shim. The hinge device consists of two custom-machined aluminum attachments epoxied to the end of a beam and connected using a 1.59mm diameter alloy steel dowel. A stainless steel torsion spring is placed over the pin and attached to the aluminum body to provide a restoring torque when under rotation. The design is modeled using the piezoelectric constitutive equations to solve for voltage and power for a set of electromechanical boundary conditions. Experimental measurements on the design are achieved by bolting one end of the structure to a vibration shaker and fixing the other to a rigid framework of industrial aluminum framing material. For a given frequency of vibration, power output of the structure can be obtained by measuring voltage drop across a resistive load.

Aryanpur, Rameen M.; White, Robert D.

2012-04-01

80

Problems of vibration adjustment of gas-turbine power units

Some specific features pertinent to the vibration activity of domestically made gas-turbine power units are described, which\\u000a should be taken into account during the adjustment of gas turbines, especially during their balancing. We also show characteristic\\u000a changes in vibrations under transient conditions (before stabilization), the duration of which may exceed the time of operation\\u000a under load. Recommendations for rotor balancing

A. V. Salimon; G. I. Egorov; E. A. Tsiklin

2006-01-01

81

Stresa, Italy, 26-28 April 2006 SCALING EFFECTS FOR ELECTROMAGNETIC VIBRATIONAL POWER

Stresa, Italy, 26-28 April 2006 SCALING EFFECTS FOR ELECTROMAGNETIC VIBRATIONAL POWER GENERATORS This paper investigates how the power generated by electromagnetic based vibrational power generators scales ambient vibrations. This generally consists of using the vibrations to move a magnet relative to a coil

Boyer, Edmond

82

Multistable chain for ocean wave vibration energy harvesting

NASA Astrophysics Data System (ADS)

The heaving of ocean waves is a largely untapped, renewable kinetic energy resource. Conversion of this energy into electrical power could integrate with solar technologies to provide for round-the-clock, portable, and mobile energy supplies usable in a wide variety of marine environments. However, the direct drive conversion methodology of gridintegrated wave energy converters does not efficiently scale down to smaller, portable architectures. This research develops an alternative power conversion approach to harness the extraordinarily large heaving displacements and long oscillation periods as an excitation source for an extendible vibration energy harvesting chain. Building upon related research findings and engineering insights, the proposed system joins together a series of dynamic cells through bistable interfaces. Individual impulse events are generated as the inertial mass of each cell is pulled across a region of negative stiffness to induce local snap through dynamics; the oscillating magnetic inertial mass then generates current in a coil which is connected to energy harvesting circuitry. It is shown that linking the cells into a chain transmits impulses through the system leading to cascades of vibration and enhancement of electrical energy conversion from each impulse event. This paper describes the development of the multistable chain and ways in which realistic design challenges were addressed. Numerical modeling and corresponding experiments demonstrate the response of the chain due to slow and large amplitude input motion. Lastly, experimental studies give evidence that energy conversion efficiency of the chain for wave energy conversion is much higher than using an equal number of cells without connections.

Harne, R. L.; Schoemaker, M. E.; Wang, K. W.

2014-03-01

83

Vibrational energy redistribution in glyoxal following internal conversion

Vibrational energy redistribution in glyoxal following internal conversion R. Naaman,a) D. M 4 June 1979; accepted 10 August 1979) The vibrational redistribution of energy following internal that combination bands of low quanta of vibrations are the accepting levels in the internal conversion process

Zare, Richard N.

84

Harvesting energy from the natural vibration of human walking.

The triboelectric nanogenerator (TENG), a unique technology for harvesting ambient mechanical energy based on the triboelectric effect, has been proven to be a cost-effective, simple, and robust approach for self-powered systems. However, a general challenge is that the output current is usually low. Here, we demonstrated a rationally designed TENG with integrated rhombic gridding, which greatly improved the total current output owing to the structurally multiplied unit cells connected in parallel. With the hybridization of both the contact-separation mode and sliding electrification mode among nanowire arrays and nanopores fabricated onto the surfaces of two contact plates, the newly designed TENG produces an open-circuit voltage up to 428 V, and a short-circuit current of 1.395 mA with the peak power density of 30.7 W/m(2). Relying on the TENG, a self-powered backpack was developed with a vibration-to-electric energy conversion efficiency up to 10.62(±1.19) %. And it was also demonstrated as a direct power source for instantaneously lighting 40 commercial light-emitting diodes by harvesting the vibration energy from natural human walking. The newly designed TENG can be a mobile power source for field engineers, explorers, and disaster-relief workers. PMID:24180642

Yang, Weiqing; Chen, Jun; Zhu, Guang; Yang, Jin; Bai, Peng; Su, Yuanjie; Jing, Qingsheng; Cao, Xia; Wang, Zhong Lin

2013-12-23

85

A piezomagnetoelastic structure for broadband vibration energy harvesting

NASA Astrophysics Data System (ADS)

This letter introduces a piezomagnetoelastic device for substantial enhancement of piezoelectric power generation in vibration energy harvesting. Electromechanical equations describing the nonlinear system are given along with theoretical simulations. Experimental performance of the piezomagnetoelastic generator exhibits qualitative agreement with the theory, yielding large-amplitude periodic oscillations for excitations over a frequency range. Comparisons are presented against the conventional case without magnetic buckling and superiority of the piezomagnetoelastic structure as a broadband electric generator is proven. The piezomagnetoelastic generator results in a 200% increase in the open-circuit voltage amplitude (hence promising an 800% increase in the power amplitude).

Erturk, A.; Hoffmann, J.; Inman, D. J.

2009-06-01

86

Potential energy surfaces for vibrating hexatomic molecules

NASA Astrophysics Data System (ADS)

Extension of empirical methods enables potential energy model construction for a vibrating hexatomic molecule. Application of these methods yields a model potential energy function that describes intramolecular vibrational dynamics and spectra of glyoxal, (CHO)2. A functional form is chosen that aids in model development and promotes transferability. It features a simple, modular design, and consists of Morse interactions applied between all atomic pairs. The Morse recipe assists in model development by naturally defining efficient basis functions for representing vibrational states. Solution of a series of sub-problems provides model parameter value estimates by nonlinear least- squares fits to spectroscopic data. Model development proceeds in both rectilinear normal and curvilinear local coordinate sets, letting efficiency determine which circumstance favors one set over the other. For example, the uncoupled harmonic oscillator sub-problem is solved in normal coordinates, while the hindered rotational sub- problem with limited coupling is solved in curvilinear coordinates. Definitive model evaluation is achieved by solving variationally for the energy levels and states of the full vibrational Schrödinger equation, composed of the exact kinetic energy operator and the model potential function. In normal coordinates, both operator and basis are readily defined. In curvilinear coordinates, however, the complex analytic form of the J = 0 kinetic energy operator is derived. Due to careful coordinate selection, terms in the model describing hindered rotational motion separate out, thus promoting development of an excellent contracted basis set. The contracted basis is expanded in terms of Mathieu functions, which are found to provide a rapidly convergent basis for any general one-dimensional hindering problem. Imposing symmetry on the functions further improves the basis. The full vibrational analysis reveals that the Morse functional form is capable of describing stretch, bend, and, surprisingly, torsion motions. The model reproduces structural and spectroscopic data with reasonable accuracy. Although the full calculation is set up and solved far more easily in normal coordinates, large- amplitude states converge slowly and localized states are described poorly. Dramatically improved rates of convergence result when using curvilinear coordinates due to coordinate and basis customization.

Rempe, Susan Lynne Beamis

87

Self-powered discrete time piezoelectric vibration damper

NASA Astrophysics Data System (ADS)

Structural vibration suppression is of great interest to the aircraft industry as it can reduce the amplitude of excessive vibration in lightly damped panels caused by conditions in their operational environment. One technique of suppressing vibration is to use passive damping techniques such as constrained layered damping incorporating viscoelastic materials. However these techniques may not be acceptable because of weight concerns or extreme temperature variations. Over the past decade much work has been done by researchers on the use of piezoelectric ceramic devices, using passive and active techniques, for structural vibration suppression. The passive piezoelectric damping devices consist of a piezoelectric element and either a resistive or resonant shunt. The resonant circuit shunt, which is analogous to a mechanical vibration absorber, gives better vibration reduction compared to the resistor shunt. This device requires a large value of inductance in order to be tuned to a particular structural vibration mode. A large value inductor can be made by a using a gyrator type circuit however the circuit needs external power. A method of vibration control using a discrete time controller and piezoelectric devices is presented. That is, this paper describes the concept of a self-powered discrete time piezoelectric vibration damper which does not need tuning to the structural resonant frequency and is powered by piezoelectric elements, i.e. does not need an external power supply. This device is referred to as a strain amplitude minimization patch (STAMP) damper. A brief description of the theory used and of the scheme is presented. Also the operation of this device is compared with other 'passive' techniques, involving piezoelectric elements, such as the resistive passive damper and the parallel resonant passive damper cases. Experimental results presented, on a cantilevered beam, demonstrate the concept and show that the device, even in its current underdeveloped form, has better damping than the simple resistor damper. Measurements taken indicate that the maximum RMS tip accelerations, at resonance, are reduced by 17.3%, 62.7% and 39.5% for the resistor, parallel resonant and STAMP damper devices, respectively, when compared to the short circuit reference condition. The performance of each device is observed when the resonant frequency of the system changes when a mass is added to the tip of the cantilever. This paper also discusses areas where improvements in the performance of the STAMP damper can be achieved.

Konak, Michael J.; Powlesland, Ian G.; van der Velden, Stephen P.; Galea, Stephen C.

1997-11-01

88

Vibration behavior of fuel-element vibration suppressors for the advanced power reactor

NASA Technical Reports Server (NTRS)

Preliminary shock and vibration tests were performed on vibration suppressors for the advanced power reactor for space application. These suppressors position the fuel pellets in a pin type fuel element. The test determined the effect of varying axial clearance on the behavior of the suppressors when subjected to shock and vibratory loading. The full-size suppressor was tested in a mockup model of fuel and clad which required scaling of test conditions. The test data were correlated with theoretical predictions for suppressor failure. Good agreement was obtained. The maximum difference with damping neglected was about 30 percent. Neglecting damping would result in a conservative design.

Adams, D. W.; Fiero, I. B.

1973-01-01

89

Resonant vibrational energy transfer in ice Ih.

Fascinating anisotropy decay experiments have recently been performed on H2O ice Ih by Timmer and Bakker [R. L. A. Timmer, and H. J. Bakker, J. Phys. Chem. A 114, 4148 (2010)]. The very fast decay (on the order of 100 fs) is indicative of resonant energy transfer between OH stretches on different molecules. Isotope dilution experiments with deuterium show a dramatic dependence on the hydrogen mole fraction, which confirms the energy transfer picture. Timmer and Bakker have interpreted the experiments with a Förster incoherent hopping model, finding that energy transfer within the first solvation shell dominates the relaxation process. We have developed a microscopic theory of vibrational spectroscopy of water and ice, and herein we use this theory to calculate the anisotropy decay in ice as a function of hydrogen mole fraction. We obtain very good agreement with experiment. Interpretation of our results shows that four nearest-neighbor acceptors dominate the energy transfer, and that while the incoherent hopping picture is qualitatively correct, vibrational energy transport is partially coherent on the relevant timescale. PMID:24985650

Shi, L; Li, F; Skinner, J L

2014-06-28

90

Self-powered circuit for broadband, multimodal piezoelectric vibration control

Vibration control using piezoelectric actuators has experienced a strong development these last years. Particularly, non-linear techniques have been proven to be low-cost and efficient ways of damping, with self-powering capabilities. This paper deals with one of these methods, the so-called self-powered synchronized switch damping on inductor (SSDI). Its principles rely on switching intermittently the piezoelement on a resonant circuit. Particularly,

Mickaël Lallart; Élie Lefeuvre; Claude Richard; Daniel Guyomar

2008-01-01

91

Vibration-to-electric energy conversion

Abstract: A system is proposed to convert ambient mechanicalvibration into electrical energy for use in powering autonomouslow power electronic systems. The energy is transduced throughthe use of a variable capacitor. Using microelectromechanical systems(MEMS) technology, such a device has been designed for thesystem. A low-power controller IC has been fabricated in a 0.6- mCMOS process and has been tested and measured

Scott Meninger; Jose Oscar Mur-miranda; Rajeevan Amirtharajah; Anantha P. Chandrakasan; Jeffrey H. Lang

2001-01-01

92

MEMS electrostatic vibration energy harvester without switches and inductive elements

NASA Astrophysics Data System (ADS)

The paper is devoted to a novel study of monophase MEMS electrostatic Vibration Energy Harvester (e-VEH) with conditioning circuit based on Bennet's doubler. Unlike the majority of conditioning circuits that charge a power supply, the circuit based on Bennet's doubler is characterized by the absence of switches requiring additional control electronics, and is free from hardly compatible with batch fabrication process inductive elements. Our experiment with a 0.042 cm3 batch fabricated MEMS e-VEH shows that a pre-charged capacitor as a power supply causes a voltage increase, followed by a saturation which was not reported before. This saturation is due to the nonlinear dynamics of the system and the electromechanical damping that is typical for MEMS. It has been found that because of that coupled behavior there exists an optimal power supply voltage at which output power is maximum. At 187 Hz / 4 g external vibrations the system is shown to charge a 12 V supply with a output power of 1.8 ?W.

Dorzhiev, V.; Karami, A.; Basset, P.; Dragunov, V.; Galayko, D.

2014-11-01

93

New nonlinear vibration energy harvesters based on PVDF hybrid fluid diaphragm

NASA Astrophysics Data System (ADS)

A low resonance frequency piezoelectric energy harvesting using a hybrid fluid diaphragm (HFD) is presented. This paper describes the design, fabrication and measurement of such device for harvesting energy from environmental vibrations. The HFD consists in an incompressible fluid confined between two thin piezoelectric membranes. The output voltage and power of the PVDF HFD are studied based on experimental and simulation results. Compared with conventional vibration harvester, this proposed solution is very simple and suitable for miniaturization and integration.

Huet, F.; Formosa, F.; Badel, A.

2014-11-01

94

NASA Astrophysics Data System (ADS)

Efficiency of vibrational energy transfer (VET) in vibrational quasicontinuum of triplet states was estimated from the dependence of time-resolved delayed fluorescence of benzophenone and anthraquinone on bath gas pressure. The negative temperature dependence for vibration-vibration (V-V) and positive for vibration-translation (V-T) energy transfers from benzophenone and anthraquinone to bath gases (C 2H 4, SF 6, CCl 4, C 5H 12) were obtained between 373 and 553 K. Polarizability and dipole moment of colliding molecules seem to affect the efficiency of V-V relaxation. These data reflect the dominance of long-range attractive interactions in V-V energy transfer and short-range repulsive interactions in V-T energy transfer.

Zalesskaya, G. A.; Yakovlev, D. L.; Sambor, E. G.

2000-08-01

95

NASA Astrophysics Data System (ADS)

Kinetic energy losses and vibrational excitation in scattering of a polyatomic molecule from a surface at hyperthermal energies were studied for the first time as a function of the average vibrational energy of the incident molecule. C60 molecules with variable amounts of vibrational energy in the range of < Ev = 7-15 eV and fixed kinetic energy were prepared in a helium seeded beam and scattered from a carbonized nickel surface. The primary beam kinetic energies and kinetic energy losses were measured with an accuracy of +/- 0.1 eV while vibrational energies before and after the scattering event were measured with an accuracy of +/- 0.25 eV (most probable values of the corresponding energy distributions). The vibrational thermometry method employed is shown to be practically independent of the specific model relating vibrational temperature to average vibrational energy (canonical vs. finite heat bath). Experiments were done at two different scattering angles corresponding to near normal and near grazing conditions, and for both angles it was found that the kinetic energy loss is independent of the initial vibrational energy to within 0.2 eV. The collisional vibrational excitation showed a weak inverse dependence on initial vibrational energy for both scattering angles. For the lowest incident C60 vibrational energy (< Ev = 9.8 eV) and near normal scattering (30.7 eV in the normal impact energy component) this excitation was found to be about 5% of the impact kinetic energy. We discuss these results in relation to possible mechanisms for normal and tangential energy transfer in a single C60-surface collision at the hyperthermal (10-50 eV) energy range.

Bekkerman, A.; Tsipinyuk, B.; Budrevich, A.; Kolodney, E.

1997-11-01

96

Vibrational energy transfer in ultracold molecule - molecule collisions

We present a rigorous study of vibrational relaxation in p-H2 + p-H2 collisions at cold and ultracold temperatures and identify an efficient mechanism of ro-vibrational energy transfer. If the colliding molecules are in different rotational and vibrational levels, the internal energy may be transferred between the molecules through an extremely state-selective process involving simultaneous conservation of internal energy and total rotational angular momentum. The same transition in collisions of distinguishable molecules corresponds to the rotational energy transfer from one vibrational state of the colliding molecules to another.

Goulven Quéméner; Naduvalath Balakrishnan; Roman V. Krems

2007-09-19

97

A Bistable Vibration Energy Harvester with Closed Magnetic Circuit

NASA Astrophysics Data System (ADS)

In this work, to increase magnetic flux passing through the electric coil in a bistable vibration energy harvester, the magnetic circuit is made closed by introducing two coil systems which have magnetic core in their axis holes. The magnetic resistance of the magnetic circuit, composed of silicon steel and thin air gaps, is supressed to be small. The double well potential is realized from the spring force and nonlinear magnetic force between the magnets and the magnetic core. Two harvesters with opened and closed magnetic circuits are manufactured for comparison. It is also shown that the closed magnetic circuit can effectively improve the output power.

Sato, Takahiro; Sugisawa, Takeshi; Igarashi, Hajime

2014-11-01

98

Vibration-based energy harvesting with stacked piezoelectrets

Vibration-based energy harvesters with multi-layer piezoelectrets (ferroelectrets) are presented. Using a simple setup with nine layers and a seismic mass of 8?g, it is possible to generate a power up to 1.3?µW at 140?Hz with an input acceleration of 1g. With better coupling between seismic mass and piezoelectret, and thus reduced damping, the power output of a single-layer system is increased to 5?µW at 700?Hz. Simulations indicate that for such improved setups with 10-layer stacks, utilizing seismic masses of 80?g, power levels of 0.1 to 1 mW can be expected below 100?Hz.

Pondrom, P., E-mail: ppondrom@nt.tu-darmstadt.de [Institute for Telecommunications Technology, Technische Universität Darmstadt, Merckstr. 25, 64283 Darmstadt (Germany); System Reliability and Machine Acoustics SzM, Technische Universität Darmstadt, Magdalenenstr. 4, 64289 Darmstadt (Germany); Hillenbrand, J.; Sessler, G. M. [Institute for Telecommunications Technology, Technische Universität Darmstadt, Merckstr. 25, 64283 Darmstadt (Germany); Bös, J.; Melz, T. [System Reliability and Machine Acoustics SzM, Technische Universität Darmstadt, Magdalenenstr. 4, 64289 Darmstadt (Germany)

2014-04-28

99

Energy harvester array using piezoelectric circular diaphragm for broadband vibration

NASA Astrophysics Data System (ADS)

A piezoelectric generator fabricated by multiple circular diaphragm piezoelectric harvesters array is provided to harvest power over a broad range of frequencies. Four harvesters with varies tip masses are incorporated on a board with an area of 98 × 98 mm2. In this case, four strong output power peaks are obtained over frequencies from 120 Hz to 225 Hz. With an optimum load resistance of 15 k?, the value of four output power peaks is, respectively, 5.14, 6.65, 9.7, and 10 mW for the generator under an acceleration of 9.8 m/s2. By choosing an appropriate combination of tip masses with piezoelectric elements in array, the frequency range of energy harvesting can be obviously widened to meet the broadband vibration.

Xiao, Zhao; Yang, Tong qing; Dong, Ying; Wang, Xiu cai

2014-06-01

100

Smart nanocoated structure for energy harvesting at low frequency vibration

NASA Astrophysics Data System (ADS)

Increasing demands of energy which is cleaner and has an unlimited supply has led development in the field of energy harvesting. Piezoelectric materials can be used as a means of transforming ambient vibrations into electrical energy that can be stored and used to power other devices. With the recent surge of micro scale devices, piezoelectric power generation can provide a convenient alternative to traditional power sources. In this research, a piezoelectric power generator composite prototype was developed to maximize the power output of the system. A lead zirconate titanate (PZT) composite structure was formed and mounted on a cantilever bar and was studied to convert vibration energy of the low range vibrations at 30 Hz--1000 Hz. To improve the performance of the PZT, different coatings were made using different percentage of Ferrofluid (FNP) and Zinc Oxide nanoparticles (ZnO) and binder resin. The optimal coating mixture constituent percentage was based on the performance of the composite structure formed by applying the coating on the PZT. The fabricated PZT power generator composite with an effective volume of 0.062 cm3 produced a maximum of 44.5 ?W, or 0.717mW/cm3 at its resonant frequency of 90 Hz. The optimal coating mixture had the composition of 59.9%FNP + 40% ZnO + 1% Resin Binder. The coating utilizes the opto-magneto-electrical properties of ZnO and Magnetic properties of FNP. To further enhance the output, the magneto-electric (ME) effect was increased by subjecting the composite to magnetic field where coating acts as a magnetostrictive material. For the effective volume of 0.0062 cm 3, the composite produced a maximum of 68.5 ?W, or 1.11mW/cm 3 at its resonant frequency of 90 Hz at 160 gauss. The optimal coating mixture had the composition of 59.9% FNP + 40% ZnO + 1% Resin Binder. This research also focused on improving the efficiency of solar cells by utilizing the magnetic effect along with gas plasma etching to improve the internal reflection. Preliminary results showed an improvement in solar cell efficiency from 14.6% to 17.1%.

Sharma, Sudhanshu

101

Study of vibrational energy transfer at a liquid tin surface

NASA Astrophysics Data System (ADS)

Single collision vibrational energy transfer for a canonical ensemble (T=300K) of cyclobutene molecules at a liquid tin surface was studied at temperatures from 500K to 775K. Transport above the reaction threshold for isomerization to butadiene was used as the criterion for efficiency of vibrational energy accommodation. The surface was found to function as a strong collider below 550 K. Experiments both above and below the freezing point revealed no discontinuity in the vibrational accommodation efficiency.

Nilsson, W. B.; Rabinovitch, B. S.

1984-08-01

102

A Hybrid Indoor Ambient Light and Vibration Energy Harvester for Wireless Sensor Nodes

To take advantage of applications where both light and vibration energy are available, a hybrid indoor ambient light and vibration energy harvesting scheme is proposed in this paper. This scheme uses only one power conditioning circuit to condition the combined output power harvested from both energy sources so as to reduce the power dissipation. In order to more accurately predict the instantaneous power harvested from the solar panel, an improved five-parameter model for small-scale solar panel applying in low light illumination is presented. The output voltage is increased by using the MEMS piezoelectric cantilever arrays architecture. It overcomes the disadvantage of traditional MEMS vibration energy harvester with low voltage output. The implementation of the maximum power point tracking (MPPT) for indoor ambient light is implemented using analog discrete components, which improves the whole harvester efficiency significantly compared to the digital signal processor. The output power of the vibration energy harvester is improved by using the impedance matching technique. An efficient mechanism of energy accumulation and bleed-off is also discussed. Experiment results obtained from an amorphous-silicon (a-Si) solar panel of 4.8 × 2.0 cm2 and a fabricated piezoelectric MEMS generator of 11 × 12.4 mm2 show that the hybrid energy harvester achieves a maximum efficiency around 76.7%. PMID:24854054

Yu, Hua; Yue, Qiuqin; Zhou, Jielin; Wang, Wei

2014-01-01

103

A hybrid indoor ambient light and vibration energy harvester for wireless sensor nodes.

To take advantage of applications where both light and vibration energy are available, a hybrid indoor ambient light and vibration energy harvesting scheme is proposed in this paper. This scheme uses only one power conditioning circuit to condition the combined output power harvested from both energy sources so as to reduce the power dissipation. In order to more accurately predict the instantaneous power harvested from the solar panel, an improved five-parameter model for small-scale solar panel applying in low light illumination is presented. The output voltage is increased by using the MEMS piezoelectric cantilever arrays architecture. It overcomes the disadvantage of traditional MEMS vibration energy harvester with low voltage output. The implementation of the maximum power point tracking (MPPT) for indoor ambient light is implemented using analog discrete components, which improves the whole harvester efficiency significantly compared to the digital signal processor. The output power of the vibration energy harvester is improved by using the impedance matching technique. An efficient mechanism of energy accumulation and bleed-off is also discussed. Experiment results obtained from an amorphous-silicon (a-Si) solar panel of 4.8 × 2.0 cm2 and a fabricated piezoelectric MEMS generator of 11 × 12.4 mm2 show that the hybrid energy harvester achieves a maximum efficiency around 76.7%. PMID:24854054

Yu, Hua; Yue, Qiuqin; Zhou, Jielin; Wang, Wei

2014-01-01

104

Vibration-assisted resonance in photosynthetic excitation-energy transfer

NASA Astrophysics Data System (ADS)

Understanding how the effectiveness of natural photosynthetic energy-harvesting systems arises from the interplay between quantum coherence and environmental noise represents a significant challenge for quantum theory. Recently it has begun to be appreciated that discrete molecular vibrational modes may play an important role in the dynamics of such systems. Here we present a microscopic mechanism by which intramolecular vibrations may be able to contribute to the efficiency and directionality of energy transfer. Excited vibrational states create resonant pathways through the system, supporting fast and efficient energy transport. Vibrational damping together with the natural downhill arrangement of molecular energy levels gives intrinsic directionality to the energy flow. Analytical and numerical results demonstrate a significant enhancement of the efficiency and directionality of energy transport that can be directly related to the existence of resonances between vibrational and excitonic levels.

Irish, E. K.; Gómez-Bombarelli, R.; Lovett, B. W.

2014-07-01

105

Resonance tracking and vibration stablilization for high power ultrasonic transducers.

Resonant frequency shift and electrical impedance variation are common phenomena in the application of high power ultrasonic transducers, e.g. in focused ultrasound surgery and in cutting. They result in low power efficiency and unstable vibration amplitude. To solve this problem, a driving and measurement system has been developed to track the resonance of high power transducers and to stabilise their vibration velocity. This has the ability to monitor the operating and performance parameters of the ultrasonic transducers in real time. The configuration of the system, with its control algorithm implemented in LabVIEW (National Instruments, Newbury, UK), ensures flexibility to suit different transducers and load conditions. In addition, with different programs, it can be utilised as a high power impedance analyser or an instantaneous electrical power measurement system for frequencies in the MHz range. The effectiveness of this system has been demonstrated in detailed studies. With it, high transducer performance at high power can be achieved and monitored in real time. PMID:23928264

Kuang, Y; Jin, Y; Cochran, S; Huang, Z

2014-01-01

106

Recent evidence suggests that quantum effects may have functional importance in biological light-harvesting systems. Along with delocalized electronic excitations, it is now suspected that quantum coherent interactions with certain near-resonant vibrations contribute to light-harvesting performance. However, the actual quantum advantage offered by such coherent vibrational interactions has not yet been established. We investigate a quantum design principle, whereby coherent exchange of single energy quanta between electronic and vibrational degrees of freedom can enhance a light-harvesting system's power above what is possible by thermal mechanisms alone. We present a prototype quantum heat engine which cleanly illustrates this quantum design principle, and quantify its quantum advantage using thermodynamic measures of performance. We also demonstrate the principle's applicability for realistic biological structures.

Killoran, Nathan; Plenio, Martin B

2014-01-01

107

Recent evidence suggests that quantum effects may have functional importance in biological light-harvesting systems. Along with delocalized electronic excitations, it is now suspected that quantum coherent interactions with certain near-resonant vibrations contribute to light-harvesting performance. However, the actual quantum advantage offered by such coherent vibrational interactions has not yet been established. We investigate a quantum design principle, whereby coherent exchange of single energy quanta between electronic and vibrational degrees of freedom can enhance a light-harvesting system's power above what is possible by thermal mechanisms alone. We present a prototype quantum heat engine which cleanly illustrates this quantum design principle, and quantify its quantum advantage using thermodynamic measures of performance. We also demonstrate the principle's applicability for realistic biological structures.

Nathan Killoran; Susana F. Huelga; Martin B. Plenio

2014-12-12

108

NASA Astrophysics Data System (ADS)

This paper presents an optimal design for a system comprising a nonlinear energy sink (NES) and a piezoelectric-based vibration energy harvester attached to a free-free beam under shock excitation. The energy harvester is used for scavenging vibration energy dissipated by the NES. Grounded and ungrounded configurations are examined and the systems parameters are optimized globally to both maximize the dissipated energy by the NES and increase the harvested energy by piezoelectric element. A satisfactory amount of energy has been harvested as electric power in both configurations. The realization of nonlinear vibration control through one-way irreversible nonlinear energy pumping and optimizing the system parameters result in acquiring up to 78 percent dissipation of the grounded system energy.

Nili Ahmadabadi, Z.; Khadem, S. E.

2014-09-01

109

A chaotic vibration energy harvester using magnetic material

NASA Astrophysics Data System (ADS)

This paper presents a new wideband electromagnetic vibration energy harvester (VEH) composed of a magnetic core embedded into the coil axis. The magnetic core generates a nonlinear magnetic force, which gives rise to the nonlinearity in the behavior of the VEH. Moreover, the magnetic core increases the flux linkage with the coil. These features improve the operational bandwidth and output power of the VEH. Numerical analysis and experimental measurements reveal that the operational bandwidth of the proposed VEH is over 30 Hz in which the output power is kept about 0.1 mW. Moreover, the proposed VEH operates by complicated oscillation due to nonlinear forces acting on the oscillator. Evaluation of the Lyapunov exponent for the measured oscillation suggests that the proposed VEH produces chaotic oscillation.

Sato, Takahiro; Igarashi, Hajime

2015-02-01

110

Resonant frequency tuning of an industrial vibration energy harvester

NASA Astrophysics Data System (ADS)

This paper presents preliminary results of tuning the resonant frequency of two industrial vibration energy harvesters. The VEH-450 from Ferro Solutions and the PMG17-50 from Perpetuum were tested using discrete reactive electrical loads. The former could be tuned to +0.5 Hz and -2 Hz from its natural resonant frequency of 50.5 Hz at 0.1g. The latter, however, has a broadband output power spectrum that spans ±10 Hz and its output voltage saturates at 7 Vrms, thereby rendering it un-tunable using the method presented here. A comparison of output power between a tuned VEH-450 and an un-tuned PMG17-50, normalised by harvester weight, shows that the former outperforms the latter only at a tuned frequency of 49.8 Hz. A discussion of a resonant frequency tuning circuit that can be fitted to an existing harvester without making modifications to the harvester is presented.

Toh, T. T.; Wright, S. W.; Mitcheson, P. D.

2014-11-01

111

Piezoelectric energy harvesting devices for low frequency vibration applications

NASA Astrophysics Data System (ADS)

Energy harvesting, a process of capturing ambient waste energy and converting it into usable electricity, has been attracting more and more researchers' interest because of the limitations of traditional power sources, the increasing demands upon mobile devices such as wireless sensor networks, and the recent advent of the extremely low power electrical and mechanical devices such as microelectromechanical systems (MEMS). In this research, bulk- and wafer-scale of piezoelectric power generator prototypes were developed. The Lead Zirconate Titanate (PZT) bimorph cantilever in bulk scale with a big proof mass at the free end tip was studied to convert ambient vibration energy of 100 Hz and above 1g (1g = 9.81 m/s2) acceleration amplitudes. The optimal design was based on matching the resonant frequency of the device with the environmental exciting frequency, and balancing the power output and the fracture safety factor. The fabricated PZT power generator with an effective volume of 0.0564 cm3 and a safety factor of 10g can produce 6.21 Vpk, 257 microW, or 4558 microW/cm 3 with an optimal resistive load of 75 kO from 1g acceleration at its resonant frequency of 97.6 Hz. To overcome the high fragility of PZT, substitute piezoelectric materials, Macro Fiber Composite (MFC) and polyvinylidene fluoride (PVDF), and alternative operational ambient for power generators were investigated for high vibration amplitude applications. Before fabricating piezoelectric power generators in wafer scale, interlayer effects on the properties of PZT thin film were surveyed. The fabricated device based on Si wafer, with a beam dimension about 4.800 mm x 0.400 mm x 0.036 mm and an integrated Si mass dimension about 1.360 mm x 0.940 mm x 0.456 mm produced 160 mVpk, 2.13 microW, or 3272 microW/cm3 with the optimal resistive load of 6 kO from 2g acceleration at its resonant frequency of 461.15 Hz. To precisely control the resonant frequency of the power generator, Si on insulator (SOI) wafer substitutes for Si wafer. The resonant frequency of the fabricated device is as low as about 184 Hz. The difference between the calculated and measured resonant frequency has been decreased to 4.25%.

Shen, Dongna

112

In general, vibration energy harvesting is the scavenging of ambient vibration by transduction of mechanical kinetic energy into electrical energy. Many mechanical or electro-mechanical systems produce mechanical vibrations. ...

Trimble, A. Zachary

2011-01-01

113

Vibrational Energy Relaxation of "Tailored" Hemes in Myoglobin Following Ligand Photolysis Supports or dissociation, heme proteins undergo vibrational energy relaxation (VER). Understanding the time scales and mechanisms of vibrational energy transfer is an essential component of a complete understanding

Straub, John E.

114

NASA Astrophysics Data System (ADS)

We present electroelastic modeling, analytical and numerical solutions, and experimental validations of piezoelectric energy harvesting from broadband random vibrations. The modeling approach employed herein is based on a distributed-parameter electroelastic formulation to ensure that the effects of higher vibration modes are included, since broadband random vibrations, such as Gaussian white noise, might excite higher vibration modes. The goal is to predict the expected value of the power output and the mean-square shunted vibration response in terms of the given power spectral density (PSD) or time history of the random vibrational input. The analytical method is based on the PSD of random base excitation and distributed-parameter frequency response functions of the coupled voltage output and shunted vibration response. The first of the two numerical solution methods employs the Fourier series representation of the base acceleration history in an ordinary differential equation solver while the second method uses an Euler-Maruyama scheme to directly solve the resulting electroelastic stochastic differential equations. The analytical and numerical simulations are compared with several experiments for a brass-reinforced PZT-5H bimorph under different random excitation levels. The simulations exhibit very good agreement with the experimental measurements for a range of resistive electrical boundary conditions and input PSD levels. It is also shown that lightly damped higher vibration modes can alter the expected power curve under broadband random excitation. Therefore, the distributed-parameter modeling and solutions presented herein can be used as a more accurate alternative to the existing single-degree-of-freedom solutions for broadband random vibration energy harvesting.

Zhao, S.; Erturk, A.

2013-01-01

115

Vibration amplitude of transducer's elements is the influential parameters in the performance of high power airborne ultrasonic transducers to control the optimum vibration without material yielding. The vibration amplitude of elements of provided high power airborne transducer was determined by measuring temperature of the provided high power airborne transducer transducer's elements. The results showed that simple thermocouples can be used both to measure the vibration amplitude of transducer's element and an indicator to power transmission to the air. To verify our approach, the power transmission to the air has been investigated by other common method experimentally. The experimental results displayed good agreement with presented approach. PMID:24246149

Saffar, Saber; Abdullah, Amir

2014-03-01

116

Energy harvesting from underwater torsional vibrations of a patterned ionic polymer metal composite

NASA Astrophysics Data System (ADS)

In this paper, we study underwater energy harvesting from torsional vibrations of an ionic polymer metal composite (IPMC) with patterned electrodes. We focus on harmonic base excitation of a centimeter-size IPMC, which is modeled as a slender beam with thin cross-section vibrating in a viscous fluid. Large-amplitude torsional vibrations are described using a complex hydrodynamic function, which accounts for added mass and nonlinear hydrodynamic damping from the surrounding fluid. A linear black box model is utilized to predict the IPMC electrical response as a function of the total twist angle. Model parameters are identified from in-air transient response, underwater steady-state vibrations, and electrical discharge experiments. The resulting electromechanical model allows for predicting energy harvesting from the IPMC as a function of the shunting resistance and the frequency and amplitude of the base excitation. Model results are validated against experimental findings that demonstrate power harvesting densities on the order of picowatts per millimeter cubed.

Cha, Youngsu; Shen, Linfeng; Porfiri, Maurizio

2013-05-01

117

NASA Astrophysics Data System (ADS)

Wireless sensor networks (WSNs) have the potential to transform engineering infrastructure, manufacturing, and building controls by allowing condition monitoring, asset tracking, demand response, and other intelligent feedback systems. A wireless sensor node consists of a power supply, sensor(s), power conditioning circuitry, radio transmitter and/or receiver, and a micro controller. Such sensor nodes are used for collecting and communicating data regarding the state of a machine, system, or process. The increasing demand for better ways to power wireless devices and increase operation time on a single battery charge drives an interest in energy harvesting research. Today, wireless sensor nodes are typically powered by a standard single-charge battery, which becomes depleted within a relatively short timeframe depending on the application. This introduces tremendous labor costs associated with battery replacement, especially when there are thousands of nodes in a network, the nodes are remotely located, or widely-distributed. Piezoelectric vibration energy harvesting presents a potential solution to the problems associated with too-short battery life and high maintenance requirements, especially in industrial environments where vibrations are ubiquitous. Energy harvester designs typically use the harvester to trickle charge a rechargeable energy storage device rather than directly powering the electronics with the harvested energy. This allows a buffer between the energy harvester supply and the load where energy can be stored in a "tank". Therefore, the harvester does not need to produce the full required power at every instant to successfully power the node. In general, there are tens of microwatts of power available to be harvested from ambient vibrations using micro scale devices and tens of milliwatts available from ambient vibrations using meso scale devices. Given that the power requirements of wireless sensor nodes range from several microwatts to about one hundred milliwatts and are falling steadily as improvements are made, it is feasible to use energy harvesting to power WSNs. This research begins by presenting the results of a thorough survey of ambient vibrations in the machine room of a large campus building, which found that ambient vibrations are low frequency, low amplitude, time varying, and multi-frequency. The modeling and design of fixed-frequency micro scale energy harvesters are then presented. The model is able to take into account rotational inertia of the harvester's proof mass and it accepts arbitrary measured acceleration input, calculating the energy harvester's voltage as an output. The fabrication of the micro electromechanical system (MEMS) energy harvesters is discussed and results of the devices harvesting energy from ambient vibrations are presented. The harvesters had resonance frequencies ranging from 31 - 232 Hz, which was the lowest reported in literature for a MEMS device, and produced 24 pW/g2 - 10 nW/g2 of harvested power from ambient vibrations. A novel method for frequency modification of the released harvester devices using a dispenser printed mass is then presented, demonstrating a frequency shift of 20 Hz. Optimization of the MEMS energy harvester connected to a resistive load is then presented, finding that the harvested power output can be increased to several microwatts with the optimized design as long as the driving frequency matches the harvester's resonance frequency. A framework is then presented to allow a similar optimization to be conducted with the harvester connected to a synchronously switched pre-bias circuit. With the realization that the optimized energy harvester only produces usable amounts of power if the resonance frequency and driving frequency match, which is an unrealistic situation in the case of ambient vibrations which change over time and are not always known

Miller, Lindsay Margaret

118

Power absorption in women and men exposed to hand-arm vibration

Objectives.. The aim of the study was to determine whether there are gender differences as regards the quantity of absorbed power, i.e., vibration absorption per unit of time, during exposure to vibration from a specially constructed handle.Methods.. The study was conducted on 24 subjects (12 female and 12 male). The experiments were performed with exposure in two vibration directions, Xh,

Sonya H. Bylund; Lage Burström

2003-01-01

119

Magnetic induction systems to harvest energy from mechanical vibrations

This thesis documents the design process for magnetic induction systems to harvest energy from mechanical vibrations. Two styles of magnetic induction systems - magnet-through-coil and magnet-across-coils - were analyzed. ...

Jonnalagadda, Aparna S

2007-01-01

120

Enhanced vibration based energy harvesting using embedded acoustic black holes

NASA Astrophysics Data System (ADS)

In this paper, we investigate the use of dynamic structural tailoring via the concept of an Acoustic Black Hole (ABH) to enhance the performance of piezoelectric based energy harvesting from operational mechanical vibrations. The ABH is a variable thickness structural feature that can be embedded in the host structure allowing a smooth reduction of the phase velocity while minimizing the amplitude of reflected waves. The ABH thickness variation is typically designed according to power-law profiles. As a propagating wave enters the ABH, it is progressively slowed down while its wavelength is compressed. This effect results in structural areas with high energy density that can be exploited effectively for energy harvesting. The potential of ABH for energy harvesting is shown via a numerical study based on fully coupled finite element electromechanical models of an ABH tapered plate with surface mounted piezo-transducers. The performances of the novel design are evaluated by direct comparison with a non-tapered structure in terms of energy ratios and attenuation indices. Results show that the tailored structural design allows a drastic increase in the harvested energy both for steady state and transient excitation. Performance dependencies of key design parameters are also investigated.

Zhao, L.; Semperlotti, F.; Conlon, S. C.

2014-03-01

121

Structural vibration control by synchronized switch damping energy transfer

The synchronized switch damping (SSD) technique has been demonstrated as an efficient means of suppressing structure vibrations. This paper presents a novel SSD technique based on an energy transfer (SSDET) scheme that transmits energy from an energy-source structure to a target structure in order to damp the latter. As a matter of fact, the transferred energy enhanced the synchronized switch

Kaixiang Li; Jean-Yves Gauthier; Daniel Guyomar

2011-01-01

122

Vibration Energy Harvesting Characterization of 1 cm2 Poly(vinylidene fluoride) Generators in Vacuum

NASA Astrophysics Data System (ADS)

In this study, poly(vinylidene fluoride) (PVDF) was used as a piezoelectric element to fabricate small size (two-dimensional area <1 cm2) generators with low resonant frequency (about 100 Hz) for matching the frequency of vibration sources. To clarify the effect of the air damping on the vibration energy harvesting, PVDF generators were investigated in three measurement conditions: “unpackaged in air”, “packaged in air”, and “unpackaged in vacuum”. It was found that the output power of generators “unpackaged in vacuum” was almost twice that of generators “packaged in air” at 0.5g acceleration. With the increase in vibration acceleration, the output power of generators “unpackaged in vacuum” rapidly increased in a quadratic relationship with the acceleration at low acceleration level, and then the increasing ratio decreased at high acceleration. At 4.31g acceleration, the output power reached 100.833 µW.

Cao, Ziping; Zhang, Jinya; Kuwano, Hiroki

2011-09-01

123

Vibrational energy transfer dynamics in ruthenium polypyridine transition metal complexes.

Understanding the dynamics of the initial stages of vibrational energy transfer in transition metal complexes is a challenging fundamental question which is also of crucial importance for many applications, such as improving the performance of solar devices or photocatalysis. The present study investigates vibrational energy transport in the ground and the electronic excited state of Ru(4,4'-(COOEt)2-2,2-bpy)2(NCS)2, a close relative of the efficient "N3" dye used in dye-sensitized solar cells. Using the emerging technique of ultrafast two-dimensional infrared spectroscopy, we show that, similarly to other transition-metal complexes, the central Ru heavy atom acts as a "bottleneck" making the energy transfer from small ligands with high energy vibrational stretching frequencies less favorable and thereby affecting the efficiency of vibrational energy flow in the complex. Comparison of the vibrational relaxation times in the electronic ground and excited state of Ru(4,4'-(COOEt)2-2,2-bpy)2(NCS)2 shows that it is dramatically faster in the latter. We propose to explain this observation by the intramolecular electrostatic interactions between the thiocyanate group and partially oxidised Ru metal center, which increase the degree of vibrational coupling between CN and Ru-N modes in the excited state thus reducing structural and thermodynamic barriers that slow down vibrational relaxation and energy transport in the electronic ground state. As a very similar behavior was earlier observed in another transition-metal complex, Re(4,4'-(COOEt)2-2,2'-bpy)(CO)3Cl, we suggest that this effect in vibrational energy dynamics might be common for transition-metal complexes with heavy central atoms. PMID:25463745

Fedoseeva, Marina; Delor, Milan; Parker, Simon C; Sazanovich, Igor V; Towrie, Michael; Parker, Anthony W; Weinstein, Julia A

2015-01-21

124

NASA Astrophysics Data System (ADS)

In this paper, a wide-band vibration energy harvester using a nonlinear hardening oscillator with self-excitation circuit is presented. A vibration energy harvester is one of the energy-harvesting devices that collects unused energy from vibrating environment. For the conventional linear vibration energy harvester, the resonance frequency is matched to the source frequency, and the mechanical Q factor is designed as large as possible to maximize the oscillator's amplitude. The large Q factor, however, bounds the resonance in a narrow frequency band, and the performance of the vibration energy harvester can become extremely worth when the frequency of the vibration source fluctuates. As is well known, the resonance frequency band can be expanded by introducing a hardening (or softening) nonlinear oscillator. However, it is difficult for the nonlinear vibration energy harvester to maintain the regenerated power constant because such nonlinear oscillator can have multiple stable steady-state solutions in the resonance band. In this paper, a control law that switches the load resistance between positive and negative values according to the instantaneous displacement and the velocity is proposed to give the oscillator a self-excitation capability, which ensures the oscillator entrained by the excitation only in the largest amplitude solution. Moreover, an adaptive adjustment of the control law is proposed to quicken the entrainment process. Numerical analysis shows that the nonlinear vibration energy harvester with resistance switching can maintain the large amplitude response even when the excitation frequency abruptly changes.

Masuda, Arata; Senda, Atsuko

2012-04-01

125

Design improvements for an electret-based MEMS vibrational electrostatic energy harvester

NASA Astrophysics Data System (ADS)

This paper presents several improvements to the design of an electret-based MEMS vibrational electrostatic energy harvester that have led to a two orders of magnitude increase in power compared to a previously presented device. The device in this paper has a footprint of approximately 1 cm2 and generated 175 ?W. The following two improvements to the design are discussed: the electrical connection principle of the harvester and the electrode geometrical configuration. The measured performance of the device is compared with simulations. When exited by sinusoidal vibration, a device employing the two design improvements but with a higher resonance frequency and higher electret potential generated 495 ?W AC power, which is the highest reported value for electret-based MEMS vibrational electrostatic energy harvesters with a similar footprint. This makes this device a promising candidate for the targeted application of wireless tire pressure monitoring systems (TPMS).

Altena, G.; Renaud, M.; Elfrink, R.; Goedbloed, M. H.; de Nooijer, C.; van Schaijk, R.

2013-12-01

126

A Detailed Level Kinetics Model of NO Vibrational Energy Distributions

NASA Technical Reports Server (NTRS)

Several contemporary problems have pointed to the desirability of a detailed level kinetics approach to modeling the distribution of vibrational energy in NO. Such a model is necessary when vibrational redistribution reactions are insufficient to maintain a Boltzmann distribution over the vibrational energy states. Recent calculations of the rate constant for the first reaction of the Zeldovich mechanism (N2 + O (goes to) NO + N) have suggested that the product NO is formed in high vibrational states. In shock layer flowfields, the product NO molecules may experience an insufficient number of collisions to establish a Boltzmann distribution over vibrational states, thus necessitating a level kinetics model. In other flows, such as expansions of high temperature air, fast, near-resonance vibrational energy exchanges with N2 and O2 may also require a level specific model for NO because of the relative rates of vibrational exchange and redistribution. The proposed report will integrate computational and experimental components to construct such a model for the NO molecule.

Sharma, Surendra P.; Gilmore, John; Cavolowsky, John A. (Technical Monitor)

1996-01-01

127

Development and experiments of a micro piezoelectric vibration energy storage device

NASA Astrophysics Data System (ADS)

According to the difficult replacement and poor endurance of the battery for wireless sensor network nodes, a micro piezoelectric vibration energy storage device was developed in this paper. The electric generating performance of the device was then tested on a self-made experimental system. It is shown that the developed energy storage device can collect effectively surrounding vibrations. What is more, the inherent frequency of the device can be expanded by adjusting the span between its two piezoelectric vibrators. It is also found that the output of the device depends badly on the external load resistance. With the increasing of load resistance, the output voltage increases while the output power increases first then decreases. The output power has an optimal associated load resistance. The output power achieves a maximum value 115.2 ?W when the load resistance is 200 k?. With the energy storing circuit, the output electric energy of the device can effectively act as a power source for any low power micro electron devices such as wireless sensor network nodes. It is believed that this work may be practical for energy supplying of the low power micro electron devices.

Chen, Guangzhu; Meng, Qingchun; Fu, Hailing; Bao, Jiusheng

2013-10-01

128

NASA Astrophysics Data System (ADS)

Regenerative semi-active suspensions can capture the previously dissipated vibration energy and convert it to usable electrical energy for powering on-board electronic devices, while achieve both the better ride comfort and improved road handling performance at the same time when certain control is applied. To achieve this objective, the power electronics interface circuit connecting the energy harvester and the electrical loads, which can perform simultaneous vibration control and energy harvesting function is in need. This paper utilized a buck-boost converter for simultaneous semi-active vibration control and energy harvesting with electromagnetic regenerative shock absorber, which utilizes a rotational generator to converter the vibration energy to electricity. It has been found that when the circuit works in discontinuous current mode (DCM), the ratio between the input voltage and current is only related to the duty cycle of the switch pulse width modulation signal. Using this property, the buck-boost converter can be used to perform semi-active vibration control by controlling the load connected between the terminals of the generator in the electromagnetic shock absorber. While performing the vibration control, the circuit always draw current from the shock absorber and the suspension remain dissipative, and the shock absorber takes no additional energy to perform the vibration control. The working principle and dynamics of the circuit has been analyzed and simulations were performed to validate the concept.

Li, Peng; Zhang, Chongxiao; Kim, Junyoung; Yu, Liangyao; Zuo, Lei

2014-04-01

129

Spectroscopic probes of vibrationally excited molecules at chemically significant energies

This project involves the application of multiple-resonance spectroscopic techniques for investigating energy transfer and dissociation dynamics of highly vibrationally excited molecules. Two major goals of this work are: (1) to provide information on potential energy surfaces of combustion related molecules at chemically significant energies, and (2) to test theoretical modes of unimolecular dissociation rates critically via quantum-state resolved measurements.

Rizzo, T.R. [Univ. of Rochester, NY (United States)

1993-12-01

130

NASA Technical Reports Server (NTRS)

Man's reactions to vibration are emphasized rather than his reactions to the vibrational characteristics of vehicles. Vibrational effects studies include: performance effects reflected in tracking proficiency, reaction time, visual impairment, and other measures related to man's ability to control a system; physiological reactions; biodynamic responses; subjective reactions; and human tolerance limits. Technological refinements in shaker systems and improved experimental designs are used to validate the data.

Hornick, R. J.

1973-01-01

131

Low Frequency Vibrational Spectra and Potential Energy Surface for Phthalan

The far-infrared and low-frequency Raman spectra of phthalan have been recorded and the ring-puckering and ring-flapping (butterfly) vibrations, which have fundemental frequencies of 31 and 216 cm -1, respectively, have been examined in detail. These two vibrations are strongly coupled, and this interaction results in complex spectra with numerous sum, difference and hot band series. A two-dimensional potential energy surface

Timothy Klots; Sachie Sakurai; Niklas Meinander; Jaan Laane

1996-01-01

132

Lower limbs power and stiffness after whole-body vibration.

The interest in whole-body vibration (WBV) for the enhancement of neuromuscular performance has received considerable attention. However, scientific evidence supporting the optimal prescription of WBV settings is lacking. This study investigated the acute effect of WBV combining high frequency/high peak-to-peak displacement (HH) or low frequency/low peak-to-peak displacement (LL) vs. sham intervention (SHAM) on lower limb muscle power and stiffness. A total of 223 volunteers were randomly assigned to either the HH, LL or SHAM group. Countermovement jump (CMJ) height, maximal and average power, maximal and average lower limbs stiffness obtained during a hopping test were recorded before and after the respective intervention. After the intervention, the HH group showed an increase of 4.64% in CMJ height (p<0.001) whereas the values of both the LL and SHAM groups did not change. In addition, maximal and average power of the lower limbs were significantly increased in all groups (p<0.001; 10.89% and 12.82%, respectively) while no effect on lower limbs stiffness was observed. Our data show that high frequency combined with high peak-to-peak displacement is the most optimal WBV setting for CMJ height enhancement. Further investigation should be undertaken to ascertain the effectiveness of WBV on lower limbs stiffness. PMID:23143701

Colson, S S; Petit, P-D

2013-04-01

133

NASA Technical Reports Server (NTRS)

A semiclassical collision model is applied to the study of energy transfer rates between a vibrationally excited diatomic molecule and a structureless atom. The molecule is modeled as an anharmonic oscillator with a multitude of dynamically coupled vibrational states. Three main aspects in the prediction of vibrational energy transfer rates are considered. The applicability of the semiclassical model to an anharmonic oscillator is first evaluated for collinear encounters. Second, the collinear semiclassical model is applied to obtain numerical predictions of the vibrational energy transfer rate dependence on the initial vibrational state quantum number. Thermally averaged vibration-translation rate coefficients are predicted and compared with CO-He experimental values for both ground and excited initial states. The numerical model is also used as a basis for evaluating several less complete but analytic models. Third, the role of rational motion in the dynamics of vibrational energy transfer is examined. A three-dimensional semiclassical collision model is constructed with coupled rotational motion included. Energy transfer within the molecule is shown to be dominated by vibration-rotation transitions with small changes in angular momentum. The rates of vibrational energy transfer in molecules with rational frequencies that are very small in comparison to their vibrational frequency are shown to be adequately treated by the preceding collinear models.

Mckenzie, R. L.

1976-01-01

134

NASA Astrophysics Data System (ADS)

In this letter, a single vibratory energy harvester integrated with an airfoil is proposed to concurrently harness energy from ambient vibrations and wind. In terms of its transduction capabilities and power density, the integrated device is shown to have a superior performance under the combined loading when compared to utilizing two separate devices to harvest energy independently from the two available energy sources. Even below its flutter speed, the proposed device was able to provide 2.5 times the power obtained using two separate harvesters.

Bibo, A.; Daqaq, M. F.

2013-06-01

135

Bottlenecks to vibrational energy flow in OCS: Structures and mechanisms

Finding the causes for the nonstatistical vibrational energy relaxation in the planar carbonyl sulfide (OCS) molecule is a longstanding problem in chemical physics: Not only is the relaxation incomplete long past the predicted statistical relaxation time, but it also consists of a sequence of abrupt transitions between long-lived regions of localized energy modes. We report on the phase space bottlenecks responsible for this slow and uneven vibrational energy flow in this Hamiltonian system with three degrees of freedom. They belong to a particular class of two-dimensional invariant tori which are organized around elliptic periodic orbits. We relate the trapping and transition mechanisms with the linear stability of these structures.

R. Paškauskas; C. Chandre; T. Uzer

2008-11-27

136

Quantum scattering calculations are reported for state-to-state vibrational relaxation and reactive scattering in O + OH(v = 2 ? 3, j = 0) collisions on the electronically adiabatic ground state {sup 2}A?? potential energy surface of the HO{sub 2} molecule. The time-independent Schrödinger equation in hyperspherical coordinates is solved to determine energy dependent probabilities and cross sections over collision energies ranging from ultracold to 0.35 eV and for total angular momentum quantum number J = 0. A J-shifting approximation is then used to compute initial state selected reactive rate coefficients in the temperature range T = 1 ? 400 K. Results are found to be in reasonable agreement with available quasiclassical trajectory calculations. Results indicate that rate coefficients for O{sub 2} formation increase with increasing the OH vibrational level except at low and ultralow temperatures where OH(v = 0) exhibits a slightly different trend. It is found that vibrational relaxation of OH in v = 2 and v = 3 vibrational levels is dominated by a multi-quantum process.

Pradhan, G. B.; Juanes-Marcos, J. C.; Balakrishnan, N., E-mail: naduvala@unlv.nevada.edu [Department of Chemistry, University of Nevada Las Vegas, Las Vegas, Nevada 89154 (United States); Kendrick, Brian K. [Theoretical Division (T-1, MS B221), Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)] [Theoretical Division (T-1, MS B221), Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

2013-11-21

137

NASA Astrophysics Data System (ADS)

Quantum scattering calculations are reported for state-to-state vibrational relaxation and reactive scattering in O + OH(v = 2 - 3, j = 0) collisions on the electronically adiabatic ground state 2A'' potential energy surface of the HO2 molecule. The time-independent Schrödinger equation in hyperspherical coordinates is solved to determine energy dependent probabilities and cross sections over collision energies ranging from ultracold to 0.35 eV and for total angular momentum quantum number J = 0. A J-shifting approximation is then used to compute initial state selected reactive rate coefficients in the temperature range T = 1 - 400 K. Results are found to be in reasonable agreement with available quasiclassical trajectory calculations. Results indicate that rate coefficients for O2 formation increase with increasing the OH vibrational level except at low and ultralow temperatures where OH(v = 0) exhibits a slightly different trend. It is found that vibrational relaxation of OH in v = 2 and v = 3 vibrational levels is dominated by a multi-quantum process.

Pradhan, G. B.; Juanes-Marcos, J. C.; Balakrishnan, N.; Kendrick, Brian K.

2013-11-01

138

NASA Astrophysics Data System (ADS)

Previous studies have quantified the power absorbed in the seated human body during exposure to vibration but have not investigated the effects of body posture or the power absorbed at the back and the feet. This study investigated the effects of support for the feet and back and the magnitude of vibration on the power absorbed during whole-body vertical vibration. Twelve subjects were exposed to four magnitudes (0.125, 0.25, 0.625, and 1.25 m s -2 rms) of random vertical vibration (0.25-20 Hz) while sitting on a rigid seat in four postures (feet hanging, maximum thigh contact, average thigh contact, and minimum thigh contact) both with and without a rigid vertical backrest. Force and acceleration were measured at the seat, the feet, and the backrest to calculate the power absorbed at these three locations. At all three interfaces (seat, feet, and back) the absorbed power increased in proportion to the square of the magnitude of vibration, with most power absorbed from vibration at the seat. Supporting the back with the backrest decreased the power absorbed at the seat at low frequencies but increased the power absorbed at high frequencies. Supporting the feet with the footrest reduced the total absorbed power at the seat, with greater reductions with higher footrests. It is concluded that contact between the thighs and the seat increases the power absorbed at the seat whereas a backrest can either increase or decrease the power absorbed at the seat.

Nawayseh, Naser; Griffin, Michael J.

2010-07-01

139

Absorption of Energy during Whole-Body Vibration Exposure

NASA Astrophysics Data System (ADS)

Absorbed power,PAbs, during exposure to vertical and horizontal whole-body vibration in sitting posture was measured using 15 male and 15 female subjects. Different experimental conditions were applied, such as vibration level (0·25-1·4 m/s2), frequency (1·13-80 Hz), body weight (54-93 kg), relaxed and erect upper body posture. Results show thatPAbswas strongly related to frequency of the vibration peaking, within the range of 4-6 Hz and below 2·5 Hz for vertical and horizontal directions respectively.PAbsincreased with acceleration level and body weight. If risk assessment is based on the assumption that the amount ofPAbs, independence of the frequency of the vibration, indicates a hazard, then the frequency weighting procedure in ISO-standard 2631 can be questioned. The ISO weighting for horizontal vibration seems to underestimate the risk for frequencies within the range of about 1·5-3 Hz and overestimate them above about 5 Hz. For the vertical direction the frequency weighting overestimates the risk for frequencies above about 6 Hz. The results also indicate a need for differential guidelines for females and males. Many types of vehicle produce whole-body vibration with frequencies in the range where the highestPAbswas observed. Although not yet thoroughly evaluated,PAbsmay be a better quantity for risk assessment than acceleration as specified in ISO 2631, since it also takes into account the dynamic force applied to the human body.

Lundström, R.; Holmlund, P.

1998-08-01

140

NASA Astrophysics Data System (ADS)

Power harvesters that extract energy from vibrating systems via piezoelectric transduction show strong potential for powering smart wireless sensor devices in applications of health condition monitoring of rotating machinery and structures. This paper presents an analytical method for modelling an electromechanical piezoelectric bimorph beam with tip mass under two input base transverse and longitudinal excitations. The Euler-Bernoulli beam equations were used to model the piezoelectric bimorph beam. The polarity-electric field of the piezoelectric element is excited by the strain field caused by base input excitation, resulting in electrical charge. The governing electromechanical dynamic equations were derived analytically using the weak form of the Hamiltonian principle to obtain the constitutive equations. Three constitutive electromechanical dynamic equations based on independent coefficients of virtual displacement vectors were formulated and then further modelled using the normalised Ritz eigenfunction series. The electromechanical formulations include both the series and parallel connections of the piezoelectric bimorph. The multi-mode frequency response functions (FRFs) under varying electrical load resistance were formulated using Laplace transformation for the multi-input mechanical vibrations to provide the multi-output dynamic displacement, velocity, voltage, current and power. The experimental and theoretical validations reduced for the single mode system were shown to provide reasonable predictions. The model results from polar base excitation for off-axis input motions were validated with experimental results showing the change to the electrical power frequency response amplitude as a function of excitation angle, with relevance for practical implementation.

Lumentut, M. F.; Howard, I. M.

2013-03-01

141

Does acute side-alternating vibration exercise enhance ballistic upper-body power?

The aim of this study was to investigate the effects of acute vibration exercise, at 2 different frequencies, on upper body power output. Muscle activity (EMG) and upper-body peak power was measured in 12 healthy males during ballistic bench press throws at 30% of 1-repetition maximum on a Smith machine. Measures were made prior to, 30?s and 5?min after one of 3 conditions performed for 30?s in a press-up position: side-alternating vibration at 20?Hz, 26?Hz and no vibration. EMG was recorded in the anterior deltoid, triceps brachii and pectoralis major during ballistic bench press throws as well as during application of each condition. While peak power output was higher at 5?min post condition across all conditions, compared to baseline measures (P<0.05), only 20?Hz vibration resulted in a significant increase in peak power output (P<0.05) compared to no vibration. EMG was greater during both vibration conditions, compared to no vibration (P<0.001). However, this difference was not evident during bench press throws when no difference was seen in muscle activity between conditions. These findings suggest that 20?Hz vibration has an ergogenic effect on upper-body power that may be due to peripheral, rather than central, mediated mechanisms. PMID:24838267

Cochrane, D J; Black, M J; Barnes, M J

2014-11-01

142

NASA Astrophysics Data System (ADS)

Based on the research results of conventional rigid support nonlinear energy harvesters, in this paper we conceive a kind of structure with an elastic support external magnet with the intent to keep the system in the state of bistable oscillation, even under low-intensity excitation conditions. It has been proved that elastic support systems have better power output performance than rigid support systems when excited at low-intensity vibrations. In addition, elastic support nonlinear energy harvesters do not need real-time adjustment of the magnet interval towards the variable-intensity random excitation source, consequently achieving maximum power output and sufficient electromechanical energy conversion of the system.

Gao, Y. J.; Leng, Y. G.; Fan, S. B.; Lai, Z. H.

2014-09-01

143

A two-dimensional broadband vibration energy harvester using magnetoelectric transducer

In this study, a magnetoelectric vibration energy harvester was demonstrated, which aims at addressing the limitations of the existing approaches in single dimensional operation with narrow working bandwidth. A circular cross-section cantilever rod, not a conventional thin cantilever beam, was adopted to extract vibration energy in arbitrary in-plane motion directions. The magnetic interaction not only resulted in a nonlinear motion of the rod with increased frequency bandwidth, but also contributed to a multi-mode motion to exhibit double power peaks. In energy harvesting with in-plane directions, it showed a maximum bandwidth of 4.4?Hz and power of 0.59?mW, with acceleration of 0.6?g (with g?=?9.8?m?s{sup ?2})

Yang, Jin, E-mail: yangjin@cqu.edu.cn; Wen, Yumei; Li, Ping; Yue, Xihai; Yu, Qiangmo; Bai, Xiaoling [Department of Optoelectronic Engineering, Research Center of Sensors and Instruments, Chongqing University, Chongqing 400044 (China)] [Department of Optoelectronic Engineering, Research Center of Sensors and Instruments, Chongqing University, Chongqing 400044 (China)

2013-12-09

144

Part I. It is shown that the most general potential energy function consistent with tetrahedral symmetry involves five force constants, also that with a suitable choice of variables this expression may be written in a quite simple form convenient for the discussion of different types of vibration. Special cases of potential energy such as the \\

Jenny E. Rosenthal

1934-01-01

145

NASA Astrophysics Data System (ADS)

Piezoelectric energy microgenerators are devices that continuously generate electricity when they are subjected to varying mechanical strain due to vibrations. They can generate electrical power up to 100 ?W which can be used to drive various sensing and actuating MEMS devices. Today, piezoelectric energy harvesters are considered autonomous and reliable energy sources to actuate low power microdevices such as wireless sensor networks, indoor-outdoor monitoring, facility management and biomedical applications. The advantages of piezoelectric energy harvesters including high power density, moderate output power and CMOS compatible fabrication in particular with aluminum nitride (AlN) have fuelled and motivated researchers to develop MEMS based energy harvesters. Recently, the use of AlN as a piezoelectric material has increased fabrication compatibility, enabling the realization of smart integrated systems on chip which include sensors, actuators and energy storage. Piezoelectric MEMS energy microgenerator is used to capture and transform the available ambient mechanical vibrations into usable electric energy via resonant coupling in the thin film piezoelectric material. Analysis and modeling of piezoelectric energy generators are very important aspects for improved performance. Aluminum nitride as the piezoelectric material is sandwiched between two electrodes. The device design includes a silicon cantilever on which the AlN film is deposited and which features a seismic mass at the end of the cantilever. Beam theory and lumped modeling with circuit elements are applied for modeling and analysis of the device operation at various acceleration values. The model shows good agreement with the experimental findings, thus giving confidence in the model.

Alamin Dow, Ali B.; Al-Rubaye, Hasan A.; Koo, David; Schneider, Michael; Bittner, Achim; Schmid, Ulrich; Kherani, Nazir P.

2011-06-01

146

Influence of Packing on Low Energy Vibrations of Densified Glasses

NASA Astrophysics Data System (ADS)

A comparative study of Raman scattering and low temperature specific heat capacity has been performed on samples of B2O3, which have been high-pressure quenched to go through different glassy phases having growing density to the crystalline state. It has revealed that the excess volume characterizing the glassy networks favors the formation of specific glassy structural units, the boroxol rings, which produce the boson peak, a broad band of low energy vibrational states. The decrease of boroxol rings with increasing pressure of synthesis is associated with the progressive depression of the excess low energy vibrations until their full disappearance in the crystalline phase, where the rings are missing. These observations prove that the additional soft vibrations in glasses arise from specific units whose formation is made possible by the poor atomic packing of the network.

Carini, Giovanni, Jr.; Carini, Giuseppe; D'Angelo, Giovanna; Tripodo, Gaspare; Di Marco, Gaetano; Vasi, Cirino; Gilioli, Edmondo

2013-12-01

147

Energy Measurement of Bubble Bursting Based on Vibration Signals

NASA Astrophysics Data System (ADS)

An experimental study of the energy of bubble bursting at the surface of a high-viscosity liquid on a cantilever beam is reported. The sudden bursting event of a bubble at the liquid surface can cause a vibration of the cantilever beam besides the acoustic wave and jet wave. The peaks of the vibration signal from the beam slightly lag the peaks of the acoustic signal, and the energy transferred to the vibration is larger than that transferred to the acoustic wave. The amplitude of the jet wave depends on the thickness of the liquid film and the size of the bubble. The results of the investigation can be used to understand the dynamic characteristics of bubble bursting.

Liu, Xiao-Bo; Zhang, Jian-Run; Li, Pu; Le, Van-Quynh

2012-06-01

148

High resolution (<1nm) interferometric fiber-optic sensor of vibrations in high-power transformers

A novel fiber-optic interferometric sensor is presented for vibrations measurements and analysis. In this approach, it is shown applied to the vibrations of electrical structures within power transformers. A main feature of the sensor is that an unambiguous optical phase measurement is performed using the direct detection of the interferometer output, without external modulation, for a more compact and stable

Jose A. Garcia-Souto; Horacio Lamela-Rivera

2006-01-01

149

A broadband vibrational energy harvester Louis Van Blarigan, Per Danzl, and Jeff Moehlisa)

A broadband vibrational energy harvester Louis Van Blarigan, Per Danzl, and Jeff Moehlisa for an energy harvester which has the potential to harvest vibrational energy over a broad range of ambient in the absence of vibrations. Experimental data show that this design allows enhanced harvesting of energy

Bigelow, Stephen

150

Absorption of energy during vertical whole-body vibration exposure.

Absorbed power (PAbs) during exposure to vertical whole-body vibration in a sitting posture was measured on 15 male and 15 female subjects. Different experimental conditions were applied, such as vibration level (0.5-1.4 m s(-2)) and frequency (2-100 Hz), body weight (54-93 kg) and, relaxed and erected upper body positions. Results show that PAbs was strongly related to the frequency of the vibration, peaking within the range of 4-6 Hz. The peak was predominantly located in the lower end of this range for females and for the relaxed sitting position. PAbs increased with acceleration level and body weight. Almost a ten-fold increase in PAbs was observed at the critical frequency when the vibration exposure was raised from 0.5 to 1.4 m s(-2). If risk assessment is based on the assumption that the amount of PAbs, independent of the frequency of the vibration, indicates a hazard, then the ISO-standard 2631 under- and overestimates the risk at frequencies below and above about 6 Hz, respectively. The results also indicate a need for differentiated guidelines for females and males. Many types of vehicles produce whole-body vibration with frequencies which coincide with the range where the highest PAbs was observed. PAbs is a 'new' concept for measurement of whole-body vibration exposure. Although not yet thoroughly evaluated, this measure may be a better quantity for risk assessment than those specified in ISO 2631 since it also takes the dynamic force applied to the human body into account. PMID:9672085

Lundström, R; Holmlund, P; Lindberg, L

1998-04-01

151

Design of a Step-Down AC-DC Converter for Energy Harvesting System Using Vibration-Based Energy

To realize battery-free operation employing energy harvesting, a step-down switched-capacitor-based converter has been used as a vibration-to-electricity converter. In this paper, to improve power efficiency, a step-down ACDC converter realizing 1\\/N (N=2,3,... ) conversion modes is designed by using switched-capacitor techniques. Although conventional converters offer an output by regulating the stored energy in a big capacitor, the proposed converter generates

Kei Eguchi; Sawai Pongswatd; Hirofumi Sasaki; Kitti Tirasesth; Tatsuya Sugimura; Takahiro Inoue

2009-01-01

152

NASA Astrophysics Data System (ADS)

Current theories of hegemony have, for the most part, ignored energy as a factor. It is argued here, however, that there are three reasons to expect energy to be a factor in the rise of nations to hegemonic power. First, societies require flow-throughs of energy, material, and information in order to maintain themselves, grow, and develop. Second, the types of energy systems used by a society set somewhat predictable limits on what humans can do and on how they will be organized. And third, since different energy sources and their associated technologies exhibit different capabilities and limitations, advantages may be conferred on one society over another based on the energy sources used by those societies. Case studies of the economic, military, and energy systems of the four nations that have achieved hegemony---Portugal, the Netherlands, the United Kingdom, and the United States---found that changes in energy systems were a significant factor in each instance of hegemony. Also examined was the premise that the rise and decline of hegemonic powers may reflect the movement away from, and subsequent return to, a condition of steady-state---where a society's energy systems, and those parts of the society that respond to changes in energy factors, change very slowly over time. It was postulated that an extended period of stable energy conditions in conjunction with the diffusion of technology would erode any energy-based differences in power among nations. While, on the other hand, the movement away from a condition of steady-state brought on by changes in a society's energy systems might provide that society with enough advantages that it could seek hegemony. Evidence for an association between the movement from one steady-state to another and the rise and decline of hegemony was found in only two of the four cases.

Hale, Cameron Edward

153

DEAP-based energy harvesting using vortex-induced vibrations

NASA Astrophysics Data System (ADS)

Generators based on dielectric electroactive polymers (DEAP) convert mechanical strain energy into electrical field energy. In order to harvest renewable energy from ambient sources adequate generator setups have to be developed. Thus, in this contribution a DEAP generator is presented which uses periodic vortex induced vibration of a circular cylinder as excitation mechanism, by which e.g. Flow energy of a wind or water current can be converted. For this purpose a novel generator design consisting of a cylinder that is elastically mounted on DEAP material is presented. Since the effect of vortex induced vibrations depends on the stiffness and damping of the utilized generator's eigenmode, a method to adapt both via the electrostatic pressure and energy conversion is proposed. After the validation of the general functionality of the novel generator design, analyses concerning the control of the overall harvester are carried out.

Hoffstadt, Thorben; Heinze, Robert; Wahl, Tim; Kameier, Frank; Maas, Jürgen

2014-03-01

154

Power flow analysis for amplifier design and energy harvesting

Power flow analysis for amplifier design and energy harvesting Nikola Vujica, Donald J. Leoa flow, state-space control, power harvesting, optimization 1. INTRODUCTION Active material systems on active and combined active and passive (hybrid) vibration suppression systems have shown a good

Lindner, Douglas K.

155

NASA Technical Reports Server (NTRS)

While the vibration analysis of gear systems has been developed, a systematic approach to the reduction of gearbox vibration has been lacking. The technique of reducing vibration by shifting natural frequencies is proposed here for gearboxes and other thin-plate structures using the theories of finite elements, modal analysis, and optimization. A triangular shell element with 18 degrees of freedom is developed for structural and dynamic analysis. To optimize, the overall vibration energy is adopted as the objective function to be minimized at the excitation frequency by varying the design variable (element thickness) under the constraint of overall constant weight. Modal analysis is used to determine the sensitivity of the vibration energy as a function of the eigenvalues and eigenvectors. The optimum design is found by the gradient projection method and a unidimensional search procedure. By applying the computer code to design problems for beams and plates, it was verified that the proposed method is effective in reducing vibration energy. The computer code is also applied to redesign the NASA Lewis gear noise rig test gearbox housing. As one example, only the shape of the top plate is varied, and the vibration energy levels of all the surfaces are reduced, yielding an overall reduction of 1/5 compared to the initial design. As a second example, the shapes of the top and two side plates are varied to yield an overall reduction in vibration energy of 1/30.

Inoue, Katsumi; Krantz, Timothy L.

1995-01-01

156

Originally Einstein proposed the the mass-energy equivalence at low speeds as E=mc^2 + 1\\/2 mv^2. However, a mass may also be rotating and vibrating as well as moving linearly. Although small, these kinetic energies must be included in formulating a true mathematical statement of the mass-energy equivalence. Also, gravitational, electromagneic and magnetic potential energies must be included in the mass-energy

Stewart Brekke

2010-01-01

157

NASA Astrophysics Data System (ADS)

Current commercial wireless tire pressure monitoring systems (TPMS) require a battery as electrical power source. The battery limits the lifetime of the TPMS. This limit can be circumvented by replacing the battery by a vibration energy harvester. Autonomous wireless TPMS powered by MEMS electret based vibration energy harvester have been demonstrated. A remaining technical challenge to attain the grade of commercial product with these autonomous TPMS is the mechanical reliability of the MEMS harvester. It should survive the harsh conditions imposed by the tire environment, particularly in terms of mechanical shocks. As shown in this article, our first generation of harvesters has a shock resilience of 400 g, which is far from being sufficient for the targeted application. In order to improve this aspect, several types of shock absorbing structures are investigated. With the best proposed solution, the shock resilience of the harvesters is brought above 2500 g.

Renaud, M.; Fujita, T.; Goedbloed, M.; de Nooijer, C.; van Schaijk, R.

2014-11-01

158

Skyrmion vibrational energies with a generalized mass term

We study various properties of a one parameter mass term for the Skyrme model, originating from the works of Kopeliovich, Piette and Zakrzewski, through the use of axially symmetric solutions obtained numerically by simulated-annealing. These solutions allow us to observe asymptotic behaviors of the B=2 binding energies that differ to those previously obtained. We also decipher the characteristics of three distinct vibrational modes that appear as eigenstates of the vibrational Hamiltonian. This analysis further examine the assertion that the one parameter mass term offers a better account of baryonic matter than the traditional mass term.

Merlin C. Davies; Luc Marleau

2009-04-21

159

Tunable Vibration Energy Harvester for Condition Monitoring of Maritime Gearboxes

NASA Astrophysics Data System (ADS)

This paper reports on a new tuning concept, which enables the operation of a vibration generator for energy autonomous condition monitoring of maritime gearboxes. The tuning concept incorporates a circular tuning magnet, which interacts with a coupling magnet attached to the active transducer element. The tuning range can be tailored to the application by careful design of the gap between tuning magnet and coupling magnet. A total rotation angle of only 180° is required for the tuning magnet in order to obtain the full frequency bandwidth. The tuning concept is successfully demonstrated by charging a 0.6 F capacitor on the basis of physical vibration profiles taken from a gearbox.

Hoffmann, D.; Willmann, A.; Folkmer, B.; Manoli, Y.

2014-11-01

160

Approaches to Measuring CO2(? 2)-O Vibrational Energy Transfer

NASA Astrophysics Data System (ADS)

Preliminary experiments have been carried out with the goal of accurately measuring the vibrational relaxation rate of CO2(? 2) by ground state atomic oxygen. Significant cooling occurs in the 70-120 km altitude region through efficient uppumping of vibrational ground state CO2 by ambient O atoms. Much of the nascently-excited CO2(? 2) radiatively decays, converting a portion of the ambient kinetic energy into 15 ? m IR emission which escapes into space. However, the rate constant for the reverse CO2(? 2)-O vibrational relaxation process is not generally agreed upon. In previous work, the rate constant was measured by photolyzing ozone in an O3-CO2-Ar mixture, both generating a high density of O atoms and slightly raising the gas temperature. The re-equilibration rate of the CO2 vibrational population was then monitored as a function of the O-atom density, using diode laser absorption in the 4.3 ? m region. In the present work, we are investigating a similar experiment utilizing the stable precursors NO2 and SO2 as alternatives to O3. We have also performed preliminary experiments in which the bend state of CO2 is selectively populated using stimulated Raman excitation. Finally, detection of the laser-excited CO2 vibrational populations has been performed using absorption of broadband IR radiation from a SiC lamp in conjunction with a Fourier transform spectrometer. We compare the advantages and disadvantages of using the FTIR technique versus diode laser detection.

Castle, K. J.; Hwang, E. S.; Dodd, J. A.

2001-12-01

161

NASA Astrophysics Data System (ADS)

Evaluation of human exposure whole-body vibration (WBV) and shock can be carried out in a variety of ways. The most commonly used standards for predicting discomfort from WBV are BS6841 (1987) and ISO2631-1 (1997) which offer different frequency weightings (Wband Wk) and three methods of assessment: vibration dose value (VDV), estimated VDV (eVDV) and maximum transient vibration value (MTVV). Previous studies have also used DRI and absorbed power for assessments of shock and WBV. This paper reports a laboratory study in which 24 human subjects were exposed to 15 vertical vibration stimuli comprising of random vibration, repeated shocks and combinations of random vibration and shocks at 0·5, 1·0 and 1·5 m/s2r.m.s. Subjects rated the discomfort from the vibration on a numerical scale after each exposure. Acquired acceleration signals were analyzed using VDV, r.m.s. and MTVV for unweighted,Wb , Wkand DRI weighted signals. Acceleration and force were combined to give a measure of absorbed power. Subjective responses were correlated to vibration magnitude for the 13 analysis types. VDV was the best standard method of assessment; MTVV was the worst. Wband Wkfrequency weightings showed slightly greater correlations between vibration magnitude and discomfort than DRI weighted or unweighted signals. For VDV, there were no significant differences between the correlations obtained using any frequency weighting. For assessment of all stimuli types together, absorbed power gave higher correlations with subjective discomfort than acceleration-based methods. It is concluded that the methods described in ISO2631-1 should be clarified and simplified. Due to the difficulty in measuring absorbed power in the field, methods proposed in BS6841 are recommended as the most appropriate for assessment of discomfort from continuous vibration or repeated shocks.

MANSFIELD, N. J.; HOLMLUND, P.; LUNDSTRÖM, R.

2000-02-01

162

Structural vibration control by synchronized switch damping energy transfer

NASA Astrophysics Data System (ADS)

The synchronized switch damping (SSD) technique has been demonstrated as an efficient means of suppressing structure vibrations. This paper presents a novel SSD technique based on an energy transfer (SSDET) scheme that transmits energy from an energy-source structure to a target structure in order to damp the latter. As a matter of fact, the transferred energy enhanced the synchronized switch damping on inductor (SSDI) with an initial current, thus leading to a better vibration control capability. The experiment, performed on a beam/plate system, succeeded in delivering an enhanced damping effect as compared to the SSDI technique by adopting the proposed control law. Comparisons between simulation and experiment also confirmed the effectiveness of the proposed mathematical model. The stability was discussed in order to determine the stability limit.

Li, Kaixiang; Gauthier, Jean-Yves; Guyomar, Daniel

2011-01-01

163

Vibration exposure for selected power hand tools used in automobile assembly.

A practical method for assessing vibration exposure for workers operating vibrating hand tools on an automobile assembly line is presented. Vibration exposure is difficult to assess directly using many fast Fourier transform (FFT) spectral analyzers because of long task cycle times. Exposure time cannot be accurately estimated using time standards because of the high variability between operators and work methods. Furthermore, because workers frequently move about and get into inaccessible spaces, it is difficult to record vibration without interfering with the operation. A work sampling method was used for determining vibration exposure time by attaching accelerometers to the tools and suspending a battery-operated digital data logger from the air hose. Vibration acceleration and frequency spectra for each tool were obtained off-line replicating actual working conditions and analyzed together with exposure time data for determining individual worker vibration exposure. Eight pneumatic vibrating power hand tools, representing tools commonly used in an automobile assembly plant, were studied. Spectra for the rotary and reciprocating power tools and had large distinct dominant fundamental frequencies occurring in a narrow frequency range between 35 Hz and 150 Hz. These frequencies corresponded closely to tool free-running speeds, suggesting that major spectral component frequencies may be predicted on the basis of speed for some tools. PMID:2220569

Radwin, R G; Armstrong, T J; Vanbergeijk, E

1990-09-01

164

A Branched Beam-Based Vibration Energy Harvester

NASA Astrophysics Data System (ADS)

In this paper, a strategy to utilize a branched beam system to improve the frequency response characteristic of vibration energy harvesting is demonstrated. A basic unit of the device consists of several branch beams with proof mass at their ends and one main cantilever beam with a piezoelectric component at its root and proof mass at its end. The device can utilize the resonance of the branch beams and main beam to generate multiple output voltage peaks, providing a better frequency response characteristic than that of the conventional piezoelectric vibration energy harvester. Multiple branch structure and multiple basic units with similar structures can be connected to generate more output voltage peaks in the frequency response characteristic. Only one piezoelectric component is needed in the device, which makes it competitive in the management of harvested electric energy.

Zhang, Guangcheng; Hu, Junhui

2014-09-01

165

A Branched Beam-Based Vibration Energy Harvester

NASA Astrophysics Data System (ADS)

In this paper, a strategy to utilize a branched beam system to improve the frequency response characteristic of vibration energy harvesting is demonstrated. A basic unit of the device consists of several branch beams with proof mass at their ends and one main cantilever beam with a piezoelectric component at its root and proof mass at its end. The device can utilize the resonance of the branch beams and main beam to generate multiple output voltage peaks, providing a better frequency response characteristic than that of the conventional piezoelectric vibration energy harvester. Multiple branch structure and multiple basic units with similar structures can be connected to generate more output voltage peaks in the frequency response characteristic. Only one piezoelectric component is needed in the device, which makes it competitive in the management of harvested electric energy.

Zhang, Guangcheng; Hu, Junhui

2014-11-01

166

Investigation of Vibrational Energy Transfer in Connected Structures

NASA Technical Reports Server (NTRS)

The results are reported of an analytical and experimental investigation on the vibrational energy transfer between connected substructures under random excitation. In the analytical area, the basic foundation and assumptions of the statistical energy analysis (SEA) method, a major tool in random response analysis of structures, were examined and reviewed. A new SEA formulation based on the strong coupling condition of the substructures was carried out and presented. Also presented were the results of vibration energy transfer study based on the wave equations applied to connected structures. In the experimental phase, three simple structural models were fabricated and tested. Additional tests were performed on selected substructures which formed parts of the test models. The test results were presented and evaluated against the analytical data.

Hwang, C.; Pi, W. S.

1973-01-01

167

NASA Astrophysics Data System (ADS)

This paper presents analytical modeling and case studies of broadband and band-limited random vibration energy harvesting using a piezoceramic patch attached on a thin plate. The literature of vibration-based energy harvesting has been mostly focused on resonant cantilevered structures. However, cantilevered beam-type harvesters have limited broadband vibration energy harvesting capabilities unless they are combined with a nonlinear component. Moreover, cantilever arrangements cannot always be mounted on thin structures (which are basic components of marine, aerospace, and ground transportation systems) without significantly affecting the host system's design and overall dynamics. A patch-based piezoelectric energy harvester structurally integrated to a thin plate can be a proper alternative to using resonant cantilevers for harvesting energy from thin structures. Besides, plate-like structures have more number of vibration modes compared to beam structures, offering better broadband performance characteristics. In this paper, we present analytical modelling of patch-based piezoelectric energy harvester attached on a thin plate for random vibrations. The analytical model is based on electromechanically-coupled distributed-parameter formulation and validated by comparing the electromechanical frequency response functions (FRFs) with experimental results. Example case studies are then presented to investigate the expected power output of a piezoceramic patch attached on an aluminum plate for the case of random force excitations. The effect of bandwidth of random excitation on the mean power and shunted mean-square vibration response are explored with a focus on the number of vibration modes covered in the frequency range of input power spectral density (PSD).

Aridogan, Ugur; Basdogan, Ipek; Erturk, Alper

2014-04-01

168

Vibrational energy relaxation of perylene in supercritical alcohols

NASA Astrophysics Data System (ADS)

The time resolved fluorescence spectra of perylene in sub- and supercritical methanol have been measured by using a streak camera in the lower-pressure region than 10 MPa and an optical Kerr gate spectroscopic method in the higher-pressure region than 10 MPa. The lineshape of the fluorescence spectrum has been found to be dependent on the time. By comparing the excess energy dependence of the fluorescence lineshape in vapour perylene without energy dissipation process, the spectral change was assigned to the vibrational energy relaxation process in the S1 state. The vibrational energy relaxation time at each solvent density in supercritical region was determined by the time-profile at the 0-0 band peak position in the fluorescence spectrum. The vibrational energy relaxation rate scaled by the square root of the temperature has been compared with the hydrogen-bonding degree between solvent molecules estimated by the NMR measurement (Hoffmann M M and Conradi M S 1998 J. Phys. Chem. B 102 263).

Kobayashi, I.; Nagao, S.; Terazima, M.; Kimura, Y.

2010-03-01

169

Investigation of folded spring structures for vibration-based piezoelectric energy harvesting

NASA Astrophysics Data System (ADS)

This paper presents a fixed-fixed folded spring as an alternative elastic element for beam-based piezoelectric energy harvesting. In order to harvest energy from low frequency vibration in an optimal manner, the natural/operational frequencies of harvesters must be reduced to match low frequency input vibrations. Therefore, natural frequency reduction of vibration-based energy harvesters is critical to maximize output power at low operational frequency. The mechanical optimization of cantilever-based piezoelectric energy harvesters is limited by residual stress-based beam curling that produced through microfabrication adding additional mechanical stiffness to the system. The fixed-fixed folded spring structure presented in this paper allows for increased effective beam length and residual stress relaxation, without out of plane beam curling to further reducing the natural frequency. Multiple designs of folded spring energy harvesters are presented to demonstrate the effect of important design parameters. It is shown that the folded spring harvesters were capable of harvesting electricity at low natural frequencies, ranging from 45?Hz to 3667?Hz. Additionally, the harvesters were shown to be insensitive to microfabrication-based residual stress beam curling. The maximum power output achieved by the folded spring harvesters was 690.5?nW at 226.3?Hz for a single harvesting element of an array, with a PZT layer thickness of 0.24??m. The work presented in this paper demonstrates that the fixed-fixed folded spring can be used as a viable structural element for low frequency piezoelectric energy harvesting to take advantage of ambient vibrations found in low frequency applications.

Lueke, J.; Rezaei, M.; Moussa, W. A.

2014-12-01

170

NASA Astrophysics Data System (ADS)

Basic research of MEMS based micro devices for vibration energy harvesting using vinylidene fluoride / trifluoroethylene (VDF/TrFE) copolymer thin film was investigated. The VDF/TrFE copolymer thin film was formed by spin coating. Thickness of VDF/TrFE copolymer thin film was ranged from 375 nm to 2793 nm. Impedance of VDF/TrFE copolymer thin film was measured by LCR meter. Thin film in each thickness was fully poled by voltage based on C-V characteristics result. Generated power of the devices under applied vibration was observed by an oscilloscope. When the film thickness is 2793 nm, the generated power was about 0.815 ?J.

Takiguchi, T.; Sasaki, T.; Nakajima, T.; Yamaura, S.; Sekiguchi, T.; Shoji, S.

2014-11-01

171

Analysis of Piezoelectric Materials for Energy Harvesting Devices under High-g Vibrations

NASA Astrophysics Data System (ADS)

We analyzed the miniaturized energy harvesting devices (each volume within 0.3 cm3) fabricated by using three types of piezoelectric materials such as lead zirconium titanate (PZT) ceramic, macro fiber composite (MFC) and poly(vinylidene fluoride) (PVDF) polymer to investigate the capability of converting mechanical vibration into electricity under larger vibration amplitudes or accelerations conditions (? 1g, gravitational acceleration). All prototypes based on a bimorph cantilever structure with a proof mass were aimed to operate at a vibration frequency of 100 Hz. PZT-based device was optimized and fabricated by considering the resonant frequency, the output power density, and the maximum operating acceleration or safety factor. PVDF- and MFC-prototypes were designed to have same resonant frequency as well as same volume of the piezoelectric materials as the PZT prototype. All three devices were measured to determine if they could generate enough power density to provide electric energy to power a wireless sensor or a microelectromechanical systems (MEMS) device without device failure.

Shen, Dongna; Choe, Song-Yul; Kim, Dong-Joo

2007-10-01

172

NASA Astrophysics Data System (ADS)

A magnetoelectric (ME) vibration energy harvester has been designed to scavenge sufficient energy from ambient vibration with arbitrary motion directions in a plane and over a range of frequencies. In the harvester, a circular-cross-section cantilever rod is adopted to extract the vibration energy due to its ability to host accelerations in arbitrary in-plane motion directions. The magnetic coupling between the magnet and the ME transducer results in nonlinear oscillation of the cantilever rod with increased frequency bandwidth. To achieve optimal vibration energy harvesting performance, the effects of the nonlinear vibration and the harvester parameters including the magnetic circuit and the separation distance on the electrical output and the?working bandwidth are analyzed. The experimental results show that the harvester can scavenge vibration energy in arbitrary in-plane directions, exhibiting a bandwidth of 4.0 Hz and maximum power of 0.22 mW at acceleration of 0.6 g (with g = 9.8 m s-2).

Yang, Jin; Wen, Yumei; Li, Ping; Yue, Xihai; Yu, Qiangmo

2014-07-01

173

Vibrational relaxation in clusters: Energy transfer in I2 ,,CO2...4 excited

Vibrational relaxation in clusters: Energy transfer in I2 Ã? ,,CO2...4 excited by femtosecond Vibrational relaxation dynamics in I2 (CO2)4 clusters are monitored by femtosecond stimulated emission pumping excite the I2 within the cluster with vibrational energies ranging from 0.57 to 0.86 eV; the subsequent

Neumark, Daniel M.

174

White Noise Responsiveness of an AlN Piezoelectric MEMS Cantilever Vibration Energy Harvester

NASA Astrophysics Data System (ADS)

This paper reports the design, analysis and experimental characterisation of a piezoelectric MEMS cantilever vibration energy harvester, the enhancement of its power output by adding various values of end mass, as well as assessing the responsiveness towards white noise. Devices are fabricated using a 0.5 ?m AlN on 10 ?m doped Si process. Cantilevers with 5 mm length and 2 mm width were tested at either unloaded condition (MC0: fn 577 Hz) or subjected to estimated end masses of 2 mg (MC2: fn 129 Hz) and 5 mg (MC5: fn 80 Hz). While MC0 was able to tolerate a higher drive acceleration prior to saturation (7 g with 0.7 ?W), MC5 exhibited higher peak power attainable at a lower input vibration (2.56 ?W at 3 ms?2). MC5 was also subjected to band-limited (10 Hz to 2 kHz) white noise vibration, where the power response was only a fraction of its resonant counterpart for the same input: peak instantaneous power >1 ?W was only attainable beyond 2 g of white noise, whereas single frequency resonant response only required 2.5 ms?2. Both the first resonant response and the band-limited white noise response were also compared to a numerical model, showing close agreements.

Jia, Y.; Seshia, A. A.

2014-11-01

175

Exploring the vibrational fingerprint of the electronic excitation energy via molecular dynamics

A Fourier-based method is presented to relate changes of the molecular structure during a molecular dynamics simulation with fluctuations in the electronic excitation energy. The method implies sampling of the ground state potential energy surface. Subsequently, the power spectrum of the velocities is compared with the power spectrum of the excitation energy computed using time-dependent density functional theory. Peaks in both spectra are compared, and motions exhibiting a linear or quadratic behavior can be distinguished. The quadratically active motions are mainly responsible for the changes in the excitation energy and hence cause shifts between the dynamic and static values of the spectral property. Moreover, information about the potential energy surface of various excited states can be obtained. The procedure is illustrated with three case studies. The first electronic excitation is explored in detail and dominant vibrational motions responsible for changes in the excitation energy are identified for ethylene, biphenyl, and hexamethylbenzene. The proposed method is also extended to other low-energy excitations. Finally, the vibrational fingerprint of the excitation energy of a more complex molecule, in particular the azo dye ethyl orange in a water environment, is analyzed.

Deyne, Andy Van Yperen-De; Pauwels, Ewald; Ghysels, An; Waroquier, Michel; Van Speybroeck, Veronique; Hemelsoet, Karen, E-mail: karen.hemelsoet@ugent.be [Center for Molecular Modeling (CMM), Ghent University, Technologiepark 903, 9052 Zwijnaarde (Belgium)] [Center for Molecular Modeling (CMM), Ghent University, Technologiepark 903, 9052 Zwijnaarde (Belgium); De Meyer, Thierry [Center for Molecular Modeling (CMM), Ghent University, Technologiepark 903, 9052 Zwijnaarde (Belgium) [Center for Molecular Modeling (CMM), Ghent University, Technologiepark 903, 9052 Zwijnaarde (Belgium); Department of Textiles, Ghent University, Technologiepark 907, 9052 Zwijnaarde (Belgium); De Clerck, Karen [Department of Textiles, Ghent University, Technologiepark 907, 9052 Zwijnaarde (Belgium)] [Department of Textiles, Ghent University, Technologiepark 907, 9052 Zwijnaarde (Belgium)

2014-04-07

176

Vibration energy harvesting via parametrically-induced bistability

NASA Astrophysics Data System (ADS)

The dynamic response to white Gaussian noise of a bistable non-linear vibration energy harvester based on the repulsive electrostatic interaction between a microcantilever and an electrode has been theoretically studied. The cantilever-electrode system can be brought from a linear regime characterized by a quadratic potential, when cantilever is far from the electrode, to a non-linear bistable regime characterized by a quartic potential, when both elements are close enough. This distance parameter, which is commonly used to tune bistability, is unusually used here also to inject the energy to the system in the form of displacement noise. Thus, the widening and shifting to the low-frequency region of the response spectrum as well as the enhancement of the rms out-of-plane vibration of the cantilever are both demonstrated through this parametrically-induced bistability.

Abadal, G.; López, M.; Venstra, W. J.; Murillo, G.; Torres, F.

2014-11-01

177

A review of vibration problems in power station boiler feed pumps

NASA Technical Reports Server (NTRS)

Boiler feed pump reliability and availability is recognized as important to the overall efficiency of power generation. Vibration monitoring is often used as a part of planned maintenance. This paper reviews a number of different types of boiler feed pump vibration problems describing some methods of solution in the process. It is hoped that this review may assist both designers and users faced with similar problems.

France, David

1994-01-01

178

An Active Micro Vibration Isolator with Zero-Power Controlled Magnetic Suspension Technology

In this paper, a three-degree-of-freedom vibration isolation system using active zero-power controlled magnetic suspension is presented in order to isolate vibrations transmitted from the ground and to attenuate the effect of direct disturbances on the table. The zero-compliance of the isolator for direct disturbances was realized by connecting a conventional mechanical spring in series with a negative spring produced by

Masaya Takasaki; Yuji Ishino; Hirohisa Suzuki; Takeshi Mizuno

2006-01-01

179

EFFECT OF MAGNITUDE OF VERTICAL WHOLE-BODY VIBRATION ON ABSORBED POWER FOR THE SEATED HUMAN BODY

The power absorbed by 12 male subjects during exposure to vertical whole-body vibration at six magnitudes of random vibration (0·25, 0·5, 1·0, 1·5, 2·0 and 2·5 ms?2r.m.s.) has been measured in the laboratory. All subjects showed greatest absorbed power at about 5 Hz, but the frequency of this peak in the absorbed power reduced with increasing vibration magnitude. The total

N. J. Mansfield; M. J. Griffin

1998-01-01

180

Conversion of ambient vibrational energy into electric power has been the impetus of much modern research. The traditional analysis has focused on absolute electrical power output from the harvesting devices and efficiency defined as the convertibility of an infinite resource of vibration excitation into power. This perspective has limited extensibility when applying resonant harvesters to host resonant structures when the inertial influence of the harvester is more significant. Instead, this work pursues a fundamental understanding of the coupled dynamics of a main mass-spring-damper system to which an electromagnetic or piezoelectric mass-spring-damper is attached. The governing equations are derived, a metric of efficiency is presented, and analysis is undertaken. It is found that electromagnetic energy harvesting efficiency and maximum power output is limited by the strength of the coupling such that no split system resonances are induced for a given mass ratio. For piezoelectric harvesters, only the coupling strength and certain design requirements dictate maximum power and efficiency achievable. Since the harvesting circuitry must "follow" the split resonances as the piezoelectric harvesters become more massive, the optimum design of piezoelectric harvesters appears to be more involved than for electromagnetic devices. PMID:22779465

Harne, Ryan L

2012-07-01

181

Electron-vibration energy exchange models in nitrogen-containing plasma flows

The physics of vibrational kinetics in nitrogen-containing plasma produced by collisions with electrons is studied on the basis of recently derived cross sections and rate coefficients for the resonant vibrational-excitation by electron-impact. The temporal relaxation of the vibrational energy and of the vibrational distribution function is analyzed in a state-to-state approach. The electron and vibrational temperatures are varied in the range [0-50 000] K. Conclusions are drawn with respect to the derivation of reduced models and to the accuracy of a relaxation time formalism. An analytical fit of the vibrational relaxation time is given.

Laporta, V. [Department of Physics and Astronomy, University College London, London WC1E 6BT (United Kingdom); Istituto di Metodologie Inorganiche e dei Plasmi, CNR, 70125 Bari (Italy); Bruno, D. [Istituto di Metodologie Inorganiche e dei Plasmi, CNR, 70125 Bari (Italy)

2013-03-14

182

Step-up converter for electromagnetic vibrational energy scavenger

This paper introduces a voltage multiplier (VM) circuit which can step up a minimum voltage of 150 mV (peak). The operation and characteristics of this converter circuit are described. The voltage multiplier circuit is also tested with micro and macro scale electromagnetic vibrational generators and the effect of the VM on the optimum load conditions of the electromagnetic generator is presented. The measured results show that 85% efficiency can be achieved from this VM circuit at a power level of 18 ?W.

Saha, C; Godsell, J; Carlioz, L; Wang, N; Mccloskey, P; Beeby, S; Tudor, J; Torah, Russel

2008-01-01

183

NASA Astrophysics Data System (ADS)

We present a low frequency vibration driven 2-DOF piezoelectric energy harvester with increased performance, in terms of both bandwidth and output power, by mechanical impact. It consists of two series spring-mass systems (positioned in a parallel manner) one of which responds to low frequency vibration, engages with the harvester base stopper periodically by piecewise linear impact, and transfers a secondary shock to the second spring- mass system comprising of power generating element. It introduces a non-linear frequency up- conversion mechanism which, in turn, generates increased output power within a wide range of applied frequency. A 2-DOF prototype harvester without stopper shows two narrow resonant peaks and delivers maximum 2.11?W peak power to its matched load resistance at 17Hz frequency and 0.5g acceleration. On the other hand, it offers a -3dB bandwidth of 15Hz (9Hz- 24Hz) and delivers maximum 202.4?W peak power to its matched load resistance at the same operating condition when a stopper is placed below the primary mass at 0.5mm distance. Generated power increases up to 449?W as the acceleration increases to 1g.

Halim, M. A.; Park, J. Y.

2014-11-01

184

Modeling and Tuning for Vibration Energy Harvesting using a Piezoelectric Bimorph

NASA Astrophysics Data System (ADS)

With the development of wireless sensors and other devices, the need for continuous power supply with high reliability is growing ever more. The traditional battery power supply has the disadvantage of limited duration of continuous power supply capability so that replacement for new batteries has to be done regularly. This can be quite inconvenient and sometimes quite difficult especially when the sensors are located in places not easily accessible such as the inside of a machine or wild field. This situation stimulates the development of renewable power supply which can harvest energy from the environment. The use of piezoelectric materials to converting environment vibration to electrical energy is one of the alternatives of which a broad range of research has been done by many researchers, focusing on different issues. The improvement of efficiency is one of the most important issues in vibration based energy harvesting. For this purpose different methods are devised and more accurate modeling of coupled piezoelectric mechanical systems is investigated. In the current paper, the research is focused on improving voltage generation of a piezoelectric bimorph on a vibration beam, as well as the analytical modeling of the same system. Also an initial study is conducted on the characteristics of the vibration of Zinc oxide (ZnO) nanowire, which is a promising material for its coupled semiconducting and piezoelectric properties. The effect on the voltage generation by different placement of the piezoelectric bimorph on the vibrating beam is investigated. The relation between the voltage output and the curvature is derived which is used to explain the effect of placement on voltage generation. The effect of adding a lumped mass on the modal frequencies of the beam and on the curvature distribution is investigated. The increased voltage output from the piezoelectric bimorph by using appropriately selected mass is proved analytically and also verified by experiment. For the modeling of piezoelectric generator, different methods are employed to modeling the coupled dynamics of a piezoelectric bimorph on a vibrating beam as well as a simple piezoelectric bimorph cantilever. The modeling of piezoelectric bimorph as an alternative current (AC) source with internal capacitance and resistance is used to analyze a piezoelectric bimorph cantilever and to calculate the optimal external load resistance for maximal power output. The couple dynamics method based on Hamilton's Principle is applied in the modeling of the piezoelectric bimorph on a vibrating beam. Impulse response experiment shows this method has a better estimation of the experimental results than the curvature model. The coupled dynamics model is also applied to piezoelectric bimorph cantilever and the external load resistance is also determined by this to maximize the power output. The finite element equations for the piezoelectric materials in the element domain are theoretically derived. The procedure of modeling a piezoelectric on a vibrating beam is demonstrated base on the package of ANSYS. The frequency response of ZnO nanowires with different dimensions is derived analytically for ambient mediums with different damping ratios. With help from nano research lab of Dr. Yong Zhu and the student Feng Xu, an experiment is conducted which indentifies the first modal frequency of ZnO nanowires with different dimensions. The experimental modal frequencies are compared with the numerical results. The influence of the thickness of deposit on the modal frequency is also investigated by finite element modeling.

Cao, Yongqing

185

Reaction of formaldehyde cation with methane: Effects of collision energy and methane vibrations

.1063/1.1577312 I. INTRODUCTION We report a study of the effects of collision energy (Ecol) and vibrational in progress. Vibrational mode effects probe dynamics in the early phase of a collision, before col- lisional synthesis in interstellar clouds,2Â4 where nonequilibrium conditions make vibrational effects important

Anderson, Scott L.

186

Field Telemetry of Blade-rotor Coupled Torsional Vibration at Matuura Power Station Number 1 Unit

NASA Technical Reports Server (NTRS)

The quasi-modal reduction technique and finite element model (FEM) were used to construct an analytical model for the blade-rotor coupled torsional vibration of a steam turbine generator of the Matuura Power Station. A single rotor test was executed in order to evaluate umbrella vibration characteristics. Based on the single rotor test results and the quasi-modal procedure, the total rotor system was analyzed to predict coupled torsional frequencies. Finally, field measurement of the vibration of the last stage buckets was made, which confirmed that the double synchronous resonance was 124.2 Hz, meaning that the machine can be safely operated. The measured eigen values are very close to the predicted value. The single rotor test and this analytical procedure thus proved to be a valid technique to estimate coupled torsional vibration.

Isii, Kuniyoshi; Murakami, Hideaki; Otawara, Yasuhiko; Okabe, Akira

1991-01-01

187

Quasisubharmonic vibrations in metal plates excited by high-power ultrasonic pulses

NASA Astrophysics Data System (ADS)

Strongly nonlinear vibration phenomena in metal plates excited by high-power ultrasonic pulses in different conditions are studied experimentally and theoretically. The experimental conditions for generating quasisubharmonics and subharmonics are found and discussed. The plate vibrations are characterized by waveforms, frequency spectra, pseudostate portraits, and Poincaré maps. Then, a three-degree-of-freedom vibroimpact-dynamic model is presented to explore the generation mechanisms of the quasisubharmonic and subharmonic vibrations in the plates. According to the model, the intermittent contact-impact forces caused by the interactions between the transducer horn tip and the plate are considered as the main source for generating the complex nonlinear vibration in the plate. The numerical calculation results can explain reasonably the observed experimental phenomena.

Chen, Zhao-jiang; Zhang, Shu-yi; Zheng, Kai; Kuo, Pao-kuang

2009-07-01

188

NASA Astrophysics Data System (ADS)

Harvesting energy from the surroundings has become a new trend in saving our environment. Among the established ones are solar panels, wind turbines and hydroelectric generators which have successfully grown in meeting the world's energy demand. However, for low powered electronic devices; especially when being placed in a remote area, micro scale energy harvesting is preferable. One of the popular methods is via vibration energy scavenging which converts mechanical energy (from vibration) to electrical energy by the effect of coupling between mechanical variables and electric or magnetic fields. As the voltage generated greatly depends on the geometry and size of the piezoelectric material, there is a need to define an optimum shape and configuration of the piezoelectric energy scavenger. In this research, mathematical derivations for unimorph piezoelectric energy harvester are presented. Simulation is done using MATLAB and COMSOL Multiphysics software to study the effect of varying the length and shape of the beam to the generated voltage. Experimental results comparing triangular and rectangular shaped piezoelectric beam are also presented.

Muthalif, Asan G. A.; Nordin, N. H. Diyana

2015-03-01

189

Piezoelectric energy harvesting devices for low frequency vibration applications

Energy harvesting, a process of capturing ambient waste energy and converting it into usable electricity, has been attracting more and more researchers' interest because of the limitations of traditional power sources, the increasing demands upon mobile devices such as wireless sensor networks, and the recent advent of the extremely low power electrical and mechanical devices such as microelectromechanical systems (MEMS).

Dongna Shen

2009-01-01

190

The delocalized, anticorrelated component of pigment vibrations can drive nonadiabatic electronic energy transfer in photosynthetic light-harvesting antennas. In femtosecond experiments, this energy transfer mechanism leads to excitation of delocalized, anticorrelated vibrational wavepackets on the ground electronic state that exhibit not only 2D spectroscopic signatures attributed to electronic coherence and oscillatory quantum energy transport but also a cross-peak asymmetry not previously explained by theory. A number of antennas have electronic energy gaps matching a pigment vibrational frequency with a small vibrational coordinate change on electronic excitation. Such photosynthetic energy transfer steps resemble molecular internal conversion through a nested intermolecular funnel. PMID:23267114

Tiwari, Vivek; Peters, William K.; Jonas, David M.

2013-01-01

191

The delocalized, anticorrelated component of pigment vibrations can drive nonadiabatic electronic energy transfer in photosynthetic light-harvesting antennas. In femtosecond experiments, this energy transfer mechanism leads to excitation of delocalized, anticorrelated vibrational wavepackets on the ground electronic state that exhibit not only 2D spectroscopic signatures attributed to electronic coherence and oscillatory quantum energy transport but also a cross-peak asymmetry not previously explained by theory. A number of antennas have electronic energy gaps matching a pigment vibrational frequency with a small vibrational coordinate change on electronic excitation. Such photosynthetic energy transfer steps resemble molecular internal conversion through a nested intermolecular funnel. PMID:23267114

Tiwari, Vivek; Peters, William K; Jonas, David M

2013-01-22

192

Novel optimized design of a piezoelectric energy harvester in a package for low amplitude vibrations

NASA Astrophysics Data System (ADS)

This paper presents a novel piezoelectric energy harvesting device created with the flip-chip bonding of two different parts, one is a MEMS die which plays the role of inertial mass and the other is an associate CMOS chip anchored to the vibrating environment. The flip-chip bonding is performed between the MEMS die, which consists of four piezoelectric beams connected to four PADs or anchor points, and a test PCB, which is used to validate the feasibility of the whole assembled system. The resulting system in package is a proof of concept of a novel design concept that increases the extracted power from an ambient vibration. FEM simulations have been carried out to study the mechanical behaviour of the who le system. Moreover, the fabrication of the piezoelectric die and the test PCB has been successfully performed, as well as their flip-chip integration.

Murillo, G.; Campanella, H.; Esteve, J.; Abadal, G.

2013-12-01

193

Active Vibration Control for Helicopter Interior Noise Reduction Using Power Minimization

NASA Technical Reports Server (NTRS)

This report describes work performed by United Technologies Research Center (UTRC) for NASA Langley Research Center (LaRC) under Contract NNL11AA06C. The objective of this program is to develop technology to reduce helicopter interior noise resulting from multiple gear meshing frequencies. A novel active vibration control approach called Minimum Actuation Power (MAP) is developed. MAP is an optimal control strategy that minimizes the total input power into a structure by monitoring and varying the input power of controlling sources. MAP control was implemented without explicit knowledge of the phasing and magnitude of the excitation sources by driving the real part of the input power from the controlling sources to zero. It is shown that this occurs when the total mechanical input power from the excitation and controlling sources is a minimum. MAP theory is developed for multiple excitation sources with arbitrary relative phasing for single or multiple discrete frequencies and controlled by a single or multiple controlling sources. Simulations and experimental results demonstrate the feasibility of MAP for structural vibration reduction of a realistic rotorcraft interior structure. MAP control resulted in significant average global vibration reduction of a single frequency and multiple frequency excitations with one controlling actuator. Simulations also demonstrate the potential effectiveness of the observed vibration reductions on interior radiated noise.

Mendoza, J.; Chevva, K.; Sun, F.; Blanc, A.; Kim, S. B.

2014-01-01

194

NASA Astrophysics Data System (ADS)

This paper presents an advanced study including the design, characterization and theoretical analysis of a capacitive vibration energy harvester. Although based on a resonant electromechanical device, it is intended for operation in a wide frequency band due to the combination of stop-end effects and a strong biasing electrical field. The electrostatic transducer has an interdigited comb geometry with in-plane motion, and is obtained through a simple batch process using two masks. A continuous conditioning circuit is used for the characterization of the transducer. A nonlinear model of the coupled system ‘transduce-conditioning circuit’ is presented and analyzed employing two different semi-analytical techniques together with precise numerical modelling. Experimental results are in good agreement with results obtained from numerical modelling. With the 1 g amplitude of harmonic external acceleration at atmospheric pressure, the system transducer-conditioning circuit has a half-power bandwidth of more than 30% and converts more than 2 µW of the power of input mechanical vibrations over the range of 140 and 160 Hz. The harvester has also been characterized under stochastic noise-like input vibrations.

Basset, P.; Galayko, D.; Cottone, F.; Guillemet, R.; Blokhina, E.; Marty, F.; Bourouina, T.

2014-03-01

195

The simulation results for electromagnetic energy harvesters (EMEHs) under broad band stationary Gaussian random excitations indicate the importance of both a high transformation factor and a high mechanical quality factor to achieve favourable mean power, mean square load voltage, and output spectral density. The optimum load is different for random vibrations and for sinusoidal vibration. Reducing the total damping ratio under band-limited random excitation yields a higher mean square load voltage. Reduced bandwidth resulting from decreased mechanical damping can be compensated by increasing the electrical damping (transformation factor) leading to a higher mean square load voltage and power. Nonlinear EMEHs with a Duffing spring and with linear plus cubic damping are modeled using the method of statistical linearization. These nonlinear EMEHs exhibit approximately linear behaviour under low levels of broadband stationary Gaussian random vibration; however, at higher levels of such excitation the central (resonant) frequency of the spectral density of the output voltage shifts due to the increased nonlinear stiffness and the bandwidth broadens slightly. Nonlinear EMEHs exhibit lower maximum output voltage and central frequency of the spectral density with nonlinear damping compared to linear damping. Stronger nonlinear damping yields broader bandwidths at stable resonant frequency. PMID:24605063

Khan, Farid; Stoeber, Boris; Sassani, Farrokh

2014-01-01

196

The simulation results for electromagnetic energy harvesters (EMEHs) under broad band stationary Gaussian random excitations indicate the importance of both a high transformation factor and a high mechanical quality factor to achieve favourable mean power, mean square load voltage, and output spectral density. The optimum load is different for random vibrations and for sinusoidal vibration. Reducing the total damping ratio under band-limited random excitation yields a higher mean square load voltage. Reduced bandwidth resulting from decreased mechanical damping can be compensated by increasing the electrical damping (transformation factor) leading to a higher mean square load voltage and power. Nonlinear EMEHs with a Duffing spring and with linear plus cubic damping are modeled using the method of statistical linearization. These nonlinear EMEHs exhibit approximately linear behaviour under low levels of broadband stationary Gaussian random vibration; however, at higher levels of such excitation the central (resonant) frequency of the spectral density of the output voltage shifts due to the increased nonlinear stiffness and the bandwidth broadens slightly. Nonlinear EMEHs exhibit lower maximum output voltage and central frequency of the spectral density with nonlinear damping compared to linear damping. Stronger nonlinear damping yields broader bandwidths at stable resonant frequency. PMID:24605063

Sassani, Farrokh

2014-01-01

197

NASA Astrophysics Data System (ADS)

Power harvesting techniques that convert vibration energy into electrical energy through piezoelectric transducers show strong potential for powering smart wireless sensor devices in applications of structural health monitoring. This paper presents an analytical model of the dynamic behavior of an electromechanical piezoelectric bimorph cantilever harvester connected with an AC-DC circuit based on the Euler-Bernoulli beam theory and Hamiltonian theorem. A new cantilevered piezoelectric bimorph structure is proposed in which the plug-type connection between support layer and tip-mass ensures that the gravity center of the tip-mass is collinear with the gravity center of the beam so that the brittle fracture of piezoelectric layers can also be avoided while vibrating with large amplitude. The tip-mass is equated by the inertial force and inertial moment acting at the end of the piezoelectric bimorph beam based on D'Alembert's principle. An AC-DC converting circuit soldered with the piezoelectric elements is also taken into account. A completely new analytic expression of the global behavior of the electromechanical piezoelectric bimorph harvesting system with AC-DC circuit under input base transverse excitation is derived. Moreover, an experimental energy harvester is fabricated and the theoretical analysis and experimental results of the piezoelectric harvester under the input base transverse displacement excitation are validated by using measurements of the absolute tip displacement, electric voltage response, electric current response and electric power harvesting.

Wang, Hongjin; Meng, Qingfeng

2013-03-01

198

Calculations of vibration-rotation energy levels of HD+

NASA Astrophysics Data System (ADS)

An artificial-channels scattering method [M. Shapiro and G. G. Balint-Kurti, J. Chem. Phys. 71, 1461 (1979)] is used with a transformed Hamiltonian [R. E. Moss and I. A. Sadler, Molec. Phys. 66, 591 (1989)] to calculate the energies of vibration-rotation levels for the ground electronic state of HD+. All nonadiabatic effects, except for part of the coupling of rotational and electronic angular momenta, are accounted for. The results, which are for v=0-21, J=0,1, together with some other levels involved in observed transitions, are compared with previous calculations, particularly those of Wolniewicz and Poll [Molec. Phys. 59, 953 (1986)]. Inclusion of a correction to the energies of J?0 levels to allow for the remaining contribution of ? electronic states permits comparison with experimental transition energies. The agreement is excellent.

Balint-Kurti, G. G.; Moss, R. E.; Sadler, I. A.; Shapiro, M.

1990-05-01

199

NASA Technical Reports Server (NTRS)

The vibration response of a gas-bearing rotor-support system was analyzed experimentally documented for sinusoidal and random vibration environments. The NASA Brayton Rotating Unit (BRU), 36,000 rpm; 10 KWe turbogenerator; was subjected in the laboratory to sinusoidal and random vibrations to evaluate the capability of the BRU to (1) survive the vibration levels expected to be encountered during periods of nonoperation and (2) operate satisfactorily (that is, without detrimental bearing surface contacts) at the vibration levels expected during normal BRU operation. Response power spectral density was calculated for specified input random excitation, with particular emphasis upon the dynamic motions of the thrust bearing runner and stator. A three-mass model with nonlinear representation of the engine isolator mounts was used to calculate axial rotor-bearing shock response.

Tessarzik, J. M.; Chiang, T.; Badgley, R. H.

1973-01-01

200

An evaluation on low-level vibration energy harvesting using piezoelectret foam

NASA Astrophysics Data System (ADS)

Energy harvesting technology is critical in the development of self-powered electronic devices. Over the past few decades, several transduction mechanisms have been investigated for harvesting various forms of ambient energy. This paper provides an investigation of a novel transducer material for vibration energy harvesting; piezoelectret foam. Piezoelectrets are cellular ferroelectret foams, which are thin, flexible polymeric materials that exhibit piezoelectric properties. The basic operational principle behind cellular ferroelectrets involves the deformation of internally charged voids in the polymer, which can be represented as macroscopic dipoles, resulting in a potential developed across the material. Both the mechanical and electromechanical properties of this material are investigated in this work. Mechanical testing is performed using traditional tensile testing techniques to obtain experimental measures of the stiffness and strength of the materials. Electromechanical testing is performed in order to establish a relationship between input mechanical energy and output electrical energy by dynamically measuring the piezoelectric constant, d33. Additionally, the properties of ferroelectret foams are compared to those of polyvinylidene fluoride (PVDF), a conventional polymer-based piezoelectric material whose crystalline phase exhibits piezoelectricity through dipole orientation. Finally, the feasibility of vibration energy harvesting using piezoelectret materials is investigated.

Anton, S. R.; Farinholt, K. M.

2012-04-01

201

A donor-acceptor pair for the real time study of vibrational energy transfer in proteins.

Vibrational energy transfer (VET) is believed to play an important role in protein function. Theoretical studies predict highly directional, anisotropic VET in proteins. Distinct energy transfer pathways which connect distant functional sites in proteins have been proposed by simulations, indicating a function in allosteric communication. Experimental evidence for such pathways, however, is lacking. In small molecules, ultrafast vibrational pump-probe spectroscopy has been used to investigate VET between different parts of a molecule in great detail. Here, we address the requirements for extending this powerful approach to proteins and present a protein-compatible donor-acceptor pair for the real time investigation of VET. This VET pair consists of two non-native amino acids, ?-(1-azulenyl)-alanine and azidohomoalanine, which can be positioned site-specifically and are found to be very well suited for spectroscopic studies of VET. Important for the study of proteins, co-translational incorporation of each of the amino acids has been demonstrated before using mutually independent approaches of protein engineering. We investigated the performance of the proposed VET pair in a model peptide which is designed to contain additional characteristic vibrational modes frequently used in infrared spectroscopy of proteins. Despite a larger inter-residue distance, we find that our VET acceptor generates a major signal that is easily observed compared to the other vibrational modes in the congested parts of the spectrum. We find sufficient signal size at concentrations compatible with proteins and over distances that will allow tracking of energy flow along predicted transfer pathways. PMID:24413252

Müller-Werkmeister, Henrike M; Bredenbeck, Jens

2014-02-21

202

Using powerful vibrators for calibration of seismic traces in nuclear explosion monitoring problems

NASA Astrophysics Data System (ADS)

The efficiency of functioning of the International Seismic Monitoring System (ISMS) is connected with the accuracy of the location and identification of a source of seismic waves which can be nuclear explosion. The errors in the determination of the location are caused by local and regional variations of wave hodographs. Empirical approach to solving these problems is to use events for which the locations and times are known, in order to determine a set of corrections to the regional model of wave propagation. The using of powerful vibrators for calibration of seismic traces is a new way in nuclear explosion monitoring problems. Now the 60-100 tons force vibrator can radiate the signals which can be recorded at the distances up to 500 km and can be used for regional calibration of seismic traces. The comparison of the seismic wave fields of powerful vibrators and 100-ton chemical explosion "Omega-3" at the 630-km profile, quarry explosions of the Kuznetsk basin with power from 50 to 700 tons at the distances up to 355 km showed their equivalence in the main types of waves. The paper presents the results of experiments of long-distance recording of seismic signals of powerful vibrators and detailed investigation of the velocity characteristics of the Earth's crust in West Siberia and Altay-Sayan region.

Glinsky, B.; Kovalevsky, V.; Seleznev, V.; Emanov, A.; Soloviev, V.

2009-04-01

203

Using powerful vibrators for calibration of seismic traces in nuclear explosion monitoring problems.

NASA Astrophysics Data System (ADS)

The efficiency of functioning of the International Seismic Monitoring System (ISMS) is connected with the accuracy of the location and identification of a source of seismic waves which can be nuclear explosion. The errors in the determination of the location are caused by local and regional variations of wave hodographs. Empirical approach to solving these problems is to use events for which the locations and times are known, in order to determine a set of corrections to the regional model of wave propagation. The using of powerful vibrators for calibration of seismic traces is a new way in nuclear explosion monitoring problems. Now the 60-100 tons force vibrator can radiate the signals which can be recorded at the distances up to 500 km and can be used for regional calibration of seismic traces. The comparison of the seismic wave fields of powerful vibrators and 100-ton chemical explosion "Omega-3" at the 630-km profile, quarry explosions of the Kuznetsk basin with power from 50 to 700 tons at the distances up to 355 km showed their equivalence in the main types of waves. The paper presents the results of experiments of long-distance recording of seismic signals of powerful vibrators and detailed investigation of the velocity characteristics of the Earth's crust in West Siberia and Altay-Sayan region.

Glinsky, B.; Kovalevsky, V.; Seleznev, V.; Emanov, A.; Soloviev, V.

2009-04-01

204

Determination of stepsize parameters for intermolecular vibrational energy transfer

Intermolecular energy transfer of highly excited polyatomic molecules plays an important role in many complex chemical systems: combustion, high temperature and atmospheric chemistry. By monitoring the relaxation of internal energy we have observed trends in the collisional efficiency ({beta}) for energy transfer as a function of the substrate's excitation energy and the complexities of substrate and deactivator. For a given substrate {beta} increases as the deactivator's mass increase to {approximately}30 amu and then exhibits a nearly constant value; this is due to a mass mismatch between the atoms of the colliders. In a homologous series of substrate molecules (C{sub 3}{minus}C{sub 8}) {beta} decreases as the number of atoms in the substrate increases; replacing F with H increases {beta}. All substrates, except for CF{sub 2}Cl{sub 2} and CF{sub 2}HCl below 10,000 cm{sup {minus}1}, exhibited that {beta} is independent of energy, i.e. <{Delta}E>{sub all} is linear with energy. The results are interpreted with a simple model which considers that {beta} is a function of the ocillators energy and its vibrational frequency. Limitations of current approximations used in high temperature unimolecular reactions were evaluated and better approximations were developed. The importance of energy transfer in product yields was observed for the photoactivation of perfluorocyclopropene and the photoproduction of difluoroethyne. 3 refs., 18 figs., 4 tabs.

Tardy, D.C.

1992-03-01

205

Energy 101: Concentrating Solar Power

From towers to dishes to linear mirrors to troughs, concentrating solar power (CSP) technologies reflect and collect solar heat to generate electricity. A single CSP plant can generate enough power for about 90,000 homes. This video explains what CSP is, how it works, and how systems like parabolic troughs produce renewable power. For more information on the Office of Energy Efficiency and Renewable Energy's CSP research, see the Solar Energy Technology Program's Concentrating Solar Power Web page at http://www1.eere.energy.gov/solar/csp_program.html.

None

2013-05-29

206

A micromachined low-frequency piezoelectric harvester for vibration and wind energy scavenging

NASA Astrophysics Data System (ADS)

To efficiently scavenge ambient vibration energy and wind energy at the same time, a low-frequency piezoelectric harvester was designed, fabricated and tested. A lumped-parameter model of the cantilevered piezoelectric energy harvester with a proof mass was established and the closed-form expressions of voltage and power on a resistance load under base acceleration excitation were derived. After effects of the lengths of the proof mass and electrodes on output power were analyzed, a MEMS harvester was optimally designed. By using aluminum nitride as piezoelectric layer, a MEMS energy harvester was fabricated with bulk micromachining process. Experimental results show that the open-circuit frequency of the MEMS harvester is about 134.8 Hz and the matched resistance is about 410 k?. Under the harmonic acceleration excitation of ±0.1 g, the maximum output power is about 1.85 µW, with the normalized power density of about 6.3 mW cm-3 g-2. The critical wind speed of the device is between 12.7 and 13.2 m s-1 when the wind direction is from the proof mass to the fixed end of the cantilever. The maximum output power under 16.3 m s-1 wind is about 2.27 µW.

He, Xuefeng; Shang, Zhengguo; Cheng, Yaoqing; Zhu, You

2013-12-01

207

NASA Astrophysics Data System (ADS)

This research work presents the design, fabrication and characterization of micromachined piezoelectric energy harvester stimulated by ambient random vibrations utilizing AlN as a piezoelectric material. The device design consists of a silicon cantilever beam on which AlN is sandwiched between two electrodes and a silicon seismic mass at the end of the cantilever beam. The generated electric power of the devices was experimentally measured at various acceleration levels. A maximum power of 34 ?W was obtained at an acceleration value of 2g for the device which measures 5.6 x 5.6 mm2. Various unpackaged devices were tested and assessed in terms of the generated power and resonant frequency at various acceleration values.

Alamin Dow, Ali B.; Bittner, Achim; Schmid, Ulrich; Kherani, Nazir P.

2013-05-01

208

Note: A cubic electromagnetic harvester that convert vibration energy from all directions.

We investigate the output performance of a cubic harvester which can scavenge low-frequency vibration energy from all directions. By adjusting the size and shape of the inside magnets, higher induced voltages and output power can be achieved. The optimal magnet is found to be cubic shape with the length of 6.35 mm (25.6% volume ratio), which can generate 4.27 mV root mean square voltage and 2.45 ?W average power at the frequency of 28.86 Hz and acceleration of 1.17 g. The device is also demonstrated as a self-powered tilt sensor by measuring induced voltages at different tilt angles. PMID:25085194

Han, Mengdi; Qiu, Guolin; Liu, Wen; Meng, Bo; Zhang, Xiao-Sheng; Zhang, Haixia

2014-07-01

209

Performance Evaluation of Vibration-Based Piezoelectric Energy Scavengers

. As a result, the foremost challenge for such dense networks to achieve their full potential is to manage power, ROC email: yichung@spring.iam.ntu.edu.tw S. Priya, D.J. Inman (eds.), Energy Harvesting Technologies

Shu, Yi-Chung

210

DSMC Modeling of Vibration-Vibration Energy Transfer Between Diatomic Molecules

Larsen-Borgnakke model, widely used in the DSMC method to simulate rotation-translation and vibration-translation exchanges in molecular collisions, is applied for the first time to resonant exchange between the vibrational modes of diatomic molecules (VV exchange). The validation of the model is performed through comparisons with experimental data on VV exchange in nitrogen.

Bondar, Ye. A.; Ivanov, M. S. [Khristianovich Institute of Theoretical and Applied Mechanics, Institutskaya 4/1, Novosibirsk 630090 (Russian Federation); Gimelshein, S. F. [University of Southern California, Los Angeles, CA 90089 (United States)

2008-12-31

211

Vibration excitation and energy transfer during ultrasonically assisted drilling

NASA Astrophysics Data System (ADS)

Successful application of ultrasonically assisted drilling needs dynamic matching of the transducer with the drill bit considered as a continuous system loaded by the nonlinear processing load. When using standard tools this leads to the compatible choice of the transducer and accurate matching of the transducer and tool. The principal dynamical features of this matching are considered. Optimal position of excitation cross section of the drill bit, which depends on the relationship between elasto-dissipative characteristics of the transducer, the drill bit and the work load, is found in general analytical form. The optimal matching preserves the resonant tuning of the transducer and compensates the additional energy losses in the drill bit and processing. This produces also an amplification of vibration amplitude. The effect is achieved through the generation and maintenance of a nonlinear resonant mode of vibration and by active matching of the oscillating system with the dynamic loads imposed by the cutting process with the help of the intelligent electronic feedback circuitry. A prototype of an ultrasonic drilling system has been designed, manufactured. and tested. Improvements of machining characteristics due to superposition of ultrasonic vibration are demonstrated. Substantial improvements in the cutting performance of drill bits lead to benefits in drilling performance, which include faster penetration rates, reduction of tool wear, improvements in the surface finish, roundness and straightness of holes and, in ductile materials, the reduction or even complete elimination of burrs on both the entrance and exit faces of plates. The reduction in the reactive force experienced also causes greatly reduced deformation when drilling through thin, flexible plates and helps to alleviate delamination hazard.

Babitsky, V. I.; Astashev, V. K.; Meadows, A.

2007-12-01

212

Laser power and energy measurements

Any laser system comprises a coherent source of radiation and a detector which responds to the temporal and\\/or spatial intensity variation of the radiation. Laser source and detector characterization necessary for design of laser systems is reviewed based on the concepts of radiant power and radiant energy to characterize instantaneous or average radiation. Measurement of total energy and average power

H. S. Boyne

1975-01-01

213

Probability-of-existence of vibro-impact regimes in a nonlinear vibration energy harvester

NASA Astrophysics Data System (ADS)

This paper reports on the characterization of high-energy vibro-impacting regimes in a vibration energy harvester with softening Duffing nonlinearity, by mathematical modelling and numerical analysis with experimental validation. The harvester is implemented as a base excited permanent-magnet/ball-bearing arrangement, where oscillations by the ball-bearing induce a change in magnetic flux in a wire coil, which in turn generates a voltage. Symmetric rigid aluminum stops in the harvester structure restrain the amplitude of the ball-bearing motion (within gap ?) and thus produce vibro-impact behaviour under certain operating conditions—leading to wideband operation. These operating conditions are analysed by means of an event-driven equation switching algorithm, implementing a base-driven Duffing oscillator with conditional hyster-Hertz impact mechanics. In considering the ‘probability-of-existence’ of impact regimes, predictions about the frequency bandwidth of the high-energy impact state are made and compared to the experimental prototype. A trade-off between operating bandwidth and output power is noted. For the non-optimized harvester arrangement examined in this paper, with a gap ? = 14.7 mm the bandwidth was predicted to be ˜1.3 Hz, and was measured at 0.7 Hz with an output power of 7.4 mW rms. With a gap size ? = 2.9 mm the bandwidth was predicted to be ˜7.2 Hz, and was measured at 6.1 Hz with an output power of 54 ?W rms. The authors believe that the probability-of-existence approach may be useful for characterizing the conditions required for exciting high-energy states of other nonlinear vibration energy harvesting systems.

Vandewater, L. A.; Moss, S. D.

2013-09-01

214

Vibrating Beam With Spatially Periodic Stiffness

NASA Technical Reports Server (NTRS)

Report presents theoretical analysis of vibrations of simply supported beam, bending stiffness varying about steady value, sinusoidally with position along length. Problem of practical importance because related to vibrations of twisted-pair electric-power transmission lines. Twists promote nonuniform shedding of vortexes and prevents resonant accumulation of vibrational energy from wind.

Townsend, John S.

1989-01-01

215

Enhanced vibration energy harvesting using dual-mass systems Xiudong Tang, Lei Zuo n

,7]. Because of its ubiquitous existence, vibration becomes a very promising alternative energy sourceEnhanced vibration energy harvesting using dual-mass systems Xiudong Tang, Lei Zuo n Department i n f o Article history: Received 1 September 2010 Received in revised form 16 May 2011 Accepted 17

Zuo, Lei

216

Vibration-assisted coherent excitation energy transfer in a detuning system

The roles of the vibration motions played in the excitation energy transfer process are studied. It is found that a strong coherent transfer in the hybrid system emerges when the detuning between the donor and the acceptor equals the intrinsic frequency of the vibrational mode, and as a result the energy can be transferred into the acceptor much effectively. Three cases of the donor and the acceptor coupling with vibrational modes are investigated respectively. We find that the quantum interference between the two different transfer channels via the vibrational modes can affects the dynamics of the system significantly.

Wang, Xin; Li, Hong-rong

2014-01-01

217

VIBRATING RF MEMS FOR LOW POWER WIRELESS COMMUNICATIONS

Micromechanical communication circuits fab- ricated via IC-compatible MEMS technologies and capable of low-loss filtering, mixing, switching, and frequency generation, are described with the intent to miniaturize wire- less transceivers. Possible transceiver front-end architectures are then presented that use these micromechanical circuits in large quantities to substantially reduce power consumption. Tech- nologies that integrate MEMS and transistor circuits into single-chip systems

Clark T.-C. Nguyen

218

Minimizing radiated sound power from vibrating shell structures: Theory and experiment

NASA Astrophysics Data System (ADS)

A new design methodology is presented here for finding optimal structural designs of shell structures for minimum sound power. Two optimization techniques are presented: the use of lumped masses and tuned absorbers. Thin shell structures were targeted for noise reduction because of their ubiquity in industry. They are used to cover and protect noisy devices, such as gearboxes and electrical transformers, and also to keep dirt and other contaminants away from moving parts, as in the case of automotive valve covers. The design strategy presented here involves three major computational tasks: predicting vibration of the structure, predicting the sound power created by the vibrating structure and finding optimal designs for minimum noise. A discrete Kirchhoff shell finite element is used to calculate vibration response, and a wave superposition boundary element method is used to calculate sound power. A combined gradient- based/stochastic optimization algorithm is used to find optimal lumped mass and absorber locations, as well as absorber design parameters (mass, stiffness and damping.) Three case studies are examined in this research: a flat plate, a half-cylindrical shell and a gearbox enclosure. Numerical and experimental results are presented for each study. It is shown that the optimization strategy presented here is capable of finding optimal designs which produce significant reductions in sound power in all three cases.

Constans, Eric William

1998-12-01

219

Vibration-to-electric energy conversion using a mechanically-varied capacitor

Past research in vibration energy harvesting has focused on the use of variable capacitors, magnets, or piezoelectric materials as the basis of energy transduction. How- ever, few of these studies have explored the detailed ...

Yen, Bernard Chih-Hsun, 1981-

2005-01-01

220

NASA Technical Reports Server (NTRS)

Brief ground tests were made to determine the effect of reduction of valve friction in a power control system of a fighter airplane by use of a vibrator. The vibrator was found to be an effective means of overcoming adverse effects of valve friction on the control characteristics.

Phillips, William H

1955-01-01

221

A fiber-optic interferometric sensor with intrinsic transducer along a length of the fiber is presented for vibration measurements of the magnetic core inside an oil-filled power transformer. The sensor is designed for high sensitivity measurements into the harsh environment of electromagnetic fields, wide temperature change, and in oil immersing. This sensor allows enough sensitivity for the application, for which vibrations

Horatio Lamela Rivera; Jose A. García-Souto; J. Sanz

2000-01-01

222

[Vibrational energy transfer from vibrational levels of RbH(X 1sigma+, v = 0-2) to H2].

The vibrational energy transfer from vibrational levels of RbH(X 1sigma+, v = 0-2) by collision with H2 was determined using the integrated time-resolved laser induced fluorescence (LIF) in a five-arm crossed heat-pipe oven. Rb-H2 mixture was irradiated with pulses of 696.4 nm radiation from a OPO laser, populating 6D state by two-photon absorption. The vibrational levels of RbH(X 1sigma+) generated in the reaction of Rb(6D) and H2 were detected by LIF technique. The nascent quantum state distributions of RbH were obtained when the delay time between the pump and probe laser was 20 ns. The nascent RbH product molecules were found to populate the lowest three vibrational (v = 0, 1, 2) levels of the ground electronic state but could not be detected in any higher vibrational state. The integrated time-resolved LIF excited A 1sigma+ --> X 1sigma+ system in the presence of H2 was recorded with delay time from 0 to 10 micros. The RbH signal of v = 0, 1 levels first increased and then decreased on a larger time scale. RbH was created instantaneously then was quenched by collision and diffused. The rate equations for the population of the vibrational levels were given. The integrated profiles method permitted us to determine the rate coefficients for vibrational transfer of RbH(X 1sigma+, v = 0-2) by collision with H2. The rate coefficients for collisional transfer of RbH(X 1sigma+) by collisions with H2 are (in units of 10-(11) cm3 x s(-1)) 3.4 +/- 0.8 and 2.8 +/- 0.6 for v = 2 --> v = 1 and v = 1 --> v = 0 respectively. The diffusion rates of v = 0, 1, 2 are (in units of 10(5) s(-1)) 4.9 +/- 1.1, 1.0 +/- 0.3 and 0.6 +/- 10.2, respectively. The experiment showed that vibrational relaxation from RbH(X 1sigma+, v = 0-2) was more efficient compared to that of other vibrational levels studied here. PMID:21428051

Shen, Xiao-Yan; Wang, Shu-Ying; Liu, Jing; Dai, Kang; Shen, Yi-Fan

2011-01-01

223

We consider the negative ion concentrations in hydrogen discharges caused by electron excitation and dissociative attachment processes. The principal formation and destruction processes are discussed for electron densities in the range 10/sup 8/ to 10/sup 13/ electrons cm/sup -3/. Expressions are developed for calculating the high energy portion of the electron energy distribution in the discharge; using these energy distributions the electron excitation rates are evaluated. At low densities, the vibrational distribution arises from singlet electronic excitations and triplet excitations through the /sup 3/..pi../sub u/ state, in equilibrium with wall de-excitation processes. At high densities singlet excitations predominate in equilibrium with atom-molecule de-excitation processes. Possibilities for negative ion generation in a two-chamber tandem system are discussed in which the vibrational excitation occurs in a high power, high electron temperature discharge, kT/sub e/ = 5 eV, and dissociative attachment occurs in a low temperature kT/sub e/ = 1 eV, plasma chamber.

Hiskes, J.R.; Karo, A.M.

1982-06-28

224

NASA Astrophysics Data System (ADS)

In this paper, the force analysis and output performance of the micro-vibration energy harvester are elaborated. The force of the floating magnet in the magnetic field of the lifting magnet is firstly analyzed. Using COMSOL™, the change of magnetic force exerted on the floating magnet versus the vertical distance and the horizontal eccentric distance is obtained for different lifting magnets of a cylinder, a ring and an inner cylinder plus an outer ring, respectively. When the distance between the lifting and floating magnets ranges from 7.3 to 8.1 mm, the change rate of the magnetic force versus the vertical distance for the inner cylinder plus outer ring structure is the smallest, whose value is 619 µN/mm. In other words, if the inner cylinder plus outer ring structure is used as the lifting magnet, the vibration space of the floating magnet is the largest, which is 8 and 7.6 % larger than the cylinder and ring lifting magnets, respectively. The horizontal restoring forces of the three structures are substantially equal to each other at the horizontal eccentric distance of 4 mm, which is around 860 µN. Then the equilibrium position change of the floating magnet is discussed when the energy harvester is in an inclined position. Finally, by the analysis of the vibration model, the output performances of the energy harvester are comparatively calculated under the vertical and inclined positions. At the natural frequency of 6.93 Hz, the maximum power of 66.7 µW is generated.

Ye, Zhitong; Duan, Zhiyong; Takahata, Kenichi; Su, Yufeng

2014-08-01

225

NASA Astrophysics Data System (ADS)

In this paper, the force analysis and output performance of the micro-vibration energy harvester are elaborated. The force of the floating magnet in the magnetic field of the lifting magnet is firstly analyzed. Using COMSOL™, the change of magnetic force exerted on the floating magnet versus the vertical distance and the horizontal eccentric distance is obtained for different lifting magnets of a cylinder, a ring and an inner cylinder plus an outer ring, respectively. When the distance between the lifting and floating magnets ranges from 7.3 to 8.1 mm, the change rate of the magnetic force versus the vertical distance for the inner cylinder plus outer ring structure is the smallest, whose value is 619 µN/mm. In other words, if the inner cylinder plus outer ring structure is used as the lifting magnet, the vibration space of the floating magnet is the largest, which is 8 and 7.6 % larger than the cylinder and ring lifting magnets, respectively. The horizontal restoring forces of the three structures are substantially equal to each other at the horizontal eccentric distance of 4 mm, which is around 860 µN. Then the equilibrium position change of the floating magnet is discussed when the energy harvester is in an inclined position. Finally, by the analysis of the vibration model, the output performances of the energy harvester are comparatively calculated under the vertical and inclined positions. At the natural frequency of 6.93 Hz, the maximum power of 66.7 µW is generated.

Ye, Zhitong; Duan, Zhiyong; Takahata, Kenichi; Su, Yufeng

2015-01-01

226

Vibrational Energy Coupling in Expanding N2/O2/NO Admixtures

NASA Technical Reports Server (NTRS)

Recent direct measurements of N2 and O2 vibrational populations in expansions of synthetic air show a closer coupling of the vibrational energies than indicated by adapting earlier experimental results from shock compressions to the nozzle expansion problem. An important difference between the shock wave and nozzle flow problems is the presence of NO in significant amounts throughout the relaxation in the case of a nozzle flow. This may account for the stronger coupling since NO is well suited to promote vibrational energy exchange. The results of a series of experiments and analysis examining vibrational energy coupling in expansions of admixtures approximating air are reported. N2 and O2 vibrational populations are determined by a single-pulse spontaneous Raman scattering technique. NO vibrational populations are determined by broadband absorption by the NO(y) system. The resulting data permit the role of NO in promoting vibrational energy coupling to be better understood, and are used to evaluate models of vibrational energy exchange for application to expanding flows.

Gilmore, John O.; Sharma, Surendra P.; Cavolowsky, John A. (Technical Monitor)

1995-01-01

227

NASA Astrophysics Data System (ADS)

Extensive research has been done on the topics of both turbulence-induced vibration and vibration based energy harvesting; however, little effort has been put into bringing these two topics together. Preliminary experimental studies have shown that piezoelectric structures excited by turbulent flow can produce significant amounts of useful power. This research could serve to benefit applications such as powering remote, self-sustained sensors in small rivers or air ventilation systems where turbulent fluid flow is a primary source of ambient energy. A novel solution for harvesting energy in these unpredictable fluid flow environments was explored by the authors in previous work, and a harvester prototype was developed. This prototype, called piezoelectric grass, has been the focus of many experimental studies. In this paper the authors present a theoretical analysis of the piezoelectric grass harvester modeled as a single unimorph cantilever beam exposed to turbulent cross-flow. This distributed parameter model was developed using a combination of both analytical and statistical techniques. The analytical portion uses a Rayleigh–Ritz approximation method to describe the beam dynamics, and utilizes piezoelectric constitutive relationships to define the electromechanical coupling effects. The statistical portion of the model defines the turbulence-induced forcing function distributed across the beam surface. The model presented in this paper was validated using results from several experimental case studies. Preliminary results show that the model agrees quite well with experimental data. A parameter optimization study was performed with the proposed model. This study demonstrated how a new harvester could be designed to achieve maximum power output in a given turbulent fluid flow environment.

Hobeck, J. D.; Inman, D. J.

2014-11-01

228

NSDL National Science Digital Library

Have you ever wondered how energy changes from one form to another? How you can put food in microwave, and seconds later it is hot? What happens between the time you plug in a TV and you see a picture? Students will take a deeper look into energy. What are all of the kinds of energy that help an object work? This lesson is a fun way to involve kids in their learning and include technology to present.

Diana Congden

2012-06-14

229

Piezoelectric Vibrational Energy Harvester Using Lead-Free Ferroelectric BiFeO3 Films

NASA Astrophysics Data System (ADS)

We have proposed that BiFeO3 films are suitable for piezoelectric vibrational energy harvester (VEH) applications, because BiFeO3 has high spontaneous polarization and low dielectric permittivity. We demonstrated that energy can be harvested by a micromachined VEH using a BiFeO3 film deposited using a sol-gel process. A VEH with a resonant frequency of ˜98 Hz produced an output voltage of 1.5 V·G-1 and electrical power of 2.8 µW·mm-3·G-2 (G=9.8 m/s2) at a load resistance of 1 M?. Using the analytical model for VEH, the generalized electromechanical coupling factor was estimated to be 0.41%. These results were comparable to those of the best-performing VEHs using other piezoelectric films.

Yoshimura, Takeshi; Murakami, Shuichi; Wakazono, Keisuke; Kariya, Kento; Fujimura, Norifumi

2013-05-01

230

Reliability of vibration energy harvesters of metal-based PZT thin films

NASA Astrophysics Data System (ADS)

This paper describes the reliability of piezoelectric vibration energy harvesters (PVEHs) of Pb(Zr,Ti)O3 (PZT) thin films on metal foil cantilevers. The PZT thin films were directly deposited onto the Pt-coated stainless-steel (SS430) cantilevers by rf-magnetron sputtering, and we observed their aging behavior of power generation characteristics under the resonance vibration condition for three days. During the aging measurement, there was neither fatigue failure nor degradation of dielectric properties in our PVEHs (length: 13 mm, width: 5.0 mm, thickness: 104 ?m) even under a large excitation acceleration of 25 m/s2. However, we observed clear degradation of the generated electric voltage depending on excitation acceleration. The decay rate of the output voltage was 5% from the start of the measurement at 25 m/s2. The transverse piezoelectric coefficient (e31,f) also degraded with almost the same decay rate as that of the output voltage; this indicates that the degradation of output voltage was mainly caused by that of piezoelectric properties. From the decay curves, the output powers are estimated to degrade 7% at 15 m/s2 and 36% at 25 m/s2 if we continue to excite the PVEHs for 30 years.

Tsujiura, Y.; Suwa, E.; Kurokawa, F.; Hida, H.; Kanno, I.

2014-11-01

231

NASA Astrophysics Data System (ADS)

We have presented a frequency up-converted hybrid type (Piezoelectric and Electromagnetic) vibration energy harvester that can be used in powering portable and wearable smart devices by handy motion. A transverse impact mechanism has been employed for frequency up-conversion. Use of two transduction mechanisms increases the output power as well as power density. The proposed device consists of a non-magnetic spherical ball (freely movable at handy motion frequency) to impact periodically on the parabolic top of a piezoelectric (PZT) cantilevered mass by sliding over it, allowing it to vibrate at its higher resonant frequency and generates voltage by virtue of piezoelectric effect. A magnet attached to the cantilever vibrates along with it at the same frequency and a relative motion between the magnet and a coil placed below it, induces emf voltage across the coil terminals as well. A macro-scale prototype of the harvester has been fabricated and tested by handy motion. With an optimum magnet-coil overlap, a maximum 0.98mW and 0.64mW peak powers have been obtained from the piezoelectric and the electromagnetic transducers of the proposed device while shaken, respectively. It offers 84.4?Wcm?3 peak power density.

Halim, M. A.; Cho, H. O.; Park, J. Y.

2014-11-01

232

. As California seeks to expand solar and wind power, storage of that energy for use at any time, day or night pumping water uphill overnight, when demand is low and electricity is cheap, and then releasing

Sadoulet, Elisabeth

233

NASA Astrophysics Data System (ADS)

Micro-fabricated piezoelectric vibration energy harvesters with resonance frequencies of 31-232 Hz are characterized and deployed for testing on ambient vibration sources in the machine room of a large building. A survey of 23 ambient vibration sources in the machine room is presented. A model is developed which uses a discretization method to accept measured arbitrary acceleration data as an input and gives harvester response as output. The modeled and measured output from the energy harvesters is compared for both vibrometer and ambient vibration sources. The energy harvesters produced up to 43 nWrms g-2 on a laboratory vibrometer and 10 nW g-2 on ambient vibration sources typically in large buildings.

Miller, L. M.; Halvorsen, E.; Dong, T.; Wright, P. K.

2011-04-01

234

ERIC Educational Resources Information Center

The demand of Americans for more and more power, particularly electric power, contrasted by the deep and growing concern for the environment and a desire by private citizens to participate in the public decisions that affect the environment is the dilemma explored in this book. Part One by John Holdren, offers a scientist's overview of the energy…

Holdren, John; Herrera, Philip

235

Energy harvesting and vibration control using piezoelectric elements and a nonlinear approach

The piezoelectric materials, as the most widely used functional materials in smart structures, have many outstanding advantages for sensors and actuators, especially in vibration control and energy harvesting, because of their excellent mechanical-electrical coupling characteristics and frequency response characteristics. Semi-active vibration control based on state switching and pulse switching, have been receiving much attention over the past decade because of

J. H. Qiu; H. L. Ji; H. Shen

2009-01-01

236

The vibrational energy dissipation process of the ground-state azulene in supercritical xenon, carbon dioxide, and ethane has been studied by the transient grating spectroscopy. In this method, azulene in these fluids was photoexcited by two counterpropagating subpicosecond laser pulses at 570 nm, which created a sinusoidal pattern of vibrationally hot ground-state azulene inside the fluids. The photoacoustic signal produced by the temperature rise of the solvent due to the vibrational energy relaxation of azulene was monitored by the diffraction of a probe pulse. The temperature-rise time constants of the solvents were determined at 383 and 298 K from 0.7 to 2.4 in rho(r), where rho(r) is the reduced density by the critical density of the fluids, by the fitting of the acoustic signal based on a theoretical model equation. In xenon, the temperature-rise time constant was almost similar to the vibrational energy-relaxation time constant of the photoexcited solute determined by the transient absorption measurement [D. Schwarzer, J. Troe, M. Votsmeier, and M. Zerezke, J. Chem. Phys. 105, 3121 (1996)] at the same reduced density irrespective of the solvent temperature. On the other hand, the temperature-rise time constants in ethane were larger than the vibrational energy-relaxation time constants by a factor of about 2. In carbon dioxide, the difference was small. From these results, the larger time constants of the solvent temperature rise than those of the vibrational energy relaxation in ethane and carbon dioxide were interpreted in terms of the vibrational-vibrational (V-V) energy transfer between azulene and solvent molecules and the vibrational-translational (V-T) energy transfer between solvent molecules. The contribution of the V-V energy transfer process against the V-T energy transfer process has been discussed. PMID:16108674

Kimura, Y; Yamamoto, Y; Fujiwara, H; Terazima, M

2005-08-01

237

Harvesting broadband kinetic impact energy from mechanical triggering/vibration and water waves.

We invented a triboelectric nanogenerator (TENG) that is based on a wavy-structured Cu-Kapton-Cu film sandwiched between two flat nanostructured PTFE films for harvesting energy due to mechanical vibration/impacting/compressing using the triboelectrification effect. This structure design allows the TENG to be self-restorable after impact without the use of extra springs and converts direct impact into lateral sliding, which is proved to be a much more efficient friction mode for energy harvesting. The working mechanism has been elaborated using the capacitor model and finite-element simulation. Vibrational energy from 5 to 500 Hz has been harvested, and the generator's resonance frequency was determined to be ?100 Hz at a broad full width at half-maximum of over 100 Hz, producing an open-circuit voltage of up to 72 V, a short-circuit current of up to 32 ?A, and a peak power density of 0.4 W/m(2). Most importantly, the wavy structure of the TENG can be easily packaged for harvesting the impact energy from water waves, clearly establishing the principle for ocean wave energy harvesting. Considering the advantages of TENGs, such as cost-effectiveness, light weight, and easy scalability, this approach might open the possibility for obtaining green and sustainable energy from the ocean using nanostructured materials. Lastly, different ways of agitating water were studied to trigger the packaged TENG. By analyzing the output signals and their corresponding fast Fourier transform spectra, three ways of agitation were evidently distinguished from each other, demonstrating the potential of the TENG for hydrological analysis. PMID:24964297

Wen, Xiaonan; Yang, Weiqing; Jing, Qingshen; Wang, Zhong Lin

2014-07-22

238

Dynamical traps lead to the slowing down of intramolecular vibrational energy flow.

The phenomenon of intramolecular vibrational energy redistribution (IVR) is at the heart of chemical reaction dynamics. Statistical rate theories, assuming instantaneous IVR, predict exponential decay of the population with the properties of the transition state essentially determining the mechanism. However, there is growing evidence that IVR competes with the reaction timescales, resulting in deviations from the exponential rate law. Dynamics cannot be ignored in such cases for understanding the reaction mechanisms. Significant insights in this context have come from the state space model of IVR, which predicts power law behavior for the rates with the power law exponent, an effective state space dimensionality, being a measure of the nature and extent of the IVR dynamics. However, whether the effective IVR dimensionality can vary with time and whether the mechanism for the variation is of purely quantum or classical origins are issues that remain unresolved. Such multiple power law scalings can lead to surprising mode specificity in the system, even above the threshold for facile IVR. In this work, choosing the well-studied thiophosgene molecule as an example, we establish the anisotropic and anomalous nature of the quantum IVR dynamics and show that multiple power law scalings do manifest in the system. More importantly, we show that the mechanism of the observed multiple power law scaling has classical origins due to a combination of trapping near resonance junctions in the network of classical nonlinear resonances at short to intermediate times and the influence of weak higher-order resonances at relatively longer times. PMID:25246538

Manikandan, Paranjothy; Keshavamurthy, Srihari

2014-10-01

239

Origin of Low-Energy Quadrupole Collectivity in Vibrational Nuclei H. Fujita,2,3

Origin of Low-Energy Quadrupole Collectivity in Vibrational Nuclei C. Walz,1 H. Fujita,2,3 A is a separation of energy (respectively momentum) scales such that the high-energy degrees of freedom) energy scale. In the IBM the relevant low-energy degrees of freedom for the description of quadrupole

Ponomarev, Vladimir

240

Vibration Exercise as a Warm-up Modality for Deadlift Power Output.

Vibration exercise (VbX) has gained popularity as a warm-up modality to enhance performance in golf, baseball and sprint cycling but little is known about the efficacy of using VbX as a warm-up prior to resistance exercise, such as deadlifting. The aim of this study was to compare the effects of a deadlift (DL) specific warm-up, VbX warm-up and Control on DL power output. The DL warm-up included 10, 8, and 5 repetitions performed at 30%, 40%, and 50% 1 repetition maximum (RM), respectively, where the number of repetitions was matched by body weight squats performed with vibration and without vibration (Control). The warm-up conditions were randomised and performed at least 2 days apart. Peak power, mean power, rate of force development, and electromyography (EMG) were measured during the concentric phase of two consecutive deadlifts (75% 1 RM) at 30 s and 2:30 min following the warm-up conditions. There was no significant (p > 0.05) main effect or interaction effect between the DL warm-up, VbX warm-up and Control for peak power, mean power, rate of force development, and EMG. VbX warm-up did not exhibit an ergogenic effect to potentiate muscle activity more than the specific deadlift warm-up and Control. Therefore, DL PO is affected to a similar extent, irrespective of the type of stimuli, when the warm-up is not focused on raising muscle temperature. PMID:25353078

Cochrane, Darryl J; Coley, Karl W; Pritchard, Hayden J; Barnes, Matthew J

2014-10-28

241

Effect of Magnitude of Vertical Whole-Body Vibration on Absorbed Power for the Seated Human Body

NASA Astrophysics Data System (ADS)

The power absorbed by 12 male subjects during exposure to vertical whole-body vibration at six magnitudes of random vibration (0·25, 0·5, 1·0, 1·5, 2·0 and 2·5 ms-2r.m.s.) has been measured in the laboratory. All subjects showed greatest absorbed power at about 5 Hz, but the frequency of this peak in the absorbed power reduced with increasing vibration magnitude. The total absorbed power increased approximately in proportion to the square of the acceleration magnitude: normalizing the absorbed power to the square of the r.m.s. vibration magnitude removed most of the differences, although the changes in resonance frequency were still evident. The frequency dependence of absorbed power at a constant magnitude of acceleration was approximated by a simple weighting having slopes of ±6 dB/octave either side of 5 Hz. Comparing the characteristics of this absorbed power weighting to standard frequency weightings showed substantial differences, especially at high frequencies. It is concluded that the differences from currently accepted frequency weightings are so great that the absorbed power is unlikely to yield good general predictions of the discomfort or risks of injury from whole-body vertical vibration.

Mansfield, N. J.; Griffin, M. J.

1998-08-01

242

Inclusion of nonadiabiatic effects in calculations on vibrational excitation of molecular hydrogen September 1998 The nonadiabatic phase matrix method offers a unified, systematic treatment of vibrational fully adiabatic counterpart, the energy-modified adiabatic method--includes nonadiabatic effects, which

Morrison, Michael A.

243

NASA Technical Reports Server (NTRS)

A semiclassical model of the inelastic collision between a vibrationally excited anharmonic oscillator and a structureless atom was used to predict the variation of thermally averaged vibration-translation rate coefficients with temperature and initial-state quantum number. Multiple oscillator states were included in a numerical solution for collinear encounters. The results are compared with CO-He experimental values for both ground and excited initial states using several simplified forms of the interaction potential. The numerical model was also used as a basis for evaluating several less complete but analytic models. Two computationally simple analytic approximations were found that successfully reproduced the numerical rate coefficients for a wide range of molecular properties and collision partners. Their limitations were also identified. The relative rates of multiple-quantum transitions from excited states were evaluated for several molecular types.

Mckenzie, R. L.

1975-01-01

244

NASA Astrophysics Data System (ADS)

The need for reduced power requirements for small electronic components, such as wireless sensor networks, has prompted interest in recent years for energy harvesting technologies capable of capturing energy from broadband ambient vibrations. Encouraging results have been reported for an arrangement of piezoelectric layers attached to carbon fiber / epoxy laminates which possess bistability by virtue of their specific asymmetric stacking sequence. The inherent bistability of the underlying structure is exploited for energy harvesting since a transition from one stable configuration to another, or `snap-through', is used to repeatedly strain the surface-bonded piezoelectric and generate electrical energy. Existing studies, both experimental and modelling, have been limited to simple geometric laminate shapes, restricting the scope for improved energy harvesting performance by limiting the number of design variables. In this paper we present an analytical model to predict the static shapes of laminates of any desired profile, validated experimentally using a digital image correlation system. Good accuracy in terms of out-of-plane displacements (5-7%) are shown in line with existing square modelling results. The static model is then mapped to a dynamics model and used to compare results against an experimental study of the harvesting performance of an example arbitrary geometry piezoelectric-laminate energy harvester.

Betts, David N.; Bowen, Christopher R.; Inman, Daniel J.; Weaver, Paul M.; Kim, H. A.

2014-04-01

245

A fail-safe magnetorheological energy absorber for shock and vibration isolation

Magnetorheological (MR) energy absorbers (EAs) are an effective adaptive EA technology with which to maximize shock and vibration isolation. However, to realize maximum performance of the semi-active control system, the off-state (i.e., field off) stroking load of the MREA must be minimized at all speeds, and the dynamic range of the MREA must be maximized at high speed. This study presents a fail-safe MREA (MREA-FS) concept that, can produce a greater dynamic range at all piston speeds. A bias damping force is generated in the MREA-FS using permanent magnetic fields, which enables fail-safe behavior in the case of power failure. To investigate the feasibility and capability of the MREA-FS in the context of the semi-active control systems, a single-degree-of-freedom base excited rigid payload is mathematically constructed and simulated with skyhook control.

Bai, Xian-Xu, E-mail: bai@hfut.edu.cn [Department of Vehicle Engineering, Hefei University of Technology, Hefei 230009 (China); Wereley, Norman M. [Department of Aerospace Engineering, University of Maryland, College Park, Maryland 20742 (United States)

2014-05-07

246

A fail-safe magnetorheological energy absorber for shock and vibration isolation

NASA Astrophysics Data System (ADS)

Magnetorheological (MR) energy absorbers (EAs) are an effective adaptive EA technology with which to maximize shock and vibration isolation. However, to realize maximum performance of the semi-active control system, the off-state (i.e., field off) stroking load of the MREA must be minimized at all speeds, and the dynamic range of the MREA must be maximized at high speed. This study presents a fail-safe MREA (MREA-FS) concept that, can produce a greater dynamic range at all piston speeds. A bias damping force is generated in the MREA-FS using permanent magnetic fields, which enables fail-safe behavior in the case of power failure. To investigate the feasibility and capability of the MREA-FS in the context of the semi-active control systems, a single-degree-of-freedom base excited rigid payload is mathematically constructed and simulated with skyhook control.

Bai, Xian-Xu; Wereley, Norman M.

2014-05-01

247

NASA Astrophysics Data System (ADS)

The effect of the Coriolis interaction upon the sharing of energy between rotational and vibrational excitation during an electronic transition is considered with particular emphasis on recoil-induced excitation during photoionization. If there is a large change in equilibrium bond length upon ionization, then Coriolis coupling leads to a significant transfer of energy between rotational and vibrational excitation. Experimental results for valence ionization of N2 and CO and for carbon 1 s ionization of CO show evidence of this effect.

Thomas, T. Darrah

2014-11-01

248

Mode-Specific Vibrational Energy Relaxation of Amide I and II Modes in N, 2008; ReVised Manuscript ReceiVed: February 2, 2009 The mode-specific vibrational energy relaxation on the potential energy distribution of each mode. The vibrational population relaxation time constants were

Straub, John E.

249

NASA Astrophysics Data System (ADS)

Vibration harvesting has been intensively developed recently and systems have been simulated and realized, but real-life situations (including aircraft Structure Health Monitoring (SHM)involve uneven, low amplitude, low frequency vibrations. In such an unfavorable case, it is very likely that no power can be harvested for a long time. To overcome this, multi-source harvesting is a relevant solution, and in our application both solar and thermal gradient sources are available. We propose in this paper a complete Microsystem including a piezoelectric vibration harvesting module, thermoelectric conversion module, signal processing electronics and supercapacitor. A model is proposed for these elements and a VHDL-AMS simulation of the whole system is presented, showing that the vibration harvesting device alone cannot supply properly a SHM wireless node. Its role is nevertheless important since it is a more reliable source than thermoelectric (which depends on climatic conditions). Moreover, synergies between vibration harvesting and thermoelectric scavenging circuits are presented.

Durou, Hugo; Rossi, Carole; Brunet, Magali; Vanhecke, Claude; Bailly, Nicolas; Ardila, Gustavo; Ourak, Lamine; Ramond, Adrien; Simon, Patrice; Taberna, Pierre-Louis

2008-12-01

250

NASA Astrophysics Data System (ADS)

Piezoelectric vibration energy harvesters with multi-layer stacked structures have been developed. They consist of multi-layer beams, of zigzag configurations, with rigid masses attached between the beams. The rigid masses, which also serve as spacers, are attached to each layer to tune the frequencies of the harvester. Close resonance frequencies and considerable power output can be achieved in multiple modes by varying the positions of the masses. A modal approach is introduced to determine the modal performance conveniently using the mass ratio and the modal electromechanical coupling coefficient, and the required modal parameters are derived using the finite element method. Mass ratio represents the influence of modal mechanical behaviour on the power density. Since the modes with larger mass ratios cause the remaining modes to have smaller mass ratios and lower power densities, a screening process using the modal approach is developed to determine the optimal or near-optimal performance of the harvesters when altering mass positions. This procedure obviates the need for full analysis by pre-selecting the harvester configurations with close resonances and favourable values of mass ratio initially. Furthermore, the multi-layer stacked designs using the modal approach can be used to develop harvesters with different sizes with the power ranging from microwatts to milliwatts.

Xiong, Xingyu; Oyadiji, S. Olutunde

2014-10-01

251

Energy harvesting for self-powered aerostructure actuation

NASA Astrophysics Data System (ADS)

This paper proposes and experimentally investigates applying piezoelectric energy harvesting devices driven by flow induced vibrations to create self-powered actuation of aerostructure surfaces such as tabs, flaps, spoilers, or morphing devices. Recently, we have investigated flow-induced vibrations and limit cycle oscillations due to aeroelastic flutter phenomena in piezoelectric structures as a mechanism to harvest energy from an ambient fluid flow. We will describe how our experimental investigations in a wind tunnel have demonstrated that this harvested energy can be stored and used on-demand to actuate a control surface such as a trailing edge flap in the airflow. This actuated control surface could take the form of a separate and discrete actuated flap, or could constitute rotating or deflecting the oscillating energy harvester itself to produce a non-zero mean angle of attack. Such a rotation of the energy harvester and the associated change in aerodynamic force is shown to influence the operating wind speed range of the device, its limit cycle oscillation (LCO) amplitude, and its harvested power output; hence creating a coupling between the device's performance as an energy harvester and as a control surface. Finally, the induced changes in the lift, pitching moment, and drag acting on a wing model are quantified and compared for a control surface equipped with an oscillating energy harvester and a traditional, static control surface of the same geometry. The results show that when operated in small amplitude LCO the energy harvester adds negligible aerodynamic drag.

Bryant, Matthew; Pizzonia, Matthew; Mehallow, Michael; Garcia, Ephrahim

2014-04-01

252

applications of electrets such as acoustic/mechanical transducers and air filter have been proposed [14 for large output power. Figure 2 shows power spectra of vibration acceleration in a car cabin. Since high Figure 1. Vibration-driven power generator. Figure 2. Power spectra of vibration in a car cabin. -180

Kasagi, Nobuhide

253

IEEE POWER ENGINEERING SOCIETY ENERGY DEVELOPMENT AND POWER GENERATION COMMITTEE

IEEE POWER ENGINEERING SOCIETY ENERGY DEVELOPMENT AND POWER GENERATION COMMITTEE Latin America Sponsored by: International Practices for Energy Development and Power Generation Chairs: Luiz Barroso, PSR utilities (Discos) that buy power supply from generators in both the long term and sport markets. For more

Catholic University of Chile (Universidad CatÃ³lica de Chile)

254

Energy Industry Powers CTE Program

ERIC Educational Resources Information Center

Michael Fields is a recent graduate of Buckeye Union High School in Buckeye, Arizona. Fields is enrolled in the Estrella Mountain Community College (EMCC) Get Into Energy program, which means he is well on his way to a promising career. Specializing in power plant technology, in two years he will earn a certificate that will all but guarantee a…

Khokhar, Amy

2012-01-01

255

Evaluation of whole-body vibration exposure using a fourth power method and comparison with ISO 2631

NASA Astrophysics Data System (ADS)

Vertical whole-body vibrations recorded at the driver-seat interface on skidders were analyzed by using a "fourth power" procedure for predicting the discomfort and the degradation in health caused by the motions. The root-mean-square acceleration and the crest factor of the vibrations were also evaluated for eight skidder vehicles by fixing the integration period at 1 minute. For motions with large crest factor values, a relationship was found for predicting the "fourth power" vibration parameters, such as the root-mean-quad acceleration and the Vibration Dose Value from the root-mean-square acceleration and the crest factor. That relationship was found to be in good general agreemnt with the experimental results, indicating that, for the same rms level, greater discomfort would be felt with increasing peak levels. With respect to the "fourth power" procedure, it was established that for vibration exposure on skidders, the ISO 2631 evaluation procedure would underestimate the vibration dose by up to three times for comfort and as much as seven times for health, depending on the creast factor value.

Boileau, P.-E.; Turcot, D.; Scory, H.

1989-02-01

256

Mechanism of vibrational energy dissipation of free OH groups at the air–water interface

Interfaces of liquid water play a critical role in a wide variety of processes that occur in biology, a variety of technologies, and the environment. Many macroscopic observations clarify that the properties of liquid water interfaces significantly differ from those of the bulk liquid. In addition to interfacial molecular structure, knowledge of the rates and mechanisms of the relaxation of excess vibrational energy is indispensable to fully understand physical and chemical processes of water and aqueous solutions, such as chemical reaction rates and pathways, proton transfer, and hydrogen bond dynamics. Here we elucidate the rate and mechanism of vibrational energy dissipation of water molecules at the air–water interface using femtosecond two-color IR-pump/vibrational sum-frequency probe spectroscopy. Vibrational relaxation of nonhydrogen-bonded OH groups occurs at a subpicosecond timescale in a manner fundamentally different from hydrogen-bonded OH groups in bulk, through two competing mechanisms: intramolecular energy transfer and ultrafast reorientational motion that leads to free OH groups becoming hydrogen bonded. Both pathways effectively lead to the transfer of the excited vibrational modes from free to hydrogen-bonded OH groups, from which relaxation readily occurs. Of the overall relaxation rate of interfacial free OH groups at the air–H2O interface, two-thirds are accounted for by intramolecular energy transfer, whereas the remaining one-third is dominated by the reorientational motion. These findings not only shed light on vibrational energy dynamics of interfacial water, but also contribute to our understanding of the impact of structural and vibrational dynamics on the vibrational sum-frequency line shapes of aqueous interfaces. PMID:24191016

Hsieh, Cho-Shuen; Campen, R. Kramer; Okuno, Masanari; Backus, Ellen H. G.; Nagata, Yuki; Bonn, Mischa

2013-01-01

257

Voltage tuning of vibrational mode energies in single-molecule junctions

Vibrational modes of molecules are fundamental properties determined by intramolecular bonding, atomic masses, and molecular geometry, and often serve as important channels for dissipation in nanoscale processes. Although single-molecule junctions have been used to manipulate electronic structure and related functional properties of molecules, electrical control of vibrational mode energies has remained elusive. Here we use simultaneous transport and surface-enhanced Raman spectroscopy measurements to demonstrate large, reversible, voltage-driven shifts of vibrational mode energies of C60 molecules in gold junctions. C60 mode energies are found to vary approximately quadratically with bias, but in a manner inconsistent with a simple vibrational Stark effect. Our theoretical model instead suggests that the mode shifts are a signature of bias-driven addition of electronic charge to the molecule. These results imply that voltage-controlled tuning of vibrational modes is a general phenomenon at metal–molecule interfaces and is a means of achieving significant shifts in vibrational energies relative to a pure Stark effect. PMID:24474749

Li, Yajing; Doak, Peter; Kronik, Leeor; Neaton, Jeffrey B.; Natelson, Douglas

2014-01-01

258

Stresa, Italy, 26-28 April 2006 VIBRATIONAL ENERGY SCAVENGING WITH SI TECHNOLOGY

Stresa, Italy, 26-28 April 2006 VIBRATIONAL ENERGY SCAVENGING WITH SI TECHNOLOGY ELECTROMAGNETIC present the design and optimization of an electromagnetic inertial microgenerator for energy scavenging. For such applications, an interesting option is the use of inertial microgenerators for energy scavenging from

Boyer, Edmond

259

Random vibration analysis of the Topaz-II nuclear reactor power system. Master`s thesis

The TOPAZ-II Ya-21U is one of six Russian made space nuclear power systems which is based on theomionic power conversion. The U.S. is presently analyzing TOPAZ-II to determine the reliability and feasibility of using this system. A structural analysis test was conducted on the TOPAZ unit in May 1993 to provide data from which modal parameters could be identified. This test showed the fundamental frequency to be 10.5 Hz, yet the test results that the Russians conducted identified a fundamental frequency of 5 Hz. Another finite element model was created incorporating new developments in TOPAZ-II and modifications to the finite element model to better simulate the mass properties of the TOPAZ-II2. A second structural analysis test was conducted on the TOPAZ unit 06-09 September 1994. This thesis focuses on the random vibration analysis of the TOPAZ-II Ya-2lU utilizing the most recent test results and the Master Series (updated version) I-DEAS software. The modal respose of the model and simulated random vibration tests were within 8.33%. This model is a feasible tool which can be used to analyze the TOPAZ unit without testing the unit to fatigue.

Campbell, S.E.

1995-06-01

260

Whole-body vibration training is a method for muscle strengthening that is increasingly used in a variety of clinical situations. Key descriptors of vibration devices include the frequency, the amplitude, and the direction of the vibration movement. In a typical vibration session, the user stands on the device in a static position or performs dynamic movements. Most authors hypothesize that vibrations stimulate muscle spindles and alpha-motoneurons, which initiate a muscle contraction. An immediate effect of a non-exhausting vibration session is an increase in muscle power. Most studies of the longer term use of vibration treatment in various disorders have pursued three therapeutic aims: increasing muscle strength, improving balance, and increasing bone mass. In a small pilot trial in children we noted improvements in standing function, lumbar spine bone mineral density, tibial bone mass, and calf muscle cross-sectional area. PMID:19740225

Rauch, Frank

2009-10-01

261

Vibrational energy flow controls internal conversion in a transition metal complex.

Internal conversion (IC) between excited electronic states is a fundamental photophysical process that is important for understanding protection from UV radiation, energy transfer pathways and electron injection in artificial photosynthetic systems and organic solar cells. We have studied IC between three singlet MLCT states in an iridium complex using femtosecond fluorescence spectroscopy. Very fast IC with a time constant of <20 fs is observed from the highest state and a much slower relaxation to the lowest energy singlet state on a 70 fs time scale. The abrupt slowdown of the relaxation rate occurs when there is >0.6 eV of vibrational energy stored in the complex that has to be dissipated by intramolecular vibrational redistribution before further IC to the lower energy states can occur. These results show that the ability to dissipate vibrational energy can control the relaxation process in this class of materials. PMID:20690629

Hedley, Gordon J; Ruseckas, Arvydas; Samuel, Ifor D W

2010-09-01

262

On the ro-vibrational energies for the lithium dimer; maximum-possible rotational levels

The Deng-Fan potential is used to discuss the reliability of the improved Greene-Aldrich approximation and the factorization recipe of Badawi et al.'s [17] for the central attractive/repulsive core. The factorization recipe is shown to be a more reliable approximation and is used to obtain the ro-vibrational energies for the lithium dimer. For each vibrational state only a limited number of the rotational levels are found to be supported by the lithium dimer.

Omar Mustafa

2015-01-27

263

Collisional transfer of roto-vibrational energy from quantum calculations: The He-HF system

Summary The problem of simultaneous vibrational and rotational excitations of HF molecules in collision with helium has been approached\\u000a via a quantum-mechanical treatment of the full dynamics and by employing a very accurate potential-energy surface suggested\\u000a earlier in the literature. The complicated coupling of rotational and vibrational channels has been partly simplified by taking\\u000a advantage of their different time scales, thus

F. A. Gianturco; U. T. Lamanna; G. Petrella

1984-01-01

264

We calculate the potential energy curves, the permanent dipole moment curves, and the lifetimes of the ground and excited vibrational states of the heteronuclear alkali dimers XY (X, Y = Li, Na, K, Rb, Cs) in the X{sup 1}?{sup +} electronic state using the coupled cluster with singles doubles and triples method. All-electron quadruple-? basis sets with additional core functions are used for Li and Na, and small-core relativistic effective core potentials with quadruple-? quality basis sets are used for K, Rb, and Cs. The inclusion of the coupled cluster non-perturbative triple excitations is shown to be crucial for obtaining the accurate potential energy curves. A large one-electron basis set with additional core functions is needed for the accurate prediction of permanent dipole moments. The dissociation energies are overestimated by only 14 cm{sup ?1} for LiNa and by no more than 114 cm{sup ?1} for the other molecules. The discrepancies between the experimental and calculated harmonic vibrational frequencies are less than 1.7 cm{sup ?1}, and the discrepancies for the anharmonic correction are less than 0.1 cm{sup ?1}. We show that correlation between atomic electronegativity differences and permanent dipole moment of heteronuclear alkali dimers is not perfect. To obtain the vibrational energies and wave functions the vibrational Schrödinger equation is solved with the B-spline basis set method. The transition dipole moments between all vibrational states, the Einstein coefficients, and the lifetimes of the vibrational states are calculated. We analyze the decay rates of the vibrational states in terms of spontaneous emission, and stimulated emission and absorption induced by black body radiation. In all studied heteronuclear alkali dimers the ground vibrational states have much longer lifetimes than any excited states.

Fedorov, Dmitry A.; Varganov, Sergey A., E-mail: svarganov@unr.edu [Department of Chemistry, University of Nevada, Reno, 1664 N. Virginia St., Reno, Nevada 89557-0216 (United States); Derevianko, Andrei [Department of Physics, University of Nevada, Reno, 1664 N. Virginia St., Reno, Nevada 89557-0220 (United States)] [Department of Physics, University of Nevada, Reno, 1664 N. Virginia St., Reno, Nevada 89557-0220 (United States)

2014-05-14

265

Vibration Isolation of a Locomotive Mounted Energy Storage Flywheel

system are provided at the end of each section. Section 1 introduces the problem and method being used to study the vibration under different circumstances. Section 2 analyzes the response of the flywheel system to sinusoidal floor input given by Ahmadian...

Zhang, Xiaohua

2011-02-22

266

NASA Astrophysics Data System (ADS)

The paper presents data of operating vibroseismic observations using high-power stationary 100-tons and moveable 40-tons vibration sources, which have been carried out in Russia for 30 years. It is shown that investigations using high-power vibration sources open new possibilities for study stressedly-deformed condition of the Earth`s crust and the upper mantle and tectonic process in them. Special attention is given to developing operating seismic translucences of the Earth`s crust and the upper mantle using high-power 40-tons vibration sources. As a result of experimental researches there was proved high stability and repeatability of vibration effects. There were carried out long period experiments of many days with vibration source sessions of every two hours with the purpose of monitoring accuracy estimation. It was determined, that repeatability of vibroseismic effects (there was researched time difference of repeated sessions of P- and S-waves from crystal rocks surface) could be estimated as 10-3 - 10-4 sec. It is ten times less than revealed here annual variations of kinematic parameters according to regime vibroseismic observations. It is shown, that on hard high-speed grounds radiation spectrum becomes narrowband and is dislocated to high frequency; at the same time quantity of multiple high-frequency harmonic is growing. At radiation on soft sedimentary grounds (sand, clay) spectrum of vibration source in near zone is more broadband, correlograms are more compact. there Correspondence of wave fields from 40-tons vibration sources and explosions by reference waves from boundaries in he Earth`s crust and the upper mantle at record distance of 400 km was proved by many experiments in various regions of Russia; there was carried out the technique of high-power vibration sources grouping for increase of effectiveness of emanation and increase of record distance. According to results of long-term vibroseismic monitoring near Novosibirsk (1997-2012) there are determined variations in velocities of longitudinal and transverse waves. Both from 100-tons and 40-tons vibration sources there are distinctly determined annual and semiannual variations, and also variations of 120 and 90 days. There is determined correlations of revealed variations of P- and S-wave velocities with drowning of the upper part of the Earth`s crust because of season changes of water volumes in the biggest Novosibirsk water reservoir. There were carried out experiments on aperture widening of operating vibroseismic observations in seismic active zones of the South of Altay. All these results prove possibility of using moveable collapsible 40-tons vibration sources for active monitoring of seismic dangerous zones, nuclear power plants, nuclear waste storage etc.

Soloviev, V. M.; Seleznev, V. S.; Emanov, A. F.; Kashun, V. N.; Elagin, S. A.; Romanenko, I.; Shenmayer, A. E.; Serezhnikov, N.

2013-05-01

267

The initial vibrational energy distribution of molecules that collide with a hot surface has been varied. The effect of the variation on the collisional reaction probability (P/sub c/) has been studied under single collision conditions. These experiments provide a more sensitive test of the relative suitability of various analytical forms for the collisional transition probability matrix P than has been achieved previously in earlier VEM experiments. The reaction system is the isomerization of cyclobutene to 1, 3-butadiene. A seasoned fused quartz surface was used over the temperature range T/sub r/ = 600--900 K. Variation of the initial vibrational energy population vector of cyclobutene molecules was made by change of their initial temperature T/sub c/ in the range 273--620 K. The experimental collisional efficiency ..beta../sub 1/ declined from 0.31 to 0.013 over the combination temperature ranges T/sub r/, T/sub c/ = 600,500 to 900,273. Stochastic models of the vibrational transition probability were fitted to the data and provided values for the average amount of energy (<..delta..E'>/sub E//sub 0/) transferred from the hot molecules in a down transition from the threshold energy level E/sub 0/; Gaussian or Boltzmann exponential forms of P prove to be the most suitable to fit the data. Calculated values, <..delta..E'>/sub E//sub 0/ on the basis of a Gaussian function model for P declined from 5600 to 3700 cm/sup -1/ with increase in the surface temperature from 600 to 900 K.

Arakawa, R.; Kelley, D.F.; Rabinovitch, B.S.

1982-03-01

268

Low power interface IC's for electrostatic energy harvesting applications

NASA Astrophysics Data System (ADS)

The application of wireless distributed micro-sensor systems ranges from equipment diagnostic and control to real time structural and biomedical monitoring. A major obstacle in developing autonomous micro-sensor networks is the need for local electric power supply, since using a battery is often not a viable solution. This void has sparked significant interest in micro-scale power generators based on electrostatic, piezoelectric and electromagnetic energy conversion that can scavenge ambient energy from the environment. In comparison to existing energy harvesting techniques, electrostatic-based power generation is attractive as it can be integrated using mainstream silicon technologies while providing higher power densities through miniaturization. However the power output of reported electrostatic micro-generators to date does not meet the communication and computation requirements of wireless sensor nodes. The objective of this thesis is to investigate novel CMOS-based energy harvesting circuit (EHC) architectures to increase the level of harvested mechanical energy in electrostatic converters. The electronic circuits that facilitate mechanical to electrical energy conversion employing variable capacitors can either have synchronous or asynchronous architectures. The later does not require synchronization of electrical events with mechanical motion, which eliminates difficulties in gate clocking and the power consumption associated with complex control circuitry. However, the implementation of the EHC with the converter can be detrimental to system performance when done without concurrent optimization of both elements, an aspect mainly overlooked in the literature. System level analysis is performed to show that there is an optimum value for either the storage capacitor or cycle number for maximum scavenging of ambient energy. The analysis also shows that maximum power is extracted when the system approaches synchronous operation. However, there is a region of interest where the storage capacitor can be optimized to produce almost 70% of the ideal power taken as the power harvested with synchronous converters when neglecting the power consumption associated with synchronizing control circuitry. Theoretical predictions are confirmed by measurements on an asynchronous EHC implemented with a macro-scale electrostatic converter prototype. Based on the preceding analysis, the design of a novel ultra low power electrostatic integrated energy harvesting circuit is proposed for efficient harvesting of mechanical energy. The fundamental challenges of designing reliable low power sensing circuits for charge constrained electrostatic energy harvesters with capacity to self power its controller and driver stages are addressed. Experimental results are presented for a controller design implemented in AMI 0.7muM high voltage CMOS process using a macro-scale electrostatic converter prototype. The EHC produces 1.126muW for a power investment of 417nW with combined conduction and controller losses of 450nW which is a 20-30% improvement compared to prior art on electrostatic EHCs operating under charge constrain. Inherently dual plate variable capacitors harvest energy only during half of the mechanical cycle with the other half unutilized for energy conversion. To harvest mechanical energy over the complete mechanical vibration cycle, a low power energy harvesting circuit (EHC) that performs charge constrained synchronous energy conversion on a tri-plate variable capacitor for maximizing energy conversion is proposed. The tri-plate macro electrostatic generator with capacitor variation of 405pF to 1.15nF and 405pF to 1.07nF on two complementary adjacent capacitors is fabricated and used in the characterization of the designed EHC. The integrated circuit fabricated in AMI 0.7muM high voltage CMOS process, produces a total output power of 497nW to a 10muF reservoir capacitor from a 98Hz vibration signal. In summary, the thesis lays out the theoretical and experimental foundation for overcoming the main challenges associated with the desi

Kempitiya, Asantha

269

ENergy and Power Evaluation Program

In the late 1970s, national and international attention began to focus on energy issues. Efforts were initiated to design and test analytical tools that could be used to assist energy planners in evaluating energy systems, particularly in developing countries. In 1984, the United States Department of Energy (DOE) commissioned Argonne National Laboratory`s Decision and Information Sciences Division (DIS) to incorporate a set of analytical tools into a personal computer-based package for distribution in developing countries. The package developed by DIS staff, the ENergy and Power Evaluation Program (ENPEP), covers the range of issues that energy planners must face: economic development, energy demand projections, supply-and-demand balancing, energy system expansion, and environmental impact analysis. Following the original DOE-supported development effort, the International Atomic Energy Agency (IAEA), with the assistance from the US Department of State (DOS) and the US Department of Energy (DOE), provided ENPEP training, distribution, and technical support to many countries. ENPEP is now in use in over 60 countries and is an international standard for energy planning tools. More than 500 energy experts have been trained in the use of the entire ENPEP package or some of its modules during the international training courses organized by the IAEA in collaboration with Argonne`s Decision and Information Sciences (DIS) Division and the Division of Educational Programs (DEP). This report contains the ENPEP program which can be download from the internet. Described in this report is the description of ENPEP Program, news, forums, online support and contacts.

NONE

1996-11-01

270

Sound power radiation from a vibrating structure in terms of structure-dependent radiation modes

NASA Astrophysics Data System (ADS)

As a good supplement of conventional acoustic radiation modes (a-modes), a set of so-called "structure-dependent radiation modes" (s-modes) is introduced to describe the sound power radiation from a vibrating structure. Differing from a-modes, s-modes are determined by not only the acoustic resistance matrix of the structure but also the frequency-independent normal modes of the structure. Such a new definition has the following main advantages over the conventional one: (1) it can reflect directly the influences of dynamic properties (e.g., boundary conditions) of the structures on its sound power radiation; (2) the number of s-modes generated is generally less than that of a-modes since the former depends on the number of structural modes involved in the vibration while the latter depends on the number of segmented elemental radiators of the structure, and consequently, the demand for large data storage can be greatly alleviated, especially for large structures and/or higher frequency vibrations; (3) the set of s-modes possesses a better convergence than that of a-modes because the higher ordered s-modes can decay more rapidly than the same ordered a-modes. Two baffled, finite, models, i.e., a simple beam and a thin plate, are employed to investigate numerically the acoustic properties of s-modes, and then compared with those of a-modes. It has been shown that the two sets of radiation modes share a very similar frequency-dependent behavior in that the radiation efficiency falls off very rapidly with increasing mode order at low frequency range (typically with kl<1). Meanwhile, the number of s-modes required to describe the total sound power radiation is found to be the same as that of a-modes. Consequently, an appropriate truncation of a-modes can be achieved by using the number of vibrational modes involved. Nevertheless, the odd-ordered (even-ordered) s-modes are found only associated with the odd-numbered (even-ordered) structural modes. In case of only few of the s-modes dominating, each s-mode tends to be largely affected either by the same ordered structural mode for a non-resonant frequency or by the resonant mode for a resonant frequency. As a result, the coupling relations between the dominating radiation modes and the associated structural modes can be revealed explicitly. In general, s-modes are recommended to be used to describe the sound power radiation from a vibrating structure whose geometry sizes are much larger than the acoustic wavelength, should its structural modes and the associated modal amplitudes have been somehow obtained.

Ji, Lin; Bolton, J. Stuart

2015-01-01

271

NASA Astrophysics Data System (ADS)

While the vibration power for a set of harmonic force and velocity signals is well defined and known, it is not as popular yet for a set of stationary random force and velocity processes, although it can be found in some literatures. In this paper, the definition of the vibration power for a set of non-stationary random force and velocity signals will be derived for the purpose of a time-frequency analysis based on the definitions of the vibration power for the harmonic and stationary random signals. The non-stationary vibration power, defined as the short-time average of the product of the force and velocity over a given frequency range of interest, can be calculated by three methods: the Wigner-Ville distribution, the short-time Fourier transform, and the harmonic wavelet transform. The latter method is selected in this paper because band-pass filtering can be done without phase distortions, and the frequency ranges can be chosen very flexibly for the time-frequency analysis. Three algorithms for the time-frequency analysis of the non-stationary vibration power using the harmonic wavelet transform are discussed. The first is an algorithm for computation according to the full definition, while the others are approximate. Noting that the force and velocity decomposed into frequency ranges of interest by the harmonic wavelet transform are constructed with coefficients and basis functions, for the second algorithm, it is suggested to prepare a table of time integrals of the product of the basis functions in advance, which are independent of the signals under analysis. How to prepare and utilize the integral table are presented. The third algorithm is based on an evolutionary spectrum. Applications of the algorithms to the time-frequency analysis of the vibration power transmitted from an excitation source to a receiver structure in a simple mechanical system consisting of a cantilever beam and a reaction wheel are presented for illustration.

Heo, YongHwa; Kim, Kwang-joon

2015-02-01

272

Collisional vibrational energy transfer of OH (A 2Sigma + , v'=1)

NASA Astrophysics Data System (ADS)

Vibrational energy transfer (VET) and quenching of the v'=1 level of A 2?+ OH have been studied using laser-induced fluorescence in a discharge flow cell at room temperature. VET cross sections (Å2) are N2, 30.1±2.8; O2, 2.8±0.3; Ar, 0.56±0.05; H2O, 8.6±0.6. The rotational energy distribution in v'=0 following the VET event was determined for nine colliders. It is nonthermal, generally populating high rotational levels. There are three broad categories of colliders that cause varying degrees of vibrational to rotational energy transfer; H2, D2, and CH4 show the least; N2, CO2, CF4, and N2O more; and O2 and Ar the most, with about one-third of the vibrational energy appearing as OH rotation.

Williams, Leah R.; Crosley, David R.

1996-05-01

273

NASA Astrophysics Data System (ADS)

We report the relative efficacy of vibrational and translational energy in overcoming the barrier to dissociative adsorption of D2 on a Cu(111) surface. This is determined by measuring variation of adsorption probability with kinetic energies, Ei, and vibrational temperature. At the highest energy (Ei=0.83 eV) adsorption is predominantly due to ground-state D2; molecules in excited vibrational states play the dominant role for Ei below ~0.5 eV. A detailed analysis provides estimated adsorption probability versus energy functions for D2 in vibrational states v=0 to v=3.

Rettner, C. T.; Auerbach, D. J.; Michelsen, H. A.

1992-02-01

274

Analysis of vibrational-translational energy transfer using the direct simulation Monte Carlo method

NASA Technical Reports Server (NTRS)

A new model is proposed for energy transfer between the vibrational and translational modes for use in the direct simulation Monte Carlo method (DSMC). The model modifies the Landau-Teller theory for a harmonic oscillator and the rate transition is related to an experimental correlation for the vibrational relaxation time. Assessment of the model is made with respect to three different computations: relaxation in a heat bath, a one-dimensional shock wave, and hypersonic flow over a two-dimensional wedge. These studies verify that the model achieves detailed balance, and excellent agreement with experimental data is obtained in the shock wave calculation. The wedge flow computation reveals that the usual phenomenological method for simulating vibrational nonequilibrium in the DSMC technique predicts much higher vibrational temperatures in the wake region.

Boyd, Iain D.

1991-01-01

275

Non-classicality of the molecular vibrations assisting exciton energy transfer at room temperature

NASA Astrophysics Data System (ADS)

Advancing the debate on quantum effects in light-initiated reactions in biology requires clear identification of non-classical features that these processes can exhibit and utilize. Here we show that in prototype dimers present in a variety of photosynthetic antennae, efficient vibration-assisted energy transfer in the sub-picosecond timescale and at room temperature can manifest and benefit from non-classical fluctuations of collective pigment motions. Non-classicality of initially thermalized vibrations is induced via coherent exciton-vibration interactions and is unambiguously indicated by negativities in the phase-space quasi-probability distribution of the effective collective mode coupled to the electronic dynamics. These quantum effects can be prompted upon incoherent input of excitation. Our results therefore suggest that investigation of the non-classical properties of vibrational motions assisting excitation and charge transport, photoreception and chemical sensing processes could be a touchstone for revealing a role for non-trivial quantum phenomena in biology.

O'Reilly, Edward J.; Olaya-Castro, Alexandra

2014-01-01

276

The vibrational energies of ozone up to the dissociation threshold: Dynamics calculations present an ab initio potential energy surface for the ground electronic state of ozone. It is global, i. All bound states of nonrotating ozone up to more than 99% of the dissociation energy are calculated

Farantos, Stavros C.

277

Energy Finite Element Analysis Developments for Vibration Analysis of Composite Aircraft Structures

NASA Technical Reports Server (NTRS)

The Energy Finite Element Analysis (EFEA) has been utilized successfully for modeling complex structural-acoustic systems with isotropic structural material properties. In this paper, a formulation for modeling structures made out of composite materials is presented. An approach based on spectral finite element analysis is utilized first for developing the equivalent material properties for the composite material. These equivalent properties are employed in the EFEA governing differential equations for representing the composite materials and deriving the element level matrices. The power transmission characteristics at connections between members made out of non-isotropic composite material are considered for deriving suitable power transmission coefficients at junctions of interconnected members. These coefficients are utilized for computing the joint matrix that is needed to assemble the global system of EFEA equations. The global system of EFEA equations is solved numerically and the vibration levels within the entire system can be computed. The new EFEA formulation for modeling composite laminate structures is validated through comparison to test data collected from a representative composite aircraft fuselage that is made out of a composite outer shell and composite frames and stiffeners. NASA Langley constructed the composite cylinder and conducted the test measurements utilized in this work.

Vlahopoulos, Nickolas; Schiller, Noah H.

2011-01-01

278

NASA Astrophysics Data System (ADS)

This letter investigates the energy harvesting from the horizontal coherent resonance of a vertical cantilever beam subjected to the vertical base excitation. The potential energy of the system has two symmetric potential wells. So, under vertical excitation, the system can jump between two potential wells, which will lead to the large vibration in horizontal direction. Two piezoelectric patches are pasted to harvest the energy. From experiment, it is found that the vertical excitation can make the beam turn to be bistable. The system can transform vertical vibration into horizontal vibration of low frequency when excited by harmonic motion. The horizontal coherence resonance can be observed when excited by a vertical white noise. The corresponding output voltages of piezoelectric films reach high values.

Lan, C. B.; Qin, W. Y.

2014-09-01

279

This letter investigates the energy harvesting from the horizontal coherent resonance of a vertical cantilever beam subjected to the vertical base excitation. The potential energy of the system has two symmetric potential wells. So, under vertical excitation, the system can jump between two potential wells, which will lead to the large vibration in horizontal direction. Two piezoelectric patches are pasted to harvest the energy. From experiment, it is found that the vertical excitation can make the beam turn to be bistable. The system can transform vertical vibration into horizontal vibration of low frequency when excited by harmonic motion. The horizontal coherence resonance can be observed when excited by a vertical white noise. The corresponding output voltages of piezoelectric films reach high values.

Lan, C. B.; Qin, W. Y. [Department of Engineering Mechanics, Northwestern Polytechnical University, Xi'an 710072 (China)

2014-09-15

280

NASA Astrophysics Data System (ADS)

The reduction of power consumption of sensors allows the local power supply or wireless sensor networks. This paper introduces the results of design and experiments on devices for harvesting energy from vibrations of machines. The main contribution of this research is the empirical evaluation of different technical solutions able to improve harvester performances and sensing system duty cycle. Satisfactory results have been achieved in lowering of resonance by levitating suspensions and in increasing of Q-factor by studying the air flows. Output power values of 10mW (5.7Hz, 1.4g) and 115mW (3.2Hz, 0.2g) were obtained for piezoelectric and inductive harvesters respectively.

Somà, A.; De Pasquale, G.

2013-05-01

281

A bi-annular-gap magnetorheological energy absorber for shock and vibration mitigation

NASA Astrophysics Data System (ADS)

For semi-active shock and vibration mitigation systems using magnetorheological energy absorbers (MREAs), the minimization of the field-off damper force of the MREA at high speed is of particular significance because the damper force due to the viscous damping at high speed becomes too excessive and thus the controllable dynamic force range that is defined by the ratio of the field-on damper force to the field-off damper force is significantly reduced. In this paper, a bi-annular-gap MREA with an inner-set permanent magnet is proposed to decrease the field-off damper force at high speed while keeping appropriate dynamic force range for improving shock and vibration mitigation performance. In the bi-annular-gap MREA, two concentric annular gaps are configured in parallel so as to decrease the baseline damper force and both magnetic activation methods using the electromagnetic coil winding and the permanent magnet are used to keep holding appropriate magnetic intensity in these two concentric annular gaps in the consideration of failure of the electric power supply. An initial field-on damper force is produced by the magnetic field bias generated from the inner-set permanent magnet. The initial damper force of the MREA can be increased (or decreased) through applying positive (or negative) current to the electromagnetic coil winding inside the bi-annular-gap MREA. After establishing the analytical damper force model of the bi-annular-gap MREA using a Bingham-plastic nonlinear fluid model, the principle and magnetic properties of the MREA are analytically validated and analyzed via electromagnetic finite element analysis (FEA). The performance of the bi-annular-gap MREA is also theoretically compared with that of a traditional single-annular- gap MREA with the constraints of an identical volume by the performance matrix, such as the damper force, dynamic force range, and Bingham number with respect to different excitation velocities.

Bai, Xian-Xu; Wereley, Norman M.; Choi, Young-Tai; Wang, Dai-Hua

2012-04-01

282

Tidal energy in electric power systems

This paper discusses the uses and advantages of tidal energy in restructured power systems. The paper defines the resources as well as the ways in which tidal energy is converted into electricity. The paper also reviews a few tidal power projects around the world. It also shows the working of hydro tidal power plant. A comparative review of renewable energy

S. Sheth; M. Shahidehpour

2005-01-01

283

Voltage, energy and power in electric circuits

Voltage, energy and power in electric circuits Science teaching unit #12;Disclaimer The Department-2008DVD-EN Voltage, energy and power in electric circuits #12;#12;Â© Crown copyright 2008 1The National Strategies | Secondary Voltage, energy and power in electric circuits 00094-2008DVD-EN Contents Voltage

Berzins, M.

284

Comparison of Five Topologies of Cantilever-based MEMS Piezoelectric Vibration Energy Harvesters

NASA Astrophysics Data System (ADS)

In the realm of MEMS piezoelectric vibration energy harvesters, cantilever-based designs are by far the most popular. Despite being deceptively simple, the active piezoelectric area near the clamped end is able to accumulate maximum strain-generated-electrical-charge, while the free end is able to accommodate a proof mass without compromising the effective area of the piezoelectric generator since it experiences minimal strain anyway. While other contending designs do exist, this paper investigates five micro-cantilever (MC) topologies, namely: a plain MC, a tapered MC, a lined MC, a holed MC and a coupled MC, in order to assess their relative performance as an energy harvester. Although a classical straight and plain MC offers the largest active piezoelectric area, alternative MC designs can potentially offer higher average mechanical strain distribution for a given mechanical loading. Numerical simulation and experimental comparison of these 5 MCs (0.5 ? AlN on 10 ?m Si) with the same practical dimensions of 500 ?m and 2000 ?m, suggest a cantilever with a coupled subsidiary cantilever yield the best power performance, closely followed by the classical plain topology.

Jia, Y.; Seshia, A. A.

2014-11-01

285

Theoretical study of internal vibrational relaxation and energy transport in polyatomic molecules.

We attempted to theoretically characterize internal vibrational relaxation and energy relaxation pathways due to anharmonicity in polyatomic molecules. Energy transport dynamics have been modeled based on a generalization of Marcus electron transfer theory. Modifications have been made to our previously developed theory in order to improve the description of internal vibrational dynamics. We applied our method to several molecules studied experimentally by relaxation-assisted two-dimensional infrared spectroscopy (RA 2DIR). The theoretical predictions were found to be consistent with the majority of the experimental data. PMID:23240557

Tesar, Sarah L; Kasyanenko, Valeriy M; Rubtsov, Igor V; Rubtsov, Grigory I; Burin, Alexander L

2013-01-17

286

NASA Astrophysics Data System (ADS)

Single collision vibrational energy transfer for a canonical ensemble (t=300K) of cyclobutene molecules at a heated liquid gallium surface has been studied from 450K to 700K. Transport above the reaction threshold for isomerization to butadiene (E sub 0 = 32.4 kcal/mole) was used as the criterion for efficiency of vibrational energy accommodation. The efficiency was found to fall below strong collider behavior above 625K. Evidence of surface catalysis became important below 525K. The observed behavior is reminiscent of that found previously for other liquid (Sn) and solid (Au) metal surfaces.

Oswald, D. A.; Nilsson, W. B.; Rabinovitch, B. S.

1985-12-01

287

Second-order many-body perturbation expansions of vibrational Dyson self-energies.

Second-order many-body perturbation theories for anharmonic vibrational frequencies and zero-point energies of molecules are formulated, implemented, and tested. They solve the vibrational Dyson equation self-consistently by taking into account the frequency dependence of the Dyson self-energy in the diagonal approximation, which is expanded in a diagrammatic perturbation series up to second order. Three reference wave functions, all of which are diagrammatically size consistent, are considered: the harmonic approximation and diagrammatic vibrational self-consistent field (XVSCF) methods with and without the first-order Dyson geometry correction, i.e., XVSCF[n] and XVSCF(n), where n refers to the truncation rank of the Taylor-series potential energy surface. The corresponding second-order perturbation theories, XVH2(n), XVMP2[n], and XVMP2(n), are shown to be rigorously diagrammatically size consistent for both total energies and transition frequencies, yield accurate results (typically within a few cm(-1) at n = 4 for water and formaldehyde) for both quantities even in the presence of Fermi resonance, and have access to fundamentals, overtones, and combinations as well as their relative intensities as residues of the vibrational Green's functions. They are implemented into simple algorithms that require only force constants and frequencies of the reference methods (with no basis sets, quadrature, or matrix diagonalization at any stage of the calculation). The rules for enumerating and algebraically interpreting energy and self-energy diagrams are elucidated in detail. PMID:23883014

Hermes, Matthew R; Hirata, So

2013-07-21

288

Second-order many-body perturbation expansions of vibrational Dyson self-energies

NASA Astrophysics Data System (ADS)

Second-order many-body perturbation theories for anharmonic vibrational frequencies and zero-point energies of molecules are formulated, implemented, and tested. They solve the vibrational Dyson equation self-consistently by taking into account the frequency dependence of the Dyson self-energy in the diagonal approximation, which is expanded in a diagrammatic perturbation series up to second order. Three reference wave functions, all of which are diagrammatically size consistent, are considered: the harmonic approximation and diagrammatic vibrational self-consistent field (XVSCF) methods with and without the first-order Dyson geometry correction, i.e., XVSCF[n] and XVSCF(n), where n refers to the truncation rank of the Taylor-series potential energy surface. The corresponding second-order perturbation theories, XVH2(n), XVMP2[n], and XVMP2(n), are shown to be rigorously diagrammatically size consistent for both total energies and transition frequencies, yield accurate results (typically within a few cm-1 at n = 4 for water and formaldehyde) for both quantities even in the presence of Fermi resonance, and have access to fundamentals, overtones, and combinations as well as their relative intensities as residues of the vibrational Green's functions. They are implemented into simple algorithms that require only force constants and frequencies of the reference methods (with no basis sets, quadrature, or matrix diagonalization at any stage of the calculation). The rules for enumerating and algebraically interpreting energy and self-energy diagrams are elucidated in detail.

Hermes, Matthew R.; Hirata, So

2013-07-01

289

NASA Astrophysics Data System (ADS)

Thermoelectric (TE) materials and modules are important components of vehicle exhaust power-generation systems. The road and the engine, the main sources of vibration of TE modules, have substantial effects on the vibration characteristics of TE modules. In this work, modal analysis and the vibration characteristics of TE modules were investigated in detail. On the basis of the TE modules and their service environment, simulations for modal analysis were performed by use of the finite-element method, and the natural frequencies and mode shapes of the TE modules were obtained. The numerical results were used to compare the natural frequencies of TE modules under different contact stiffness with the range of excitation frequencies of road and engine, in an attempt to prevent severe resonance. The effects on the vibration characteristics of geometric dimensions, service temperature, and thermal stress of the TE modules are also discussed in detail. The results reveal the vibration characteristics of the TE modules and provide theoretical guidance for structure optimization in the design of vehicle exhaust power-generation systems.

Chen, Gang; Mu, Yu; Zhai, Pengcheng; Yu, Rui; Li, Guodong; Zhang, Qingjie

2014-06-01

290

NASA Astrophysics Data System (ADS)

A mass-spring-damper system is at the core of both a vibration absorber and a harvester of energy from ambient vibrations. If such a device is attached to a structure that has a high impedance, then it will have very little effect on the vibrations of the structure, but it can be used to convert mechanical vibrations into electrical energy (act as an energy harvester). However, if the same device is attached to a structure that has a relatively low impedance, then the device may attenuate the vibrations as it may act as both a vibration absorber and an energy harvester simultaneously. In this paper such a device is discussed. Two situations are considered; the first is when the structure is excited with broadband random excitation and the second is when the structure is excited by a single frequency. The optimum parameters of the device for both energy harvesting and vibration attenuation are discussed for these two cases. For random excitation it is found that if the device is optimized for vibration suppression, then this is also adequate for maximizing the energy absorbed (harvested), and thus a single device can effectively suppress vibration and harvest energy at the same time. For single frequency excitation this is found not to be the case. To maximize the energy harvested, the natural frequency of the system (host structure and absorber) has to coincide with the forcing frequency, but to minimize vibration of the host structure, the natural frequency of the absorber has to coincide with the forcing frequency. In this case, therefore, a single resonator cannot effectively suppress vibration and harvest energy at the same time.

Brennan, M. J.; Tang, B.; Melo, G. Pechoto; Lopes, V.

2014-02-01

291

V-V energy transfer from high vibrational levels of propynal

Results on infrared multiphoton absorption in propynal in which changes in the vibrational populations of ..nu../sub 6/ (v = 1,2) and ..nu../sub 10/ (v = 1,2) pumped under molecular beam or fast flow conditions were observed and reported recently. By producing a vibrationally excited beam of propynal and allowing for subsequent collisions with added gas molecules, it was possible to study V-V energy transfer processes which occur on a time scale less than or equal to gas kinetic. Relative cross sections for energy transfer from high vibrational levels were measured directly for the first time using visible - IR double resonance in a molecular beam - gas experiment. The process can be described by the general equation, C/sub 3/H/sub 2/O (v > 1) + M ..-->.. C/sub 3/H/sub 2/O (v = 1) + M + ..delta..E.

Brenner, D M

1980-01-01

292

NASA Astrophysics Data System (ADS)

A pump-probe experiment was performed to examine vibrational population relaxation of diiodomethane (CH 2I 2) molecule dissolved in supercritical CO 2. Using an apparatus with femtosecond time resolution, we observed the contributions of intramolecular vibrational energy redistribution (IVR) and intermolecular vibrational energy transfer (VET) separately. IVR and VET rates were measured with varying solvent densities at a constant temperature. It is shown that the IVR rate is not density dependent while the VET rate increases with increasing density from 0.4 to 0.8 g cm-3. This observation suggests that the rate of the VET process is determined by solute-solvent collisions whereas the IVR rate is not much affected by solute-solvent interaction.

Sekiguchi, K.; Shimojima, A.; Kajimoto, O.

2002-04-01

293

NASA Astrophysics Data System (ADS)

A mismatch between the ambient frequency and the resonant frequency of the vibrational energy harvester causes decrease of the energy transduction efficiency. Therefore, there is a great demand for the resonant frequency tuning of the vibrational energy harvester. In this paper, a flexible PVDF (polyvinylidene fluoride) cantilever, which can switch its resonant frequency automatically and maintain the switched resonant frequency without energy consumption, is proposed. The proposed energy harvester is composed of cantilever couples which are similar with a seesaw structure. When the proposed energy harvester is excited by an external vibration and the excited frequency fluctuates, the cantilever couples can be horizontally moved by using the large deflection of a flexible cantilever. So the beam length of each cantilever which corresponds to each arm of the seesaw structure can be changed and the resonant frequency of the proposed energy harvester can be switched in real time. The proposed energy harvester was realized by application of a piezoelectric polymer, PVDF. Also, it was confirmed that the proposed energy harvester can switch its resonant frequency in several seconds without an additional energy source.

Jo, Sung-Eun; Kim, Myoung-Soo; Kim, Yong-Jun

2012-01-01

294

NASA Astrophysics Data System (ADS)

This paper reports on an electrostatic Vibration Energy Harvester (e-VEH) system, for which the energy conversion process is initiated with a low bias voltage and is compatible with wideband stochastic external vibrations. The system employs the auto-synchronous conditioning circuit topology with the use of a novel dedicated integrated low-power high-voltage switch that is needed to connect the charge pump and flyback - two main parts of the used conditioning circuit. The proposed switch is designed and implemented in AMS035HV CMOS technology. Thanks to the proposed switch device, which is driven with a low-voltage ground-referenced logic, the e-VEH system may operate within a large voltage range, from a pre-charge low voltage up to several tens volts. With such a high-voltage e-VEH operation, it is possible to obtain a strong mechanical coupling and a high rate of vibration energy conversion. The used transducer/resonator device is fabricated with a batch-processed MEMS technology. When excited with stochastic vibrations having an acceleration level of 0.8 g rms distributed in the band 110-170 Hz, up to 0.75 ?W of net electrical power has been harvested with our system. This work presents an important milestone in the challenge of designing a fully integrated smart conditioning interface for the capacitive e-VEHs.

Dudka, A.; Basset, P.; Cottone, F.; Blokhina, E.; Galayko, D.

2013-12-01

295

Careers in Geothermal Energy: Power from below

ERIC Educational Resources Information Center

In the search for new energy resources, scientists have discovered ways to use the Earth itself as a valuable source of power. Geothermal power plants use the Earth's natural underground heat to provide clean, renewable energy. The geothermal energy industry has expanded rapidly in recent years as interest in renewable energy has grown. In 2011,…

Liming, Drew

2013-01-01

296

NASA Astrophysics Data System (ADS)

While environmental vibrations are usually in the range of a few hundred Hertz, small-form-factor piezoelectric vibration energy harvesters will have higher resonant frequencies due to the structural size effect. To address this issue, we propose a resonant frequency-down conversion based on the theory of dynamic vibration absorber for the design of a small-form-factor piezoelectric vibration energy harvester. The proposed energy harvester consists of two frequency-tuned elastic components for lowering the first resonant frequency of an integrated system but is so configured that an energy harvesting beam component is inverted with respect to the other supporting beam component for a small form factor. Furthermore, in order to change the unwanted modal characteristic of small separation of resonant frequencies, as is the case with an inverted configuration, a proof mass on the supporting beam component is slightly shifted toward a second proof mass on the tip of the energy harvesting beam component. The proposed small-form-factor design capability was experimentally verified using a fabricated prototype with an occupation volume of 20 × 39 × 6.9 mm3, which was designed for a target frequency of as low as 100 Hz.

Sun, Kyung Ho; Kim, Young-Cheol; Kim, Jae Eun

2014-10-01

297

While environmental vibrations are usually in the range of a few hundred Hertz, small-form-factor piezoelectric vibration energy harvesters will have higher resonant frequencies due to the structural size effect. To address this issue, we propose a resonant frequency-down conversion based on the theory of dynamic vibration absorber for the design of a small-form-factor piezoelectric vibration energy harvester. The proposed energy harvester consists of two frequency-tuned elastic components for lowering the first resonant frequency of an integrated system but is so configured that an energy harvesting beam component is inverted with respect to the other supporting beam component for a small form factor. Furthermore, in order to change the unwanted modal characteristic of small separation of resonant frequencies, as is the case with an inverted configuration, a proof mass on the supporting beam component is slightly shifted toward a second proof mass on the tip of the energy harvesting beam component. The proposed small-form-factor design capability was experimentally verified using a fabricated prototype with an occupation volume of 20 × 39 × 6.9 mm{sup 3}, which was designed for a target frequency of as low as 100 Hz.

Sun, Kyung Ho; Kim, Young-Cheol [Department of System Dynamics, Korea Institute of Machinery and Materials, 156 Gajeongbuk-Ro, Yuseong-Gu, Daejeon 305-343 (Korea, Republic of); Kim, Jae Eun, E-mail: jekim@cu.ac.kr [School of Mechanical and Automotive Engineering, Catholic University of Daegu, 13-13 Hayang-Ro, Hayang-Eup, Gyeongsan-Si, Gyeongsangbuk-Do 712-702 (Korea, Republic of)

2014-10-15

298

Study of vibrational energy localization and redistribution in hydrogen peroxide H2O2 at low energy

Study of vibrational energy localization and redistribution in hydrogen peroxide H2O2 at low energy in hydrogen peroxide H2O2 is studied at about 4000 cm-1 above the quantum mechanical ground state using the ab contributes to this effort by presenting a study of IVR in hydrogen peroxide H2O2 at about 4000 cm-1 above

299

Near-resonant vibration. -->. vibration energy transfer under single-collision conditions. [Propynal

Energy transfer in single collisions of propynal (HC triple bond C-CHO) subsequent to ir multiphonon absorption (CO/sub 2/ laser) was studied. SiF/sub 4/, CH/sub 3/F, CCl/sub 4/, and CH/sub 4/ were added. (DLC)

Breener, D M

1981-01-01

300

Free energy and vibrational entropy difference between ordered and disordered Ni3Al

We have calculated free energy and vibrational entropy differences in Ni3Al between its equilibrium ordered structure and a disordered fcc solid solution. The free energy and entropy differences were calculated using the method of adiabatic switching in a molecular-dynamics formalism. The path chosen for the free-energy calculations directly connects the disordered with the ordered state. The atomic interactions are described

R. Ravelo; J. Aguilar; M. Baskes; J. E. Angelo; B. Fultz; Brad Lee Holian

1998-01-01

301

High-level ab initio potential energy surfaces and vibrational energies of H2CS.

Six-dimensional (6D) potential energy surfaces (PESs) of H(2)CS have been generated ab initio using the recently proposed explicitly correlated (F12) singles and doubles coupled cluster method including a perturbational estimate of connected triple excitations, CCSD(T)-F12b [T. B. Adler, G. Knizia, and H.-J. Werner, J. Chem. Phys. 127, 221106 (2007)] in conjunction with F12-optimized correlation consistent basis sets. Core-electron correlation, high-order correlation, scalar relativistic, and diagonal Born-Oppenheimer terms were included as additive high-level (HL) corrections. The resulting 6D PESs were represented by analytical functions which were used in variational calculations of the vibrational term values below 5000 cm(-1). The best PESs obtained with and without the HL corrections, VQZ-F12(*HL) and VQZ-F12?, reproduce the fundamental vibrational wavenumbers with mean absolute deviations of 1.13 and 1.22 cm(-1), respectively. A detailed analysis of the effects of the HL corrections shows how the VQZ-F12 results benefit from error cancellation. The present purely ab initio PESs will be useful as starting points for empirical refinements towards an accurate "spectroscopic" PES of H(2)CS. PMID:21861565

Yachmenev, Andrey; Yurchenko, Sergei N; Ribeyre, Tristan; Thiel, Walter

2011-08-21

302

NASA Astrophysics Data System (ADS)

A new global approach for improved vibration damping of smart structure, based on global energy redistribution by means of a network of piezoelectric elements is proposed. It is basically using semi-active Synchronized Switch Damping technique. SSD technique relies on a cumulative build-up of the voltage resulting from the continuous switching and it was shown that the performance is strongly related to this voltage. The increase of the piezoelectric voltage results in improvement of the damping performance. External voltage sources or improved switching sequences were previously designed to increase this voltage in the case of single piezoelectric element structure configurations. This paper deals with extended structure with many embedded piezoelectric elements. The proposed strategy consist of using an electric network made with non-linear component and switches in order to set up and control a low-loss energy transfer from source piezoelements extracting the vibration energy of the structure and oriented toward a given piezoelement in order to increase its operative energy for improving a given mode damping. This paper presents simulation of a clamped plate with four piezoelectric elements implemented in the Matlab/SimulinkTM environment and SimscapeTM library. The various simulation cases show the relationship between the damping performance on a given targeted mode and the established power flow. SSDD and SSDT are two proposed original networks. Performances are compared to the SSDI baseline. A damping increase of 18dB can be obtained even with a weakly coupled piezoelectric element in the multi-sine excitation case. This result proves the importance of new global non-linear multi-actuator strategies for improved vibration damping of extended smart structure.

Wu, Dan; Guyomar, Daniel; Richard, Claude

2013-04-01

303

Although wheelchair users are frequently subjected to oscillatory and shock vibrations, little research has been conducted to assess the whole-body vibration exposure of wheelchair users. The purpose of this study was to determine if selected wheelchair cushions alter potentially harmful whole-body vibrations transferred to wheelchair users. Thirty-two participants, who use wheelchairs as their primary mode of mobility, contributed to this study. Four of the most commonly prescribed wheelchair cushions were selected. Participants were asked to propel their wheelchair over a simulated activities of daily living (ADL) course while acceleration and force data were recorded. A repeated measures ANOVA showed no significant differences between the different cushions for the total averaged absorbed power (p = 0.190), the 50 mm curb drop (p = 0.234), or the rumble strip (p = 0.143). A repeated measure ANOVA for the peak curb drop absorbed power revealed a significant difference in the cushions (p = 0.043). The cushions that were most effective in this testing appear to be the Invacare Pindot and the Varilite Solo. Not only did those cushions appear to have the lowest values much of the time but also they did not display the highest values. When comparing results from a similar study, absorbed power appears to be as effective in determining vibration effects in the time domain as the methods in the ISO 2631 Standard. PMID:15564117

Wolf, Erik J; Cooper, M S Rory A; DiGiovine, Carmen P; Boninger, Michael L; Guo, Songfeng

2004-11-01

304

Accurate ab initio potential energy curve of F2. III. The vibration rotation spectrum

NASA Astrophysics Data System (ADS)

An analytical expression is found for the accurate ab initio potential energy curve of the fluorine molecule that has been determined in the preceding two papers. With it, the vibrational and rotational energy levels of F2 are calculated using the discrete variable representation. The comparison of this theoretical spectrum with the experimental spectrum, which had been measured earlier using high-resolution electronic spectroscopy, yields a mean absolute deviation of about 5cm-1 over the 22 levels. The dissociation energy with respect to the lowest vibrational energy is calculated within 30cm-1 of the experimental value of 12953±8cm-1. The reported agreement of the theoretical spectrum and dissociation energy with experiment is contingent upon the inclusion of the effects of core-generated electron correlation, spin-orbit coupling, and scalar relativity. The Dunham analysis [Phys. Rev. 41, 721 (1932)] of the spectrum is found to be very accurate. New values are given for the spectroscopic constants.

Bytautas, L.; Matsunaga, N.; Nagata, T.; Gordon, M. S.; Ruedenberg, K.

2007-11-01

305

Speech synthesis using a nonlinear energy damping model for the vocal folds vibration effect

From a theoretical viewpoint, the vocal folds vibration affectsthe vocal tract transfer characteristics through nonlineartime-varying interaction between the glottis and vocaltract. Therefore, it is crucial to investigate and modelsuch effects in order to improvevoice quality in parametricrule-based speech synthesis systems. In this paper, we firstconducted analytic experiments on the vocal folds vibrationeffects on the appeared in formant energy damping patternsand

Hiroshi Ohmura; Kazuyo Tanaka

1996-01-01

306

Oscillator strengths, HuangÂRhys parameters, and vibrational quantum energies of cerium absorption of cerium-doped gadolinium oxyorthosilicate (Gd2SiO5:Ce) has been measured and analyzed for impurity-ion-lattice coupling parameters and oscillator strengths. Although the spectrum consists

307

Alternative Energy and Remote Power Products

NSDL National Science Digital Library

Based in Alaska, ABS Alaskan provides batteries, alternative energy and remote and power products. The site contains a Library link, where users can explore a basic power system diagram, visit the document download center, and find information explaining alternative energy and power systems.

2008-09-30

308

A transformation of potential energy surfaces (PES) being represented by multi-mode expansions is introduced, which allows for the calculation of anharmonic vibrational spectra of any isotopologue from a single PES. This simplifies the analysis of infrared spectra due to significant CPU-time savings. An investigation of remaining deviations due to truncations and the so-called multi-level approximation is provided. The importance of vibrational-rotational couplings for small molecules is discussed in detail. In addition, an analysis is proposed, which provides information about the quality of the transformation prior to its execution. Benchmark calculations are provided for a set of small molecules. PMID:24832257

Meier, Patrick; Oschetzki, Dominik; Berger, Robert; Rauhut, Guntram

2014-05-14

309

A transformation of potential energy surfaces (PES) being represented by multi-mode expansions is introduced, which allows for the calculation of anharmonic vibrational spectra of any isotopologue from a single PES. This simplifies the analysis of infrared spectra due to significant CPU-time savings. An investigation of remaining deviations due to truncations and the so-called multi-level approximation is provided. The importance of vibrational-rotational couplings for small molecules is discussed in detail. In addition, an analysis is proposed, which provides information about the quality of the transformation prior to its execution. Benchmark calculations are provided for a set of small molecules.

Meier, Patrick; Oschetzki, Dominik; Rauhut, Guntram, E-mail: rauhut@theochem.uni-stuttgart.de [Institut für Theoretische Chemie, Universität Stuttgart, Pfaffenwaldring 55, 70569 Stuttgart (Germany)] [Institut für Theoretische Chemie, Universität Stuttgart, Pfaffenwaldring 55, 70569 Stuttgart (Germany); Berger, Robert [Clemens-Schöpf Institut für Organische Chemie and Biochemie, Technische Universität Darmstadt, Petersenstrasse 22, 64287 Darmstadt (Germany)] [Clemens-Schöpf Institut für Organische Chemie and Biochemie, Technische Universität Darmstadt, Petersenstrasse 22, 64287 Darmstadt (Germany)

2014-05-14

310

The large-amplitude, low-frequency vibrations of vinylene carbonate and 1,3-cyclohexadiene in the vapor phase were analyzed by far-infrared spectroscopy, and the vibrational potential energy surfaces which govern their conformational structures were determined. For vinylene carbonate several sharp bands resulting from the ring-puckering vibration were observed near 230 cm-1, and these were fitted using the single minimum potential function V(cm-1) = 1.65

Daniel Autrey; Arnold del Rosario; Jaebum Choo; Jaan Laane

1999-01-01

311

Power electronics in wind energy conversion systems

This paper presents a brief review of the power electronics techniques used in wind energy conversion systems. Utilization of power electronics converters enables conversion of the generated power from any form to another and thus control the operation quality and obtain capture optimization. Attention is paid to power converters selection and design to satisfy good matching between generator type and

FAEKA M. H. KHATER

1996-01-01

312

NASA Technical Reports Server (NTRS)

A bearing damper, operating on the support flexure of a pivoted pad in a tilting-pad type gas-lubricated journal bearing, has been designed, built, and tested under externally-applied random vibrations. The NASA Brayton Rotating Unit (BRU), a 36,000 rpm, 10-Kwe turbogenerator had previously been subjected in the MTI Vibration Test Laboratory to external random vibrations, and vibration response data had been recorded and analyzed for amplitude distribution and frequency content at a number of locations in the machine. Based on data from that evaluation, a piston-type damper was designed and developed for each of the two flexibly-supported journal bearing pads (one in each of the two three-pad bearings). A modified BRU, with dampers installed, has been re-tested under random vibration conditions. Root-mean-square vibration amplitudes were determined from the test data, and displacement power spectral density analyses have been performed. Results of these data reduction efforts have been compared with vibration tolerance limits. Results of the tests indicate significant reductions in vibration levels in the bearing gas-lubricant films, particularly in the rigidly-mounted pads. The utility of the gas-lubricated damper for limiting rotor-bearing system vibrations in high-speed turbomachinery has thus been demonstrated.

Tessarzik, J. M.; Chiang, T.; Badgley, R. H.

1974-01-01

313

NASA Astrophysics Data System (ADS)

The deexcitation of HCl(v) by HCl(0) for v=1-4 is shown to undergo vibration-to-vibration (V-V) energy exchange with the transfer of the energy mismatch ?E through rotation (R) and translation (T). When v is small, the translational motion plays a major role in transferring ?E, but when v is large, the rotational motion is of major importance in supplying ?E. The sum of V-V, T and V-V, R contributions are in reasonable agreement with observed data at 300 K. For v?4, the V-V mechanism appears to underestimate deexcitation probabilities seriously.

Shin, H. K.

1983-01-01

314

Vibration energy harvesting using the nonlinear oscillations of a magnetostrictive material

NASA Astrophysics Data System (ADS)

A novel magnetostrictive-material-based device concept to convert ambient mechanical vibration into electricity has been designed, fabricated, and tested. In order to harvest energy over a greater frequency range as compared to state-of- the-art devices, an L-shaped beam which is tuned so that the first two (bending) natural frequencies have a (near) two-to-one ratio is used as a mechanical transducer to generate nonlinear oscillations. Under harmonic excitation, an internal resonance or autoparametric, dynamic response can occur in which one vibration mode parametrically excites a second vibration mode resulting in significant displacement of both modes over an extended frequency range. A magnetostrictive material, Metglas 2605SA1, is used to convert vibration into electricity. Vibration-induced strain in the Metglas changes its magnetization which in turn generates current in a coil of wire. Metglas is highly flexible so it can undergo large displacement and does not fatigue under extended excitation. Demonstration devices are used to study how this nonlinear response can be exploited to generate electricity under single-frequency, harmonic and random base excitation.

Tsutsumi, Erika; del Rosario, Zachary; Lee, Christopher

2012-04-01

315

Effects of Collision and Vibrational Energy on the Reaction of CH3CHO+() with C2D4 Ho-Tae Kim mode effects on reaction, comparing the effects of reactant vibration and collision energy provides collision energy and vibrational effects, it is possible to separate partially the influences of complex

Anderson, Scott L.

316

Vibrational Energies for Acrylonitrile from Mm-Wave to Thz Rotational Spectra

NASA Astrophysics Data System (ADS)

The THz rotational spectrum of acrylonitrile has recently been studied in detail. The coverage of the ground state rotational transitions has been extended up to J=128, K_a=29 and it was found that at very high-J there are multiple manifestations of a perturbation between the ground state and the lowest vibrationally excited state, V11=1. The perturbation has been successfully fitted and the excited state energy determined at 228.29991(2) Cm-1, which turns out to be the largest energy difference between any two neighboring vibrational states of acrylonitrile. Extensive broadband rotational spectra of acrylonitrile have been recorded at JPL and at OSU and provide coverage from the mm-wave region up to well into the THz. The analysis of these spectra performed with the AABS package allowed identification of a ladder of pairwise perturbations extending from the ground state and connecting all successive low lying vibrational states. A global fit of all of the observed effects is expected to deliver accurate energies for the lowest vibrational states from only the rotational spectrum. The progress made towards achieving this goal is described. Z.Kisiel, L.Pszczó?kowski, B.J.Drouin, C.S.Brauer, S.Yu, J.C.Pearson, J. Mol. Spectrosc., 258, 26 (2009). Z.Kisiel, L.Pszczó?kowski, I.R.Medvedev, M.Winewisser, F.C.De Lucia, E.Herbst, J. Mol. Spectrosc., 233, 231 (2005).

Kisiel, Zbigniew; Pszczó?kowski, Lech; Drouin, Brian J.; Brauer, Carolyn S.; Yu, Shanshan; Pearson, John C.; Medvedev, Ivan R.; Fortman, Sarah; Neese, Christopher

2011-06-01

317

Power and Energy Management for Server Systems

Power and energy consumption are key concerns for Internet data centers. These centers house hun- dreds, sometimes thousands, of servers and supporting cooling infrastructures. Research on power and energy management for servers can ease data center installation, reduce costs, and protect the environ- ment. Given these benefits, researchers have made important strides in conserving energy in servers. Inspired by this

Ricardo Bianchini; Ramakrishnan Rajamony

2004-01-01

318

NASA Astrophysics Data System (ADS)

Dissociative adsorption of methane has been investigated on Pd {1 1 0} by using molecular beam surface scattering. The initial sticking probability has been determined in the translational energy range of 7-95 kJ/mol and at selected vibrational energies from 300 to 700 K. The measured initial sticking probability is found to increase strongly with both translational and vibrational energy of CH 4 molecules. The activation of the dissociative chemisorption of CH 4 induced by the vibrational energy is shown to depend on the translational energy and is attributed to the excitation of the bending modes of the incident molecule. We have also performed molecular dynamics simulations to investigate the dissociation mechanism theoretically. The simulations clearly demonstrate that an efficient energy transfer occurs upon adsorption between the translational and vibrational energies of the incident CH 4 molecule, which thereby facilitates the deformation of the molecular structure of CH 4 resulting in dissociation.

Hirsimäki, M.; Paavilainen, S.; Nieminen, J. A.; Valden, M.

2001-06-01

319

Quantum mechanical model of vibrational-electronic energy exchange during collisions

A model for the interchange of energy between an electronic and a vibrational mode during a collinear atom--molecule collision is proposed. Although crude, the model is simple enough to be solved exactly using the R-matrix propagator method for treating quantum close-coupling problems. These exact results can be compared to semiclassical and approximate treatments of the same problem. Several interesting features of the model system are discussed in terms of elementary energy transfer concepts.

Schmalz, T.G.

1982-02-15

320

Power marketing and renewable energy

Power marketing refers to wholesale and retail transactions of electric power made by companies other than public power entities and the regulated utilities that own the generation and distribution lines. The growth in power marketing has been a major development in the electric power industry during the last few years, and power marketers are expected to realize even more market opportunities as electric industry deregulation proceeds from wholesale competition to retail competition. This Topical Issues Brief examines the nature of the power marketing business and its relationship with renewable power. The information presented is based on interviews conducted with nine power marketing companies, which accounted for almost 54% of total power sales by power marketers in 1995. These interviews provided information on various viewpoints of power marketers, their experience with renewables, and their respective outlooks for including renewables in their resource portfolios. Some basic differences exist between wholesale and retail competition that should be recognized when discussing power marketing and renewable power. At the wholesale level, the majority of power marketers stress the commodity nature of electricity. The primary criteria for developing resource portfolios are the same as those of their wholesale customers: the cost and reliability of power supplies. At the retail level, electricity may be viewed as a product that includes value-added characteristics or services determined by customer preferences.

Fang, J.M.

1997-09-01

321

Second Proof Work, Power, and Energy

and minimal impact on the environment. energy conversion A process of transformation of one form of energy) energy sources, such as solar energy, wind, water flows, ocean and tidal waves, and biomassSecond Proof Work, Power, and Energy M. KOSTIC Northern Illinois University DeKalb, Illinois

Kostic, Milivoje M.

322

Enhanced output power by eigenfrequency shift in acoustic energy harvester

NASA Astrophysics Data System (ADS)

In our previous studies, multiple piezoelectric cantilever plates were placed inside a quarter-wavelength straight tube resonator to harvest low frequency acoustic energy. To investigate the modification of eigenmodes in the tube resonator due to the presence of piezoelectric plates, the eigenfrequency shift properties by introducing single and multiple rectangular blockages in open-closed ducts are studied by using 1D segmented Helmholtz equations, Webster horn equation, and finite element simulations. The first-mode eigenfrequency of the duct is reduced when the blockage is placed near the open inlet. The decrease of eigenfrequency leads to the enhancement of absorbed acoustic power in the duct. Furthermore, the first half of the tube resonator possesses high pressure gradient resulting in larger driving forces for the vibration motion of piezoelectric plates. Therefore, in our harvesters, it is better to place the piezoelectric plates in the first half of the tube resonator to obtain high output voltage and power.

Li, Bin; You, Jeong Ho

2014-04-01

323

A power conditioning system with energy storage capability is proposed as a viable solution for improving the quality and the reliability of the electric energy supply. Several tasks can be performed at the same time, such as reactive power compensation, current harmonic reduction, and smoothing of pulsating loads. Moreover, the power conditioning system can operate as an uninterruptible power supply

D. Casadei; G. Grandi; G. Serra; C. Rossi

2005-01-01

324

NASA Astrophysics Data System (ADS)

We propose a phenomenon of piezoelectrochemical (PZEC) effect for the direct conversion of mechanical energy to chemical energy. This phenomenon is further applied for generating hydrogen and oxygen via direct water decomposition by means of as-synthesized piezoelectric quartz (SiO2) nano-rods, ZnO microfibers, and BaTiO3 microdendrites. The materials are vibrated with ultrasonic waves leading to a strain-induced electric charge development on their surface. With sufficient electric potential, the strained piezoelectric materials in water triggered the redox reaction of water to produce hydrogen and oxygen gases. All materials have indicated a well response to the external mechanical vibration to drive the desired chemical reactions. ZnO fibers under ultrasonic vibrations showed a stoichiometric ratio of H 2/O2 (2:1) initial gas production from pure water. The efficiency of the piezoelectrochemical effect was calculated by ratio of the chemical energy output over the mechanical energy input of the system. The study of piezoelectrochemical effect is further applied to the environmental cleaning technology. Accordingly, a dissolved orange dye (AO7) was decomposed via mechanical driving force by using BaTiO3 microdendrites. Kinetic details of the dye decomposition through piezoelectrochemical effect were investigated. In addition, the piezoelectrochemical effect was proposed to the implication of tectonic hydrogen in geological systems providing insights of hydrogen generation in active fault zones. The tectonic hydrogen produced through PZEC effect could be a sustainable energy source for subsurface microbial community. This study provides a simple and cost-effective technology for generating hydrogen fuels as well as environmental cleaning by scavenging energy wastes such as noise or stray vibrations from the environment. This new piezoelectrochemical effect may have potential implications in solving the challenging energy and environmental issues that we are facing today and in the future.

Hong, Kuang-Sheng

325

Estimating the vibration level of an L-shaped beam using power flow techniques

NASA Technical Reports Server (NTRS)

The response of one component of an L-shaped beam, with point force excitation on the other component, is estimated using the power flow method. The transmitted power from the source component to the receiver component is expressed in terms of the transfer and input mobilities at the excitation point and the joint. The response is estimated both in narrow frequency bands, using the exact geometry of the beams, and as a frequency averaged response using infinite beam models. The results using this power flow technique are compared to the results obtained using finite element analysis (FEA) of the L-shaped beam for the low frequency response and to results obtained using statistical energy analysis (SEA) for the high frequencies. The agreement between the FEA results and the power flow method results at low frequencies is very good. SEA results are in terms of frequency averaged levels and these are in perfect agreement with the results obtained using the infinite beam models in the power flow method. The narrow frequency band results from the power flow method also converge to the SEA results at high frequencies. The advantage of the power flow method is that detail of the response can be retained while reducing computation time, which will allow the narrow frequency band analysis of the response to be extended to higher frequencies.

Cuschieri, J. M.; Mccollum, M.; Rassineux, J. L.; Gilbert, T.

1986-01-01

326

Quantum localization and protein-assisted vibrational energy flow in cofactors

NASA Astrophysics Data System (ADS)

Quantum effects influence vibrational dynamics and energy flow in biomolecules, which play a central role in biomolecule function, including control of reaction kinetics. Lifetimes of many vibrational modes of proteins and their temperature dependence, as determined by quantum golden-rule-based calculations, exhibit trends consistent with experimental observation and distinct from estimates based on classical modeling. Particularly notable are quantum coherence effects that give rise to localization of vibrational states of sizable organic molecules in the gas phase. Even when such a molecule, for instance a cofactor, is embedded in a protein, remnants of quantum localization survive that influence vibrational energy flow and its dependence on temperature. We discuss these effects on the mode-damping rates of a cofactor embedded in a protein, using the green fluorescent protein chromophore as a specific example. We find that for cofactors of this size embedded in their protein and solvent environment at room temperature a golden-rule calculation often overestimates the mode-damping rate.

Leitner, David M.

2010-08-01

327

Laboratory Measurement of O3(v) + O Vibrational Energy Transfer

NASA Astrophysics Data System (ADS)

Photochemical reactions involving O3 play a key role in determining the thermal and radiative structure of the upper mesosphere/lower thermosphere. Emission detected in NASA's TIMED/SABER 9.6-?m channel is dominated by the O3(?3) asymmetric stretch mode, including hot band and combination band emission arising from vibrationally-excited O3(v) populated by O + O2 + M three-body recombination. Rate coefficients kM(O3) for the relaxation of O3(v) by O2, N2, and O must be known to confidently model the O3 photochemistry in this region. Measurements of O3( v) quenching by O2 and N2 have been performed by several groups, including the temperature dependence. On the other hand, rate coefficients kO(O3) for quenching of O3(?2,?3) by O were only reported in a single published paper some 30 years ago. Those measurements were performed at room temperature, and yielded rate coefficients with factor-of-two precision. The data suggest that quenching of O3(v) by O could make a significant contribution especially at higher altitudes, motivating an updated measurement. The goal of the present work is to measure the quenching of several excited O3(v) levels by O using a temperature-jump/transient diode laser absorption experiment similar to the ongoing CO2(?2)-O study. Ultimately a variable-temperature reaction cell will be used to measure temperature-dependent O3(v)-O relaxation rates for the first time.

Castle, K. J.; Hwang, E. S.; Dodd, J. A.

2007-12-01

328

A new vibrational subsystem analysis (VSA) method is presented for coupling global motion to a local subsystem while including the inertial effects of the environment. The premise of the VSA method is a partitioning of a system into a smaller region of interest and a usually larger part referred to as environment. This method allows the investigation of local-global coupling, a more accurate estimation of vibrational free energy contribution for parts of a large system, and the elimination of the “tip effect” in elastic network model calculations. Additionally, the VSA method can be used as a probe of specific degrees of freedom that may contribute to free energy differences. The VSA approach can be employed in many ways, but it will likely be most useful for estimating activation free energies in QM?MM reaction path calculations. Four examples are presented to demonstrate the utility of this method. PMID:19063546

Woodcock, H. Lee; Zheng, Wenjun; Ghysels, An; Shao, Yihan; Kong, Jing; Brooks, Bernard R.

2008-01-01

329

Vibrational energy transfer at a gold surface in reacting systems: cyclobutene and nitromethane

Single collision excitation probabilities were measured for cyclobutene and nitromethane on seasoned polycrystalline gold plane and wire surfaces. Transport above the reaction thresholds for isomerization and decomposition, respectively, for the two substrates was used as the criterion of vibrational energy transfer. Several different seasoning and processing procedures of the surfaces were employed. For cyclobutene, a decreased efficiency relative to strong collider transition probabilities appeared only above 550-600 K; the energy transfer efficiency at a treated gold surface is greater than that at a seasoned silica surface. The vibrational energy transfer efficiency declined above 600 K and fell abruptly to a quasiconstant value in the range 900-1100 K. Above 1100 K the differences between various conditioned surfaces diminished progressively. Unlike cyclobutene, and earlier studies of nitromethane on silica surfaces where reproducible noncatalytic behavior could be attained, nitromethane on gold showed apparent catalytic behavior which the various conditioning treatments failed to repress.

Yuan, W.; Rabinovitch, B.S.

1983-06-09

330

NASA Astrophysics Data System (ADS)

Vibrational energy transfer from the first excited state (2252 cm-1) of the C-D stretch of deuterated chloroform (DCCl3) to the 0-1 transition (2155 cm-1) of the CN stretch of phenyl selenocyanate (C6H5SeCN) in their 1:1 liquid mixture was observed with a pump/probe two-color two dimensional infrared spectroscopic technique. The mode-specific energy transfer can occur mainly because of the long vibrational lifetime of the CN stretch first excited state (˜300 ps) and the relatively strong hydrogen-bond between the C-D and CN (calculated H-bond formation energy in gas phase ˜-5.4 kcal/mol). The mode-specific energy transfer is relatively low efficient (only ˜2%), which is mainly because of the relatively short vibrational lifetime (˜9 ps) of the C-D stretch first excited state and the big donor/acceptor energy mismatch (97 cm-1) and the slow transfer kinetics (1/kCD?CN=330 ps).

Bian, Hongtao; Li, Jiebo; Wen, Xiewen; Zheng, Junrong

2010-05-01

331

On the nature of intramolecular vibrational energy transfer in dense molecular environments

NASA Astrophysics Data System (ADS)

Transient femtosecond-IR-pump-UV-absorption probe-spectroscopy has been employed to shed light on the nature of intramolecular vibrational energy transfer (IVR) in dense molecular environments ranging from the diluted gas phase to the liquid. A general feature in our experiments and those of others is that IVR proceeds via multiple timescales if overtones or combination vibrations of high frequency modes are excited. It has been found that collisions enhance IVR if its (slower) timescales can compete with collisions. This enhancement is, however, much more weaker and rather inefficient as opposed to the effect of collisions on intermolecular energy transfer which is well known. In a series of experiments we found that IVR depends not significantly on the average energy transferred in a collision but rather on the number of collisions. The collisions are much less efficient in affecting IVR than VET. We conclude that collision induced broadening of vibrational energy levels reduces the energy gaps and enhances existing couplings between tiers. The present results are an important step forward to rationalize and understand apparently different and not consistent results from different groups on different molecular systems between gas and liquid phases.

von Benten, Rebekka S.; Abel, Bernd

2010-12-01

332

Diagnosis of Centrifugal Pump Faults Using Vibration Methods

Pumps are the largest single consumer of power in industry. This means that faulty pumps cause a high rate of energy loss with associated performance degradation, high vibration levels and significant noise radiation. This paper investigates the correlations between pump performance parameters including head, flow rate and energy consumption and surface vibration for the purpose of both pump condition monitoring

A Albraik; F Althobiani; F Gu; A Ball

2012-01-01

333

NASA Astrophysics Data System (ADS)

State-to-state branching ratios are reported for vibrational energy transfer (VET) from the 30 2 and 8 2 vibrational levels in S 1 ( 1B 2u) p-difluorobenzene by the collision partners He and Ar in the collision region of a supersonic free-jet expansion. For VET from the 8 2 level, He removes more energy than does Ar. This is the expected light collision partner effect. For the 30 2 level, however, Ar unexpectedly removes more energy than He. The opposing behaviour observed for relaxation by He and Ar from two vibrational levels of the same molecule is inconsistent with a universal 'light collision partner effect'.

Mudjijono; Lawrence, Warren D.

1994-06-01

334

Energy function analysis for power system stability

Energy Function Analysis for Power System Stability presents the concept of energy function, which has found wide-spread applications for power systems in recent years. The most recent advances in five distinct areas are reviewed: Development of energy functions for structure preserving models, which can incorporate non-linear load models; energy functions which include a detailed model of the generating unit (i.e.

M. A. Pai

1989-01-01

335

We report the results of calibration of an optical-fibre (OF) probe designed for interferometric measurement of vibrations inside high-power transformers. The sensor is highly sensitive in this harsh environment of electromagnetic fields, wide temperature range and oil immersion. A comparative analysis with commercial piezoelectric accelerometers is also presented, focusing on two experiments: the common calibration with a free-space Michelson interferometer

J. A. García-Souto; H. Lamela-Rivera

2002-01-01

336

Vibrational and collision energy effects on the reaction of CH3CHO+ with methanol

NASA Astrophysics Data System (ADS)

Integral cross sections and product velocity distributions were measured for reaction of acetaldehyde cation with methanol over a center-of-mass collision energy range from 0.1 to 2.2 eV. Reactivity is dominated by exoergic proton transfer (PT), which is strongly suppressed by collision energy, and mildly suppressed by CH3CHO+ vibrational excitation. PT is complex-mediated at low energies, switching to a direct stripping mechanism at high energies. Of the two possible PT channels, it appears that transfer of the aldehyde proton dominates. Hydrogen abstraction (HA) is a minor channel at low collision energies, also complex-mediated. Abstraction is observed from both hydroxyl and methyl sites on methanol, and the two channels have different, and counterintuitive collision energy dependence. Despite being exoergic, with no barriers, the HA channel shows apparent threshold behavior, attributed to competition with the dominant PT channel. The competition indicates that different intermediate complexes must interconvert efficiently, at least for low collision energies. At low energies, HA is strongly enhanced by collision energy, while vibrational excitation has no effect. Finally, there is a minor product channel corresponding to methyl elimination (ME) from a complex. Despite a relatively complicated reaction coordinate, the ME channel shows substantial recoil energy release and an asymmetric velocity distribution. A series of ab initio and RRKM calculations were performed to help interpret the results.

Kim, Ho-Tae; Liu, Jianbo; Anderson, Scott L.

2001-10-01

337

This book reports on dimensional analysis; ideal fluid models; vortex-induced vibration; galloping and flutter; instability of tube and cylinder arrays; vibrations induced by oscillating flow; vibration induced by turbulence and sound; damping of structures; sound induced by vortex shedding; vibrations of a pipe containing a fluid flow; indices. It covers the analysis of the vibrations of structures exposed to fluid flows; explores applications for offshore platforms and piping; wind-induced vibration of buildings, bridges, and towers; and acoustic and mechanical vibration of heat exchangers, power lines, and process ducting.

Blevins, R.D.

1990-01-01

338

NASA Astrophysics Data System (ADS)

This paper presents a small, high-performance and novel device that generates power from vibrations, made using screen-printing to form a piezoelectric thick film directly on a stainless steel substrate. This simple and cheap method realizes a 20 – 40 ?m-thick piezoelectric film, otherwise difficult to achieve using thin-film techniques or ceramic sintering, on a stainless steel substrate. A maximum output power of 1.1 mW was recorded with acceleration of 0.1 G0p (0.98 ms?2) applied at a resonance frequency of 24 Hz. We also evaluated the durability of the device by repeatedly striking the tip of the element. Output power exceeding 100 mW under damped resonant vibration was generated at the instant of striking, with approximately 0.9 mJ of power measured per single damped vibration. No deterioration was seen in the integrity of the stainless steel substrate or the piezoelectric thick film after over 10 million strikes.

Oishi, A.; Okumura, H.; Katsumura, H.; Kagata, H.

2014-11-01

339

NASA Astrophysics Data System (ADS)

A low-frequency vibration energy generator has been proposed by using a locally resonant phononic crystal plate which has spiral beams connecting the scatterers and the matrix. Finite element analysis shows that at the flat bands frequencies of the phononic crystal, locally resonant leads to the spiral beams having strong deformations which are perpendicular to the plate. A designed structure with three PC cells arranged in the same direction was adopted for the experiments. Piezoelectric patches were adhered on the end of the spiral beams and then the collected vibration energy could be converted into electric energy. The maximum single-channel output voltage which reached as much as 13 V was obtained at the first flat band frequency 29.2 Hz in the experiment. Meanwhile, in the low-frequency range of 0-500 Hz, it showed that the piezoelectric transformation could be conducted at a dozen of resonant frequencies. Furthermore, through modulating the structure parameters, this phononic crystal has the potential to realize broad-distributed vibration energy harvesting.

Shen, Li; Wu, Jiu Hui; Zhang, Siwen; Liu, Zhangyi; Li, Jing

2015-01-01

340

Nuclear Power Trends Energy Economics and Sustainability

Nuclear Power Trends Energy Economics and Sustainability L. H. Tsoukalas Purdue University Nuclear;National Research Council of Greece, May 8, 2008 Outline Â· The Problem Â· Nuclear Energy Trends Â· Energy Economics Â· Life Cycle Analysis Â· Nuclear Sustainability Â· Nuclear Energy in Greece? #12;National Research

341

Renewable Energy. The Power to Choose.

ERIC Educational Resources Information Center

This book, consisting of 13 chapters, charts the progress made in renewable energy in recent years and outlines renewable energy's prospects. Areas addressed include: energy at the crossroads (discussing oil, gas, coal, nuclear power, and the conservation revolution); solar building design; solar collection; sunlight to electricity; wood; energy…

Deudney, Daniel; Flavin, Christopher

342

Solar energy thermally powered electrical generating system

NASA Technical Reports Server (NTRS)

A thermally powered electrical generating system for use in a space vehicle is disclosed. The rate of storage in a thermal energy storage medium is controlled by varying the rate of generation and dissipation of electrical energy in a thermally powered electrical generating system which is powered from heat stored in the thermal energy storage medium without exceeding a maximum quantity of heat. A control system (10) varies the rate at which electrical energy is generated by the electrical generating system and the rate at which electrical energy is consumed by a variable parasitic electrical load to cause storage of an amount of thermal energy in the thermal energy storage system at the end of a period of insolation which is sufficient to satisfy the scheduled demand for electrical power to be generated during the next period of eclipse. The control system is based upon Kalman filter theory.

Owens, William R. (Inventor)

1989-01-01

343

with molecular hydrogen, simulating the conditions in an experimental study of H2CO+ vibrational effects experimental study of the effects of collision energy (Ecol) and reactant vibrational excitation that would be expected if the effect were proportional to vibrational energy. A similar pattern

Anderson, Scott L.

344

Vibrational and Translational Energy Effects in the Reaction of Ammonia Ions with Water Molecules of vibrationally state-selected ammonia ions with deuterated water is investigated with a quadrupole energies from 0.5 to 10.0 eV (center of mass) and ammonia ion vibrational states 1020-10 and 1122

Zare, Richard N.

345

Power electronics and alternative energy generation

Growth in alterative energy generation technologies and markets will have a major impact on the development of power electronics in the future. The paper discusses some of these implications, and outlines the technological and performance challenges for power electronic systems in alternative energy applications.

James P Lyons; Vlatko Vlatkovic

2004-01-01

346

NASA Astrophysics Data System (ADS)

The laser-induced dispersed vibration-rotation fluorescence method has been developed further when compared with a previous publication [Saarinen [et al.], J. Chem. Phys. 110, 1424 (1999)]. More than one order of magnitude better signal-to-noise ratio has been achieved in the wave-number region 2900-3500 cm-1 by taking advantage of directionality of the fluorescence signal. The improvement has been applied to overtone spectroscopy of normal acetylene where for high CH stretching excitations separate spectra of ortho and para forms are obtained containing basically just single CH stretching vibrational quantum transitions from the pumped antisymmetric vibrational (nu]1+3[nu]3([Sigmau)+ and nu]2+3[nu]3([Sigmau)+ and close-lying symmetric vibrational local mode (4nu]3([Sigmag)+ and nu]1+[nu]2+2[nu]3 (?g)+ states. No nuclear spin conversion is observed in these spectra. Two new symmetric vibrational states ?1+2?2+4?40 (?g)+)(29% and (50%)) have been observed and the precision of the spectroscopic parameters of previously published symmetric states has been improved by an order of magnitude. Unexpected fluorescence originating from the antisymmetric CH stretching fundamental state nu3 and some associated states of acetylene have also been observed. These spectra are characterized by both ortho and para forms in normal abundance and by unusual intensity patterns due to strong reabsorption of the fluorescence by ground state acetylene molecules in the sample cell. A simple collisional step-down mechanism is proposed to account for the appearance of the nu3 fluorescence band system. The excess vibrational energy in the sample volume is partly trapped in the form of nu3 mode energy and it decays from the system by radiation.

Metsala, Markus; Yang, Shengfu; Vaittinen, Olavi; Halonen, Lauri

2002-11-01

347

Non-classicality of the molecular vibrations assisting exciton energy transfer at room temperature

Advancing the debate on quantum effects in light-initiated reactions in biology requires clear identification of non-classical features that these processes can exhibit and utilize. Here we show that in prototype dimers present in a variety of photosynthetic antennae, efficient vibration-assisted energy transfer in the sub-picosecond timescale and at room temperature can manifest and benefit from non-classical fluctuations of collective pigment motions. Non-classicality of initially thermalized vibrations is induced via coherent exciton–vibration interactions and is unambiguously indicated by negativities in the phase–space quasi-probability distribution of the effective collective mode coupled to the electronic dynamics. These quantum effects can be prompted upon incoherent input of excitation. Our results therefore suggest that investigation of the non-classical properties of vibrational motions assisting excitation and charge transport, photoreception and chemical sensing processes could be a touchstone for revealing a role for non-trivial quantum phenomena in biology. PMID:24402469

O’Reilly, Edward J.; Olaya-Castro, Alexandra

2014-01-01

348

Laboratory Measurements of Room Temperature Vibrational Energy Transfer in O3 - O Collisions

NASA Astrophysics Data System (ADS)

Vibrational energy exchange between O3 and O may play a significant role in the temperature and density structure of Earth’s upper mesosphere / lower thermosphere between 60 and100km. More accurate laboratory measurements of this rate coefficient are needed to improve aeronomic models of the region. A slow flowing gas mixture of O3 in Ar/Xe bath gas through a 1m long cell is used to perform laboratory measurements of the rate coefficient for quenching of vibrationally excited O3 by O(3P). Nd:YAG pulses (266nm) are used to photodissociate a small fraction of the O3, providing O atoms and vibrationally excited O3 via a modest temperature jump (~10K). Diode laser absorption spectroscopy in the 1030cm-1 region is used to measure the time-evolving populations in various O3 vibrational states. Data are taken at varying O concentrations to allow determination of the rate coefficient of interest using a global nonlinear least squares regression fitting algorithm programmed in Visual FORTRAN. Recent progress and updated measurements will be reported.

Schaeffer, J.; Black, L.; Pedersen, T.; Castle, K. J.

2009-12-01

349

Vibrational Energy Relaxation of Choloroiodomethane in Cold Argon

NASA Astrophysics Data System (ADS)

Electronically exciting the C-I stretch in the molecule chloroiodomethane CH2ClI embedded in a matrix of argon at 20K can lead to an isomer, iso-chloroiodomethane CH2Cl-I, that features a chlorine iodine bond [T. J. Preston et al., J. Chem. Phys. {135}, 114503 (2011)]. By temporally probing the isomer at two different frequencies of 435 nm and 485 nm, three timescales for isomerization were inferred. The first and second timescales correspond to formation and initial relaxation of the isomer, with a decay rate of 0.45 ps-1. The third timescale is attributed to further energy loss as the molecule cools to its local minima, with a decay rate of 0.07 ps-1. To gain further mechanistic insights into this process, we studied the isomerization theoretically using molecular dynamics. Initial energy of 37,500 cm-1 (corresponding to electronic excitation of C-I stretch) is provided to the C-I bond. As in the experiment, three timescales are observed. First the molecule loses energy through collisions with a few argon atoms, which leads to a loss of about 10,000 cm-1 in 100 fs. Subsequent energy loss follows a bi-exponential decay, with decay rates of 1.16 ps-1 and 0.21 ps-1. The implications of our results to the interpretation of the spectroscopic results will be discussed.

Jain, A.; Sibert, E. L.

2012-06-01

350

Vibrational Energy Relaxation of Choloroiodomethane in Cold Argon

NASA Astrophysics Data System (ADS)

Electronically exciting the C-I stretch in the molecule chloroiodomethane CH_{2}ClI embedded in a matrix of argon at 12K can lead to an isomer, iso-chloroiodomethane CH_{2}Cl-I, that features a chlorine iodine bond. By temporally probing the isomer at two different frequencies of 435 nm and 485 nm, multiple timescales for isomerization are inferred. To gain further mechanistic insights into this process we have studied the isomerization theoretically using molecular dynamics. Two and three low frequency modes (C-Cl-I bend, Cl-I stretch and C-Cl stretch) are included in the model. The experiment is simulated by equilibrating the molecule in the parent configuration and providing an energy of 37,500 cm^{-1}, corresponding to the electronic excitation of the C-I stretch. Subsequent time evolution of the classical trajectories is monitored, and the decay rates of energy are compared to the experimental spectroscopy results. Varying different parameters related to the potential energy surface can lead to different results and their implications to the energy flow are discussed. The decay rates in the isomer well are also compared to the classical Landau Teller theory. T. J. Preston, M. Dutta, B. J. Esselman, A. Kalume, L. George, R. J. McMahon, S. A. Reid, and F. F. Crim, J. Chem. Phys. 135, 114503 (2011)

Jain, Amber; Sibert, Edwin L. Sibert, Iii

2013-06-01

351

Communication: Fast transport and relaxation of vibrational energy in polymer chains.

We investigate ballistic vibrational energy transport through optical phonon band in oligomeric chains in the presence of decoherence. An exact solution is obtained for the excitation density in the space-time representation in the continuous limit and this solution is used to characterize the energy transport time and intensity. Three transport mechanisms are identified such as ballistic, diffusive, and directed diffusive regimes, occurring at different distances and time scales. The crossover between the two diffusive regimes is continuous, while the switch between the ballistic and diffusive mechanisms occurs in a discontinuous manner in accord with the recent experimental results on energy transport in perfluoroalkanes. PMID:25573545

Kurnosov, Arkady A; Rubtsov, Igor V; Burin, Alexander L

2015-01-01

352

Study of vibrational energy transfer at a surface by a time-of-flight method

NASA Astrophysics Data System (ADS)

A single collision, time-of-flight extension of the VEM method for the study of molecule-surface vibrational energy transfer is introduced. This refined technique helps election between possible alternative trial analytic forms of the collisional transition probability function. A gaussian form is preferred over a boltzmann-exponential form for cyclobutene isomerization to 1,3-butadiene energized by collisions at a seasoned silica surface at 800 K. The study illustrates the difference between conventional accommodation coefficient measurements, which examine average energy changes, and the present studies which explore the energy transport at high levels corresponding to chemical reaction thresholds.

Yuan, W.; Rabinovitch, B. S.

1983-07-01

353

Communication: Fast transport and relaxation of vibrational energy in polymer chains

NASA Astrophysics Data System (ADS)

We investigate ballistic vibrational energy transport through optical phonon band in oligomeric chains in the presence of decoherence. An exact solution is obtained for the excitation density in the space-time representation in the continuous limit and this solution is used to characterize the energy transport time and intensity. Three transport mechanisms are identified such as ballistic, diffusive, and directed diffusive regimes, occurring at different distances and time scales. The crossover between the two diffusive regimes is continuous, while the switch between the ballistic and diffusive mechanisms occurs in a discontinuous manner in accord with the recent experimental results on energy transport in perfluoroalkanes.

Kurnosov, Arkady A.; Rubtsov, Igor V.; Burin, Alexander L.

2015-01-01

354

Platinum-hydrogen vibrations and low energy electronic excitations of 13-atom Pt nanoclusters.

Two Pt-H vibrational bands at 1679 cm(-1) and 1392 cm(-1) observed with 13-atom Pt clusters supported in LTL zeolite by Fourier Transform Infrared (FTIR) spectroscopy confirms that H atoms bridge two Pt atoms across the edges of the metal cluster. An additional broad absorption band centred near 2200 cm(-1) which exhibits some substructure is assigned to low energy electronic excitations across the HOMO-LUMO gap of the developing band structure of the nanocluster. PMID:25182177

Keppeler, Melanie; Roduner, Emil

2014-12-28

355

Interplay between vibrational energy transfer and excited state deactivation in DNA components.

Femtosecond laser spectroscopies are used to examine a thymine family of systems chosen to expose the interplay between excited state deactivation and two distinct vibrational energy transfer (VET) pathways: (i) VET from the base to the deoxyribose ring; (ii) VET between neighboring units in a dinucleotide. We find that relaxation in the ground electronic state accelerates markedly as the molecular sizes increase from the nucleobase to the dinucleotide. This behavior directly reflects growth in the density of vibrational quantum states on the substituent of the base. Excited state lifetimes are studied at temperatures ranging from 100 to 300 K to characterize the thermal fluctuations that connect the Franck-Condon geometries and the conical intersections leading back to the ground state. An Arrhenius analysis yields an approximate excited state energy barrier of 13 meV in the thymine dinucleotide. In addition, we find that the transfer of vibrational energy from the base to the substituent suppresses thermal fluctuations across this energy barrier. The possibility that the solvent viscosity imposes friction on the reaction coordinate is examined by comparing thymine and adenine systems. Experiments suggest that the solvent viscosity has little effect on barrier crossing dynamics in thymine because the conical intersection is accessed through relatively small out-of-plane atomic displacements. Overall, we conclude that the transfer of vibrational quanta from thymine to the deoxyribose ring couples significantly to the internal conversion rate, whereas the neighboring unit in the dinucleotide serves as a secondary heat bath. In natural DNA, it follows that (local) thermal fluctuations in the geometries of subunits involving the base and deoxyribose ring are most important to this subpicosecond relaxation process. PMID:22920964

West, Brantley A; Womick, Jordan M; Moran, Andrew M

2013-07-25

356

Laboratory Measurements of Room Temperature Vibrational Energy Transfer in O3 - O Collisions

Vibrational energy exchange between O3 and O may play a significant role in the temperature and density structure of Earth's upper mesosphere \\/ lower thermosphere between 60 and100km. More accurate laboratory measurements of this rate coefficient are needed to improve aeronomic models of the region. A slow flowing gas mixture of O3 in Ar\\/Xe bath gas through a 1m long

J. Schaeffer; L. Black; T. Pedersen; K. J. Castle

2009-01-01

357

Study of vibrational energy transfer at a surface by a time-of-flight method

A single collision, time-of-flight extension of the VEM method for the study of molecule-surface vibrational energy transfer is introduced. The technique helps election between possible alternative trial analytic forms of the collisional transition probability function. A Gaussian form is preferred over a Boltzmann-exponential form for cyclobutene isomerization to 1.3-butadiene energized by collisions at a silica surface at 800 K.

Yuan, W.; Rabinovitch, B.S.

1984-02-15

358

A quantum mechanical model of vibrational-electronic energy exchange during collisions

A model for the interchange of energy between an electronic and a vibrational mode during a collinear atom--molecule collision is proposed. Although crude, the model is simple enough to be solved exactly using the R-matrix propagator method for treating quantum close-coupling problems. These exact results can be compared to semiclassical and approximate treatments of the same problem. Several interesting features

T. G. Schmalz

1982-01-01

359

A quantum mechanical model of vibrational-electronic energy exchange during collisions

A model for the interchange of energy between an electronic and a vibrational mode during a collinear atom–molecule collision is proposed. Although crude, the model is simple enough to be solved exactly using the R-matrix propagator method for treating quantum close-coupling problems. These exact results can be compared to semiclassical and approximate treatments of the same problem. Several interesting features

T. G. Schmalz

1982-01-01

360

The reduction of rotorcraft power and vibration using optimally controlled active gurney flap

NASA Astrophysics Data System (ADS)

The main topic of the present study is the application of active control scheme for the reduction of rotorcraft main rotor power reduction and vibratory load. When the helicopter is operated near its flight boundary, the required power and vibratory loads rapidly increases which impose a limit on the helicopter operation. Various methods were proposed and studied in order to achieve performance improvement under such operating condition. The effect of active control scheme was examined for its impact on the performance improvement and vibration reduction in the present study. Numerical simulations are based on the UH-60A Blackhawk helicopter with an active Gurney flap spanning from 70%R to 80%R of the main rotor. For obtaining the aeroelastic response of the rotor blade, finite element method was used to represent elastic blade. The aerodynamic loads acting on the blade are provided by CFD based 2D lookup table. Prescribed wake model was used to resolve the induced inflow over the rotor disk. The unsteady aerodynamic behavior due to the higher harmonic actuation of active Gurney flap was resolved by the time-domain unsteady aerodynamic model. The first part of preliminary study covers parametric study using Gurney flap. Starting with simple rigid blade representation of the rotor blade, the effect of 1/rev Gurney flap actuation was examined on three different gross weights. The effect of active Gurney flap width, the chordwise location of active Gurney flap, the effect of unsteady aerodynamic model, and the effect of 2/rev actuation frequency were examined. The second part of preliminary study was conducted with the elastic blade model to include the effect of torsion dynamics. Performance improvement using active Gurney flap was examined for maximizing thrust capability at two flight speeds. 1/rev Gurney flap actuation increased the gross weight capability up to 1,000 lbs. Also, 1/rev actuation of Gurney flap increased maximum altitude limit of baseline rotor by 1,400 ft. Furthermore, it was predicted that the maximum level flight speed can be increased by 30 knots with respect to that of the baseline rotor. The effect of active Gurney flap on the vibration reduction was first examined at the stall condition. Using 1/rev actuation, in-plane vibratory force and moment can be reduced by 68% and 44%, respectively. The effects of higher harmonic frequencies were investigated at the high-speed cruise speed, and single frequency phase sweep was conducted to find the best phase angle that minimizes each vibratory components. 3/rev actuation yielded 36% reduction in in-plane vibratory moment. 74% reduction in vertical vibratory force was predicted with 4/rev actuation. With 5/rev actuation, 81% reduction in vertical vibratory load was observed. With the input-output information obtained from single frequency phase sweep, the plant model which correlates active control inputs to helicopter vibratory loads was constructed. Multicyclic controller was applied to the plant model, and 25% reduction in the cost function was reported. Vertical vibratory load was reduced by 51%, and inplane force and moment were reduced by 18%, 22%, respectively.

Bae, Eui Sung

361

NASA Astrophysics Data System (ADS)

The assessment of fatigue load under random vibrations is usually based on load spectra. Typically they are computed with counting methods (e.g. Rainflow) based on a time domain signal. Alternatively methods are available (e.g. Dirlik) enabling the estimation of load spectra directly from power spectral densities (PSDs) of the corresponding time signals; the knowledge of the time signal is then not necessary. These PSD based methods have the enormous advantage that if for example the signal to assess results from a finite element method based vibration analysis, the computation time of the simulation of PSDs in the frequency domain outmatches by far the simulation of time signals in the time domain. This is especially true for random vibrations with very long signals in the time domain. The disadvantage of the PSD based simulation of vibrations and also the PSD based load spectra estimation is their limitation to Gaussian distributed time signals. Deviations from this Gaussian distribution cause relevant deviations in the estimated load spectra. In these cases usually only computation time intensive time domain calculations produce accurate results. This paper presents a method dealing with non-Gaussian signals with real statistical properties that is still able to use the efficient PSD approach with its computation time advantages. Essentially it is based on a decomposition of the non-Gaussian signal in Gaussian distributed parts. The PSDs of these rearranged signals are then used to perform usual PSD analyses. In particular, detailed methods are described for the decomposition of time signals and the derivation of PSDs and cross power spectral densities (CPSDs) from multiple real measurements without using inaccurate standard procedures. Furthermore the basic intention is to design a general and integrated method that is not just able to analyse a certain single load case for a small time interval, but to generate representative PSD and CPSD spectra replacing extensive measured loads in time domain without losing the necessary accuracy for the fatigue load results. These long measurements may even represent the whole application range of the railway vehicle. The presented work demonstrates the application of this method to railway vehicle components subjected to random vibrations caused by the wheel rail contact. Extensive measurements of axle box accelerations have been used to verify the proposed procedure for this class of railway vehicle applications. The linearity is not a real limitation, because the structural vibrations caused by the random excitations are usually small for rail vehicle applications. The impact of nonlinearities is usually covered by separate nonlinear models and only needed for the deterministic part of the loads. Linear vibration systems subjected to Gaussian vibrations respond with vibrations having also a Gaussian distribution. A non-Gaussian distribution in the excitation signal produces also a non-Gaussian response with statistical properties different from these excitations. A drawback is the fact that there is no simple mathematical relation between excitation and response concerning these deviations from the Gaussian distribution (see e.g. Ito calculus [6], which is usually not part of commercial codes!). There are a couple of well-established procedures for the prediction of fatigue load spectra from PSDs designed for Gaussian loads (see [4]); the question of the impact of non-Gaussian distributions on the fatigue load prediction has been studied for decades (see e.g. [3,4,11-13]) and is still subject of the ongoing research; e.g. [13] proposed a procedure, capable of considering non-Gaussian broadbanded loads. It is based on the knowledge of the response PSD and some statistical data, defining the non-Gaussian character of the underlying time signal. As already described above, these statistical data are usually not available for a PSD vibration response that has been calculated in the frequency domain. Summarizing the above and considering the fact of having highly non-Gaussian exci

Wolfsteiner, Peter; Breuer, Werner

2013-10-01

362

Influence of temperature on thymine-to-solvent vibrational energy transfer.

At the instant following the non-radiative deactivation of its ??* electronic state, the vibrational modes of thymine possess a highly non-equilibrium distribution of excitation quanta (i.e., >4 eV in excess energy). Equilibrium is re-established through rapid (5 ps) vibrational energy transfer to the surrounding solvent. The mechanisms behind such vibrational cooling (VC) processes are examined here using femtosecond transient grating and two-dimensional photon echo spectroscopies conducted at 100 K and 300 K in a mixture of methanol and water. Remarkably, we find that this variation in temperature has essentially no impact on the VC kinetics. Together the experiments and a theoretical model suggest three possible mechanisms consistent with this behavior: (i) vibrational energy transfer from the solute to solvent initiates (directly) in intramolecular modes of the solute with frequencies >300 cm(-1); (ii) the relaxation induced increase in the temperature of the environment reduces the sensitivity of VC to the temperature of the equilibrium system; (iii) the time scale of solvent motion approaches 0.1 ps even at 100 K. Mechanism (i) deserves strong consideration because it is consistent with the conclusions drawn in earlier studies of isotope effects on VC in hydrogen bonding solvents. Our model calculations suggest that mechanism (ii) also plays a significant role under the present experimental conditions. Mechanism (iii) is ruled out on the basis of long-lived correlations evident in the photon echo line shapes at 100 K. These insights into photoinduced relaxation processes in thymine are made possible by our recent extension of interferometric transient grating and photon echo spectroscopies to the mid UV spectral region. PMID:21950869

West, Brantley A; Womick, Jordan M; Moran, Andrew M

2011-09-21

363

Influence of temperature on thymine-to-solvent vibrational energy transfer

NASA Astrophysics Data System (ADS)

At the instant following the non-radiative deactivation of its ??* electronic state, the vibrational modes of thymine possess a highly non-equilibrium distribution of excitation quanta (i.e., >4 eV in excess energy). Equilibrium is re-established through rapid (5 ps) vibrational energy transfer to the surrounding solvent. The mechanisms behind such vibrational cooling (VC) processes are examined here using femtosecond transient grating and two-dimensional photon echo spectroscopies conducted at 100 K and 300 K in a mixture of methanol and water. Remarkably, we find that this variation in temperature has essentially no impact on the VC kinetics. Together the experiments and a theoretical model suggest three possible mechanisms consistent with this behavior: (i) vibrational energy transfer from the solute to solvent initiates (directly) in intramolecular modes of the solute with frequencies >300 cm-1; (ii) the relaxation induced increase in the temperature of the environment reduces the sensitivity of VC to the temperature of the equilibrium system; (iii) the time scale of solvent motion approaches 0.1 ps even at 100 K. Mechanism (i) deserves strong consideration because it is consistent with the conclusions drawn in earlier studies of isotope effects on VC in hydrogen bonding solvents. Our model calculations suggest that mechanism (ii) also plays a significant role under the present experimental conditions. Mechanism (iii) is ruled out on the basis of long-lived correlations evident in the photon echo line shapes at 100 K. These insights into photoinduced relaxation processes in thymine are made possible by our recent extension of interferometric transient grating and photon echo spectroscopies to the mid UV spectral region.

West, Brantley A.; Womick, Jordan M.; Moran, Andrew M.

2011-09-01

364

NASA Astrophysics Data System (ADS)

For the purpose of 10G communication system upgrade for Guangdong Power Grid, laboratory simulation tests on dynamic and temperature cycle are performed for the reserved cables (stock optical cables) of existing 2.5G special optical cable lines that have operated for ten years, in order to verify the possibility of optical cable to be upgraded to a 10G transmission level and evaluate the degradation level of optical cables. This paper points out the necessity of laboratory test on attenuation performance in a wind-induced vibration environment, describes the test methods thereof, summarizes and analyzes a variety of optical attenuation performance data, and finds that the attenuation performance of current OPGW, ADSS, ADL optical fiber lines in wind-induced vibration environment meets the industry standards.

Li, Jie; Zhao, Ziyuan

2010-08-01

365

This paper reports on efficient interfacing of typical vibration-driven electromagnetic transducers for micro energy harvesting. For this reason, an adaptive charge pump for dynamic maximum power point tracking is compared with a novel active full-wave rectifier design. For efficient ultra-low voltage rectification, the introduced active diode design uses a common-gate stage in conjunction with supply-independent biasing. While this active rectifier

Dominic Maurath; Philipp F. Becker; Dirk Spreemann; Yiannos Manoli

2012-01-01

366

NASA Astrophysics Data System (ADS)

A semiclassical stochastic trajectory (SST) approach to the study of collision induced transitions in gas molecule-solid surface scattering is used to investigate vibrational-rotational-transiational-phonon energy transfer in the H 2, D 2, HD-(smooth)Pt systems. State-to-state rotationally and ro-vibrationally inelastic transition probabilities are determined using interaction potentials with varying strength of the long-range attractive component. Rigid and non-rigid surfaces are considered, the latter via the generalized Langevin-ghost atom technique. The results demonstrate that addition of a significant attractive interaction broadens the rotationally and ro-vibralionally inelastic probability distributions. This leads in the latter case to the replacement of the near-resonant vibration-rotation mechanism for vibrational relaxation by a much more effective and uniform vibration-rotation, translation mechanism.

Depristo, Andrew E.

1984-02-01

367

The hydrogen bond has been studied by chemists for nearly a century. Interest in this ubiquitous bond has led to several prototypical systems emerging to studying its behavior. Hydrogen chloride clusters stand as one such example. We present here a new many-body potential energy surface for (HCl)n constructed from one-, two-, and three-body interactions. The surface is constructed from previous highly accurate, semiempirical monomer and dimer surfaces, and a new high-level ab initio permutationally invariant full-dimensional three-body potential. The new three-body potential is based on fitting roughly 52,000 three-body energies computed using coupled cluster with single, doubles, perturbative triples, and explicit correlation and the augmented correlation consistent double-? basis set. The first application, described here, is to the ring HCl trimer, for which the many-body representation is exact. The new potential describes all known stationary points of the trimer as well its dissociation to either three monomers or a monomer and a dimer. The anharmonic vibrational energies are computed for the three H-Cl stretches, using explicit three-mode coupling calculations and local-monomer calculations with Hückel-type coupling. Both methods produce frequencies within 5 cm(-1) of experiment. A wavepacket calculation based on the Hückel model and full-dimensional classical calculation are performed to study the monomer H-Cl stretch vibration-vibration transfer process in the ring HCl trimer. Somewhat surprisingly, the results of the quantum and classical calculations are virtually identical, both exhibiting coherent beating of the excitation between the three monomers. Finally, this representation of the potential is used to study properties of larger clusters, namely to compute optimized geometries of the tetramer, pentamer, and hexamer and to perform explicit four-mode coupling calculations of the tetramer's anharmonic stretch frequencies. The optimized geometries are found to be in agreement with those of previous ab initio studies and the tetramer's anharmonic frequencies are computed within 11 cm(-1) of experiment. PMID:24444294

Mancini, John S; Bowman, Joel M

2014-09-01

368

In this paper, the authors propose a novel electric power supply system for implanted medical devices. The system is noninvasive and uses two kinds of energy, magnetic and ultrasonic. The system can provide high power levels harmlessly. The energies are obtained by two types of vibrator, i.e., piezo and magnetostriction devices. A prototype was built and it was verified experimentally that the system is basically able to provide power. At high frequencies, such as 100 kHz, the output power was higher than the conventional system using a transformer. The normalized output power per unit volume also exceeded the transformer system. PMID:14598116

Suzuki, Shin-nosuke; Katane, Tamotsu; Saito, Osami

2003-01-01

369

Teachers Environmental Resource Unit: Energy and Power.

ERIC Educational Resources Information Center

Problems associated with energy production and power are studied in this teacher's guide to better understand the impact of man's energy production on the environment, how he consumes energy, and in what quantities. The resource unit is intended to provide the teacher with basic information that will aid classroom review of these problems. Topics…

Bemiss, Clair W.

370

Anharmonic force field, vibrational energies, and barrier to inversion of SiH{sub 3}{sup -}

The full quartic force field of the ground electronic state of the silyl anion (SiH{sub 3}{sup -}) has been determined at the CCSD(T)-R12 level employing a [Si/H]=[16s11p6d5f/7s5p4d] basis set. The vibrational energy levels, using the quartic force field as a representation of the potential energy hypersurface around equilibrium, have been determined by vibrational perturbation theory carried out to second, fourth, and sixth order. The undetected vibrational fundamental for the umbrella mode, {nu}{sub 2}, is predicted to be 844 cm-1. High-quality ab initio quantum chemical methods, including higher-order coupled cluster (CC) and many-body perturbation (MP) theory with basis sets ranging from [Si/H] [5s4p2d/3s2p] to [8s7p6d5f4g3h/7s6p5d4f3g] have been employed to obtain the best possible value for the inversion barrier of the silyl anion. The rarely quantified effects of one- and two-particle relativistic terms, core correlation, and the diagonal Born-Oppenheimer correction (DBOC) have been included in the determination of the barrier for this model system. The final electronic (vibrationless) extrapolated barrier height of this study is 8351{+-}100 cm{sup -1}. (c) 2000 American Institute of Physics.

Aarset, Kirsten [Department of Theoretical Chemistry, Eoetvoes University, P.O. Box 32, H-1518 Budapest 112, (Hungary)] [Department of Theoretical Chemistry, Eoetvoes University, P.O. Box 32, H-1518 Budapest 112, (Hungary); Csaszar, Attila G. [Department of Theoretical Chemistry, Eoetvoes University, P.O. Box 32, H-1518 Budapest 112, (Hungary)] [Department of Theoretical Chemistry, Eoetvoes University, P.O. Box 32, H-1518 Budapest 112, (Hungary); Sibert, Edwin L. III [Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States)] [Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States); Allen, Wesley D. [Center for Computational Quantum Chemistry, University of Georgia, Athens, Georgia 30602 (United States)] [Center for Computational Quantum Chemistry, University of Georgia, Athens, Georgia 30602 (United States); Schaefer, Henry F. III [Center for Computational Quantum Chemistry, University of Georgia, Athens, Georgia 30602 (United States)] [Center for Computational Quantum Chemistry, University of Georgia, Athens, Georgia 30602 (United States); Klopper, Wim [Department of Chemistry, University of Oslo, P.O. Box 1033 Blindern, N-0315 Oslo, (Norway) [Department of Chemistry, University of Oslo, P.O. Box 1033 Blindern, N-0315 Oslo, (Norway); Theoretical Chemistry Group, Debye Institute, Utrecht University, Padualaan 14, NL-3584 CH Utrecht, The Netherlands (Netherlands); Noga, Jozef [Institute of Inorganic Chemistry, Slovak Academy of Sciences, SK-84236 Bratislava, (Slovakia)] [Institute of Inorganic Chemistry, Slovak Academy of Sciences, SK-84236 Bratislava, (Slovakia)

2000-03-01

371

In this paper, the authors propose a novel electric power supply system for implanted medical devices. The system is noninvasive\\u000a and uses two kinds of energy, magnetic and ultrasonic. The system can provide high power levels harmlessly. The energies are\\u000a obtained by two types of vibrator, i.e., piezo and magnetostriction devices. A prototype was built and it was verified experimentally

Shin-nosuke Suzuki; Tamotsu Katane; Osami Saito

2003-01-01

372

Semi-active controller design for vibration suppression and energy harvesting via LMI approach

NASA Astrophysics Data System (ADS)

The vibration control plays an important role in energy harvesting systems. Compared to the active control, semi-active control is a more preferred alternative for practical use. Many different semi-active control strategies have been developed, among which LQ-clip, Skyhook and model predictive control are the most popular strategies in literatures. In this paper, a different control strategy that designs semi-active controller via LMI approach is proposed. Different from clipping the control input after controller construction like most existing control methods, the proposed method fulfills the semi-active control input feasibility constraints before the controller construction. The methodology is developed through LMI approach which leads to a stabilizing linear controller to ensure semi-active constraint and the pre-designed performance. An illustrative example, vibration control system of a tall building, is presented to show the efficiency of the method and validate the new approach.

Liu, Yilun; Lin, Chi-Chang; Zuo, Lei

2014-04-01

373

A new deformed Schioberg-type potential and ro-vibrational energies for some diatomic molecules

We suggest a new deformed Schioberg-type potential for diatomic molecules. We show that it is equivalent to Tietz-Hua oscillator potential. We discuss how to relate our deformed Schioberg potential to Morse, to Deng-Fan, to the improved Manning-Rosen, and to the deformed modified Rosen-Morse potential models. We transform our potential into a proper form and use the supersymmetric quantization to find a closed form analytical solution for the ro-vibrational energy levels that are highly accurate over a wide range of vibrational and rotational quantum numbers. We discuss our results using 6-diatomic molecules H2, HF, N2, NO, O2, and O2. Our results turn out to compare excellently with those from a generalized pseudospectral numerical method.

Omar Mustafa

2014-09-24

374

Ab initio rotation-vibration energies of HOC + calculated using the nonrigid bender Hamiltonian

NASA Astrophysics Data System (ADS)

In a previous paper [W. P. Kraemer and P. R. Bunker, J. Mol. Spectrosc.101, 379-394 (1983)] the results of configuration interaction calculations, performed in order to investigate the bending potential of the molecular ion HOC +, were reported. In the present paper we give the results of such calculations including additional points on the potential surface chosen mainly in order to study the HO and OC stretching potentials at longer bond lengths. We have determined the rotation-vibration energies from this extended potential surface using a newly written computer program that diagonalizes the nonrigid bender Hamiltonian. We compare the results with those obtained using the second-order rotation-vibration perturbation Hamiltonian, the rigid bender Hamiltonian, and the semirigid bender Hamiltonian.

Beardsworth, R.; Bunker, P. R.; Jensen, Per; Kraemer, W. P.

1986-07-01

375

A test of an adiabatic treatment of rotation for vibration/rotation energies of polyatomic molecules

NASA Astrophysics Data System (ADS)

A test of a quantum adiabatic treatment of rotational energy for the calculation of vibrational/rotational energies and dynamics of polyatomic molecules is presented. The approach is given in detail for triatomic systems, where it is shown, in the symmetric-top limit, to be the quantum analog of an earlier semiclassical Hamiltonian of McCurdy and Miller. A test of the adiabatic and standard centrifugal sudden decoupling methods is made for all the bound states of HCO for total angular momentum of one. The adiabatic approach is shown to be significantly more accurate that the centrifugal sudden approximation.

Bowman, Joel M.

1994-01-01

376

Scavenging vibration energy from seismically isolated bridges using an electromagnetic harvester

NASA Astrophysics Data System (ADS)

The increasing worldwide efforts in securing renewable energy sources increase incentive for civil engineers to investigate whether the kinetic energy associated with the vibration of larger-scale structures can be harvested. Such a research remains challenging and incomplete despite that hundreds of related articles have been published in the last decade. Base isolation is one of the most popular means of protecting a civil engineering structure against earthquake forces. Seismic isolation hinges on the decoupling of the structure from the shaking ground, hence protecting the structure from stress and damage during an earthquake excitation. The low stiffness isolator inserted between the structure and the ground dominates the response leading to a structural system of longer vibration period. As a consequence of this period shift, the spectral acceleration is reduced, but higher response displacements are produced. To mitigate this side effect, usually isolators are combined with the use of additional energy dissipation. In this study, the feasibility of scavenging the need-to-be dissipated energy from the isolator installed in a seismically isolated bridge using an electromagnetic (EM) energy harvester is investigated. The EM energy harvester consists of an energy harvesting circuit and a capacitor for energy storage. A mathematical model for this proposed EM energy harvester is developed and implemented on an idealized base-isolated single-degree-of-freedom system. The effect of having this EM energy harvester on the performance of this seismic isolated system is analyzed and discussed. The potential of installing such an EM energy harvester on a seismically isolated bridge is also addressed.

Lu, Qiuchen; Loong, Chengning; Chang, Chih-Chen; Dimitrakopoulos, Elias G.

2014-04-01

377

Power Measurement Methods for Energy Efficient Applications

Energy consumption constraints on computing systems are more important than ever. Maintenance costs for high performance systems are limiting the applicability of processing devices with large dissipation power. New solutions are needed to increase both the computation capability and the power efficiency. Moreover, energy efficient applications should balance performance vs. consumption. Therefore power data of components are important. This work presents the most remarkable alternatives to measure the power consumption of different types of computing systems, describing the advantages and limitations of available power measurement systems. Finally, a methodology is proposed to select the right power consumption measurement system taking into account precision of the measure, scalability and controllability of the acquisition system. PMID:23778191

Calandrini, Guilherme; Gardel, Alfredo; Bravo, Ignacio; Revenga, Pedro; Lázaro, José L.; Toledo-Moreo, F. Javier

2013-01-01

378

Vibrational vs. translational energy in promoting a prototype metal–hydrocarbon insertion reaction

The reaction Y + CH4 ? HYCH3 ? YCH2 + H2 is initiated by C–H insertion involving a 20 ± 3 kcal/mol potential energy barrier. The reaction is studied in crossed molecular beams under two different conditions with nearly the same total energy. One experiment is carried out at a collision energy of 15.1 kcal/mol with one quantum of CH4 antisymmetric (?3) stretching vibrational excitation (8.63 kcal/mol), the other at a collision energy of 23.8 kcal/mol. The reaction cross-section for C–H stretch excited methane (?s) is found to be at least a factor of 2.2 times larger than for ground-state methane (?g) at the same total energy. PMID:18678904

Proctor, David L.; Davis, H. Floyd

2008-01-01

379

SPS Energy Conversion Power Management Workshop

NASA Technical Reports Server (NTRS)

Energy technology concerning photovoltaic conversion, solar thermal conversion systems, and electrical power distribution processing is discussed. The manufacturing processes involving solar cells and solar array production are summarized. Resource issues concerning gallium arsenides and silicon alternatives are reported. Collector structures for solar construction are described and estimates in their service life, failure rates, and capabilities are presented. Theories of advanced thermal power cycles are summarized. Power distribution system configurations and processing components are presented.

1980-01-01

380

Shock and vibration tests of uranium mononitride fuel pellets for a space power nuclear reactor

NASA Technical Reports Server (NTRS)

Shock and vibration tests were conducted on cylindrically shaped, depleted, uranium mononitride (UN) fuel pellets. The structural capabilities of the pellets were determined under exposure to shock and vibration loading which a nuclear reactor may encounter during launching into space. Various combinations of diametral and axial clearances between the pellets and their enclosing structures were tested. The results of these tests indicate that for present fabrication of UN pellets, a diametral clearance of 0.254 millimeter and an axial clearance of 0.025 millimeter are tolerable when subjected to launch-induced loads.

Adams, D. W.

1972-01-01

381

Low-power optical vibration detection by photoconductance monitoring with a laser speckle pattern.

We present a quantitative evaluation of the performance of a photoconductance-monitoring sensor array in a speckle-based vibration detection configuration. The device is found to be capable of detecting nanometer-amplitude vibrations in a single shot with incident intensities of only a few microwatts per square centimeter at kilohertz frequencies. This performance indicates that the photoconductance-monitoring array requires approximately 3 orders of magnitude lower intensity to achieve the same displacement sensitivity as competing technologies, such as photo-electromotive-force detectors. PMID:16315710

Heinz, Philip; Garmire, Elsa

2005-11-15

382

NASA Technical Reports Server (NTRS)

The Energy Finite Element Analysis (EFEA) is a finite element based computational method for high frequency vibration and acoustic analysis. The EFEA solves with finite elements governing differential equations for energy variables. These equations are developed from wave equations. Recently, an EFEA method for computing high frequency vibration of structures either in vacuum or in contact with a dense fluid has been presented. The presence of fluid loading has been considered through added mass and radiation damping. The EFEA developments were validated by comparing EFEA results to solutions obtained by very dense conventional finite element models and solutions from classical techniques such as statistical energy analysis (SEA) and the modal decomposition method for bodies of revolution. EFEA results have also been compared favorably with test data for the vibration and the radiated noise generated by a large scale submersible vehicle. The primary variable in EFEA is defined as the time averaged over a period and space averaged over a wavelength energy density. A joint matrix computed from the power transmission coefficients is utilized for coupling the energy density variables across any discontinuities, such as change of plate thickness, plate/stiffener junctions etc. When considering the high frequency vibration of a periodically stiffened plate or cylinder, the flexural wavelength is smaller than the interval length between two periodic stiffeners, therefore the stiffener stiffness can not be smeared by computing an equivalent rigidity for the plate or cylinder. The periodic stiffeners must be regarded as coupling components between periodic units. In this paper, Periodic Structure (PS) theory is utilized for computing the coupling joint matrix and for accounting for the periodicity characteristics.

Vlahopoulos, Nickolas

2005-01-01

383

Power Technologies Energy Data Book - Fourth Edition

This report, prepared by NREL's Strategic Energy Analysis Center, includes up-to-date information on power technologies, including complete technology profiles. The data book also contains charts on electricity restructuring, power technology forecasts, electricity supply, electricity capability, electricity generation, electricity demand, prices, economic indicators, environmental indicators, and conversion factors.

Aabakken, J.

2006-08-01

384

Energy Decisions: Is Solar Power the Solution?

ERIC Educational Resources Information Center

People around the world are concerned about affordable energy. It is needed to power the global economy. Petroleum-based transportation and coal-fired power plants are economic prime movers fueling the global economy, but coal and gasoline are also the leading sources of air pollution. Both of these sources produce greenhouse gases and toxins.…

Childress, Vincent W.

2011-01-01

385

Department of Energy Bonneville Power Administration

Program (Program) and to track performance indicators under the Federal Columbia River Power System (FCRPS-15-09 Management Question Performance Measure or Standard High Level Indicator Metrics Data Source CommentsDepartment of Energy Bonneville Power Administration P.O. Box 3621 Portland, Oregon 97208

386

NASA Astrophysics Data System (ADS)

The design optimization through modeling of a thinned bulk-PZT-based vibration energy harvester on a flexible polymeric substrate is presented. We also propose a simple foil-level fabrication process for their realization, by thinning the PZT down to 50 ?m and laminating it via dry film photoresist onto a PET substrate at low temperature (<85?°C). Two models, based on analytical and finite element modeling (FEM) methods, were developed and experimentally validated. The first, referred to as the hybrid model, is based mainly on analytical equations with the introduction of a correction factor derived from FEM simulations. The second, referred to as the numerical model, is fully based on COMSOL simulations. Both models have exhibited a very good agreement with the measured output power and resonance frequency. After their validation, a geometrical optimization through a parametric study was performed for the length, width, and thicknesses of the different layers comprising the device. As a result, an output power of 6.7 ?W at 49.8 Hz and 0.1 g, a normalized power density (NPD) of 11?683 ?W g-2 cm-3, and a figure of merit (FOM) of 227 ?W g-2 cm-3 were obtained for the optimized harvester.

Vásquez Quintero, Andrés; Besse, Nadine; Janphuang, Pattanaphong; Lockhart, Robert; Briand, Danick; de Rooij, Nico F.

2014-04-01

387

NASA Astrophysics Data System (ADS)

We propose a fine-grained stainless-steel as a promising material for a robust oscillator and investigate the dependence of frequency band width, resonance frequency, and output power on initial air gaps in electret-based vertical vibration energy harvesters. Beams of the oscillator showed a shallow side-etched depth less than 10 ?m, as well as smooth edges. The oscillator succeeded in travelling over 1-mm displacement without fracture. Also, we found that broader frequency band, as well as lower resonance frequency, can be achieved with reducing the initial air gap, whereas the output power exhibited a peak value at an optimal initial air gap. The results may be attributed to the soft spring effect induced by the stronger electrostatic force. Maximum output power density and FWHM of frequency band width of our harvester are 4.7 ?W/cm3 and 14 Hz at initial air gap 0.3 mm and acceleration 4.9 m/s2.

Asanuma, H.; Hara, M.; Oguchi, H.; Kuwano, H.

2014-11-01

388

Topology optimization and fabrication of low frequency vibration energy harvesting microdevices

NASA Astrophysics Data System (ADS)

Topological design of miniaturized resonating structures capable of harvesting electrical energy from low frequency environmental mechanical vibrations encounters a particular physical challenge, due to the conflicting design requirements: low resonating frequency and miniaturization. In this paper structural static stiffness to resist undesired lateral deformation is included into the objective function, to prevent the structure from degenerating and forcing the solution to be manufacturable. The rational approximation of material properties interpolation scheme is introduced to deal with the problems of local vibration and instability of the low density area induced by the design dependent body forces. Both density and level set based topology optimization (TO) methods are investigated in their parameterization, sensitivity analysis, and applicability for low frequency energy harvester TO problems. Continuum based variation formulations for sensitivity analysis and the material derivative based shape sensitivity analysis are presented for the density method and the level set method, respectively; and their similarities and differences are highlighted. An external damper is introduced to simulate the energy output of the resonator due to electrical damping and the Rayleigh proportional damping is used for mechanical damping. Optimization results for different scenarios are tested to illustrate the influences of dynamic and static loads. To demonstrate manufacturability, the designs are built to scale using a 3D microfabrication method and assembled into vibration energy harvester prototypes. The fabricated devices based on the optimal results from using different TO techniques are tested and compared with the simulation results. The structures obtained by the level set based TO method require less post-processing before fabrication and the structures obtained by the density based TO method have resonating frequency as low as 100 Hz. The electrical voltage response in the experiment matches the trend of the simulation data.

Deng, Jiadong; Rorschach, Katherine; Baker, Evan; Sun, Cheng; Chen, Wei

2015-02-01

389

NASA Astrophysics Data System (ADS)

Time-resolved IR emission spectroscopy has previously been used to characterize the 193 nm photodissociation dynamics of vinyl cyanide, H_{2}CC(H)CN. Of significance, it was observed that the major molecular elimination channels generated ro-vibrationally excited photofragments consisting of: HCN + H_{2}CC: and HNC + HCCH, for which the HCN / HNC branching ratio was deduced to be 3.3 to 1. In the present study, we examine the collisional deactivation of the vibrationally excited (E_{vib}=15 kcal mole^{-1} above the zero-point energy) ?_{1} NH and ?_{3} NC stretches of HNC, in response to collisions with a series of inert rare-gas atoms: Rg=He, Ar, Kr, and Xe. Spectral modeling of the IR emission allows direct determination of the time-dependent average internal energy of HNC, and therefore a quantification of the average energy lost per collision, as a function of the internal energy. Similar to vibrationally excited radicals, collisional deactivation of HNC is shown to be remarkably efficient, likely due to comparatively strong HNC / Rg intermolecular attractive interactions. Subsequently, depending upon the relative rates, excited HNC can either isomerize to the energetically more stable HCN, or be rapidly quenched and kinetically trapped as HNC. Potential implications for the astrophysical HNC / HCN abundance ratio problem will be discussed. M. J. Wilhelm, M. Nikow, L. Letendre, and H. L. Dai J. Chem. Phys. 130, 044307 (2009). M. J. Wilhelm, M. Nikow, J. M. Smith, and H. L. Dai J. Phys. Chem. Lett. 4, 23 (2013).

Wilhelm, Michael J.; Dai, Hai-Lung

2013-06-01

390

Coal and nuclear power: Illinois' energy future

This conference was sponsored by the Energy Resources Center, University of Illinois at Chicago; the US Department of Energy; the Illinois Energy Resources Commission; and the Illinois Department of Energy and Natural Resources. The theme for the conference, Coal and Nuclear Power: Illinois' Energy Future, was based on two major observations: (1) Illinois has the largest reserves of bituminous coal of any state and is surpassed in total reserves only by North Dakota, and Montana; and (2) Illinois has made a heavy commitment to the use of nuclear power as a source of electrical power generation. Currently, nuclear power represents 30% of the electrical energy produced in the State. The primary objective of the 1982 conference was to review these two energy sources in view of the current energy policy of the Reagan Administration, and to examine the impact these policies have on the Midwest energy scene. The conference dealt with issues unique to Illinois as well as those facing the entire nation. A separate abstract was prepared for each of the 30 individual presentations.

Not Available

1982-01-01

391

Space solar power - An energy alternative

NASA Technical Reports Server (NTRS)

The space solar power concept is concerned with the use of a Space Power Satellite (SPS) which orbits the earth at geostationary altitude. Two large symmetrical solar collectors convert solar energy directly to electricity using photovoltaic cells woven into blankets. The dc electricity is directed to microwave generators incorporated in a transmitting antenna located between the solar collectors. The antenna directs the microwave beam to a receiving antenna on earth where the microwave energy is efficiently converted back to dc electricity. The SPS design promises 30-year and beyond lifetimes. The SPS is relatively pollution free as it promises earth-equivalence of 80-85% efficient ground-based thermal power plant.

Johnson, R. W.

1978-01-01

392

Saving Energy Through Advanced Power Strips (Poster)

Advanced Power Strips (APS) look just like ordinary power strips, except that they have built-in features that are designed to reduce the amount of energy used by many consumer electronics. There are several different types of APSs on the market, but they all operate on the same basic principle of shutting off the supply power to devices that are not in use. By replacing your standard power strip with an APS, you can signifcantly cut the amount of electricity used by your home office and entertainment center devices, and save money on your electric bill. This illustration summarizes the different options.

Christensen, D.

2013-10-01

393

Optimal Power Allocation for Renewable Energy Source

Battery powered transmitters face energy constraint, replenishing their energy by a renewable energy source (like solar or wind power) can lead to longer lifetime. We consider here the problem of finding the optimal power allocation under random channel conditions for a wireless transmitter, such that rate of information transfer is maximized. Here a rechargeable battery, which is periodically charged by renewable source, is used to power the transmitter. All of above is formulated as a Markov Decision Process. Structural properties like the monotonicity of the optimal value and policy derived in this paper will be of vital importance in understanding the kind of algorithms and approximations needed in real-life scenarios. The effect of curse of dimensionality which is prevalent in Dynamic programming problems can thus be reduced. We show our results under the most general of assumptions.

Sinha, Abhinav

2011-01-01

394

Instantaneous pair theory for high-frequency vibrational energy relaxation in fluids

NASA Astrophysics Data System (ADS)

Notwithstanding the long and distinguished history of studies of vibrational energy relaxation, exactly how it is that high frequency vibrations manage to relax in a liquid remains somewhat of a mystery. Both experimental and theoretical approaches seem to say that there is a natural frequency range associated with intermolecular motion in liquids, typically spanning no more than a few hundred cm-1. Landau-Teller-type theories explain rather easily how a solvent can absorb any vibrational energy within this "band," but how is it that molecules can rid themselves of superfluous vibrational energies significantly in excess of these values? In this paper we develop a theory for such processes based on the idea that the crucial liquid motions are those that most rapidly modulate the force on the vibrating coordinate — and that by far the most important of these motions are those involving what we have called the mutual nearest neighbors of the vibrating solute. Specifically, we suggest that whenever there is a single solvent molecule sufficiently close to the solute that the solvent and solute are each other's nearest neighbors, then the instantaneous scattering dynamics of the solute-solvent pair alone suffices to explain the high-frequency relaxation. This highly reduced version of the dynamics has implications for some of the previous theoretical formulations of this problem. Previous instantaneous-normal-mode theories allowed us to understand the origin of a band of liquid frequencies, and even had some success in predicting relaxation within this band, but lacking a sensible picture of the effects of liquid anharmonicity on dynamics, were completely unable to treat higher frequency relaxation. When instantaneous-normal-mode dynamics is used to evaluate the instantaneous pair theory, though, we end up with a multiphonon picture of the relaxation which is in excellent agreement with the exact high-frequency dynamics — suggesting that the critical anharmonicity behind the relaxation is not in the complex, underlying liquid dynamics, but in the relatively easy-to-understand nonlinear solute-solvent coupling. There are implications, as well, for the independent binary collision (IBC) theory of vibrational relaxation in liquids. The success of the instantaneous-pair approach certainly provides a measure of justification for the IBC model's focus on few-body dynamics. However, the pair theory neither needs nor supports the basic IBC factoring of relaxation rates into many-body and few-body dynamical components — into collision rates and relaxation rates per collision. Rather, our results favor taking an instantaneous perspective: the relaxation rate is indeed exercise in few-body dynamics, but a different exercise for each instantaneous liquid configuration. The many-body features therefore appear only in the guise of a purely equilibrium problem, that of finding the likelihood of particularly effective solvent arrangements around the solute. All of these results are tested numerically on model diatomic solutes dissolved in atomic fluids (including the experimentally and theoretically interesting case of I2 dissolved in Xe). The instantaneous pair theory leads to results in quantitative agreement with those obtained from far more laborious exact molecular dynamics simulations.

Larsen, Ross E.; Stratt, Richard M.

1999-01-01

395

Fluid Power Systems. Energy Technology Series.

ERIC Educational Resources Information Center

This course in fluid power systems is one of 16 courses in the Energy Technology Series developed for an Energy Conservation-and-Use Technology curriculum. Intended for use in two-year postsecondary technical institutions to prepare technicians for employment, the courses are also useful in industry for updating employees in company-sponsored…

Center for Occupational Research and Development, Inc., Waco, TX.

396

Breezy Power: From Wind to Energy

ERIC Educational Resources Information Center

This lesson combines the science concepts of renewable energy and producing electricity with the technology concepts of design, constraints, and technology's impact on the environment. Over five class periods, sixth-grade students "work" for a fictitious power company as they research wind as an alternative energy source and design and test a…

Claymier, Bob

2009-01-01

397

Stopping Power from SPS to LHC energies

We investigate the energy dependence of hadron production and of stopping power based on HIJING/BBbar v2.0 model calculations. Pseudorapidity spectra and transverse momentum distributions for produced charged particles as well as net baryons (per pair of partcipants) and their rapidity loss are compared to data at RHIC and predictions for LHC energies are discussed.

V. Topor Pop; J. Barrette; C. Gale; S. Jeon; M. Gyulassy

2007-05-18

398

Wind energy for remote telecommunications power

Technological developments of small wind energy conversion systems have accelerated in the past decade. These systems are being evaluated for their technical feasibility, competitive costs of electric power generation, high reliability of design and performance, and minimal environmental impact. Small wind energy conversion systems are commercially available and, for select applications, are cost competitive. They have been used to provide

Thorn

1981-01-01

399

We introduce a new reduced-coupling technique to accelerate direct calculations of a selected number of vibrational frequencies in large molecular systems. Our method combines the advantages of the single-to-all correlation-corrected vibrational self-consistent field (STA-CC-VSCF) approach [D. M. Benoit, J. Chem. Phys. 125, 244110 (2006)] with those of the fast-CC-VSCF technique [D. M. Benoit, J. Chem. Phys. 120, 562 (2004)] and allows the ab initio calculation of only the relevant parts of the required potential energy surface (PES). We demonstrate, using a set of five aliphatic alcohol molecules, that the new fast-STA-CC-VSCF method is accurate and leads to very substantial time gains for the computations of the PES. We then use the fast-STA-CC-VSCF method to accelerate the computation of the OH-stretch and NH-stretch frequencies of the two lowest-energy conformers of noradrenaline, namely, AG1a and GG1a. Our new approach enables us to run the calculation 89 times faster than the standard CC-VSCF technique and makes it possible to use a high-level MP2/TZP description of the PES. We demonstrate that the influence of the strong mode-mode couplings is crucial for a realistic description of the particular OH-stretch vibrational signature of each conformer. Finally, of the two possible low-energy conformers, we identify AG1a as the one most likely to have been observed in the experiments of Snoek et al. [Mol. Phys. 101, 1239 (2003)]. PMID:19102529

Benoit, David M

2008-12-21

400

NASA Astrophysics Data System (ADS)

Scavenging electromagnetic and vibration energy from environments is an attractive technique for powering wireless sensors in a wireless sensor network. This paper reports our design and testing results on the electric output performance of a piezoelectric energy harvesting device, which consists of cantilever beams, magnetoelectric (ME) transducers, and permanent magnets. The geometric parameters of the device are based on an optimization design with a targeted resonant frequency of 50 Hz. Experimental results show that an output voltage of 56.1 V and an average power of 0.24 mW are achieved responding to a current of 3 A at 50 Hz. Remarkably, this power is a very encouraging power figure that gives the prospect of being able to power a wide range of wireless sensors in an electric line monitoring system.

Qiu, Jing; Wen, Yumei; Li, Ping; Yang, Jin

2012-04-01

401

In this work we present a full 6D quartic potential energy surface (PES) for S0 thiophosgene in curvilinear symmetrized bond-angle coordinates. The PES was refined starting from an ab initio field derived from acc-pVTZ basis set with CCSD(T) corrections for electron correlation. In the present calculations we used our variational method that was recently tested on formaldehyde and some of its isotopomers, along with additional improvements. The lower experimentally known vibrational levels for (35)Cl2CS were reproduced quite well in the calculations, which can be regarded as a test for the feasibility of the obtained quartic PES. PMID:25615683

Rashev, Svetoslav; Moule, David C

2015-04-01

402

NASA Technical Reports Server (NTRS)

The vibrational frequencies of MO2 are computed at many levels of theory, including HF, B3LYP, BP86, CASSCF, MP2, and CCSD(T). The computed results are compared with the available experimental results. Most of the methods fail for at least one state of the systems considered. The accuracy of the results and the origin of the observed failures are discussed. The B3LYP bond energies are compared with traditional methods for a variety of systems, ranging from FeCOn+ to SiCln and its positive ions. The cases where B3LYP differs from the traditional methods are discussed.

Bauschlicher, Charles W.; Arnold, James O. (Technical Monitor)

1997-01-01

403

We study the intramolecular vibrational energy redistribution (IVR) dynamics of an effective spectroscopic Hamiltonian describing the four coupled high frequency modes of CDBrClF. The IVR dynamics ensuing from nearly isoenergetic zeroth-order states, an edge (overtone) and an interior (combination) state, is studied from a state space diffusion perspective. A wavelet based time-frequency analysis reveals an inhomogeneous phase space due to the trapping of classical trajectories. Consequently the interior state has a smaller effective IVR dimension as compared to the edge state.

Aravindan Semparithi; Srihari Keshavamurthy

2007-01-30

404

Vibrational energy transfer in OH A 2?+ between 195 and 295 K

NASA Astrophysics Data System (ADS)

Vibrational energy transfer (VET) v'=1?0 and electronic quenching of v'=1 and 0 in the A 2?+ electronically excited state of the OH radical has been studied over the temperature range 195 to 295 K. The colliders investigated were N2, O2, and CO2. Laser-induced fluorescence experiments were conducted in a flow cell with photolytic production of OH; both fluorescence intensity and time decay measurements were made. The VET cross sections are found to increase with decreasing temperature, suggestive of attractive force interactions in the VET process.

Steffens, Kristen L.; Crosley, David R.

2000-06-01

405

Energy Servers Deliver Clean, Affordable Power

NASA Technical Reports Server (NTRS)

K.R. Sridhar developed a fuel cell device for Ames Research Center, that could use solar power to split water into oxygen for breathing and hydrogen for fuel on Mars. Sridhar saw the potential of the technology, when reversed, to create clean energy on Earth. He founded Bloom Energy, of Sunnyvale, California, to advance the technology. Today, the Bloom Energy Server is providing cost-effective, environmentally friendly energy to a host of companies such as eBay, Google, and The Coca-Cola Company. Bloom's NASA-derived Energy Servers generate energy that is about 67-percent cleaner than a typical coal-fired power plant when using fossil fuels and 100-percent cleaner with renewable fuels.

2010-01-01

406

Collisional energy transfer between vibrational ground state CO2 and highly vibrationally excited monofluorobenzene (MFB) was studied using narrow bandwidth (0.0003 cm(-1)) IR diode laser absorption spectroscopy. Highly vibrationally excited MFB with E' = ?41?000 cm(-1) was prepared by 248 nm UV excitation followed by rapid radiationless internal conversion to the electronic ground state (S1?S0*). The amount of vibrational energy transferred from hot MFB into rotations and translations of CO2 via collisions was measured by probing the scattered CO2 using the IR diode laser. The absolute state specific energy transfer rate constants and scattering probabilities for single collisions between hot MFB and CO2 were measured and used to determine the energy transfer probability distribution function, P(E,E'), in the large ?E region. P(E,E') was then fit to a bi-exponential function and extrapolated to the low ?E region. P(E,E') and the biexponential fit data were used to determine the partitioning between weak and strong collisions as well as investigate molecular properties responsible for large collisional energy transfer events. Fermi's Golden rule was used to model the shape of P(E,E') and identify which donor vibrational motions are primarily responsible for energy transfer. In general, the results suggest that low-frequency MFB vibrational modes are primarily responsible for strong collisions, and govern the shape and magnitude of P(E,E'). Where deviations from this general trend occur, vibrational modes with large negative anharmonicity constants are more efficient energy gateways than modes with similar frequency, while vibrational modes with large positive anharmonicity constants are less efficient at energy transfer than modes of similar frequency. PMID:25527934

Kim, Kilyoung; Johnson, Alan M; Powell, Amber L; Mitchell, Deborah G; Sevy, Eric T

2014-12-21

407

NASA Astrophysics Data System (ADS)

Collisional energy transfer between vibrational ground state CO2 and highly vibrationally excited monofluorobenzene (MFB) was studied using narrow bandwidth (0.0003 cm-1) IR diode laser absorption spectroscopy. Highly vibrationally excited MFB with E' = ˜41 000 cm-1 was prepared by 248 nm UV excitation followed by rapid radiationless internal conversion to the electronic ground state (S1?S0*). The amount of vibrational energy transferred from hot MFB into rotations and translations of CO2 via collisions was measured by probing the scattered CO2 using the IR diode laser. The absolute state specific energy transfer rate constants and scattering probabilities for single collisions between hot MFB and CO2 were measured and used to determine the energy transfer probability distribution function, P(E,E'), in the large ?E region. P(E,E') was then fit to a bi-exponential function and extrapolated to the low ?E region. P(E,E') and the biexponential fit data were used to determine the partitioning between weak and strong collisions as well as investigate molecular properties responsible for large collisional energy transfer events. Fermi's Golden rule was used to model the shape of P(E,E') and identify which donor vibrational motions are primarily responsible for energy transfer. In general, the results suggest that low-frequency MFB vibrational modes are primarily responsible for strong collisions, and govern the shape and magnitude of P(E,E'). Where deviations from this general trend occur, vibrational modes with large negative anharmonicity constants are more efficient energy gateways than modes with similar frequency, while vibrational modes with large positive anharmonicity constants are less efficient at energy transfer than modes of similar frequency.

Kim, Kilyoung; Johnson, Alan M.; Powell, Amber L.; Mitchell, Deborah G.; Sevy, Eric T.

2014-12-01

408

The authors report variational calculations of vibrational energies of CH{sub 4}, CH{sub 3}D, CH{sub 2}D{sub 2}, CHD{sub 3}, and CD{sub 4} using the code Multimode and the ab initio force field of Lee and co-workers [Lee, T.J.; Martin, J.M.L.; Taylor, P.R.--J.Chem.Phys. 1995, 102, 254], re-expressed using Morse variables in the stretch displacements. Comparisons are made with experimental energies for CH{sub 4} with this potential, and then small adjustments are made to the potential to improve agreement with experiment for CH{sub 4}. Calculations for the isotopomers are done using the adjusted potential and compared with experiment. Additional vibrational energies and assignments not reported experimentally are also given for CH{sub 4} and the isotopomers. Exact rotational-vibrational energies of CH{sub 4} are also reported for J = 1.

Carter, S.; Bowman, J.M.

2000-03-23

409

The influence of translational and vibrational energy on the reaction of Cl with CH{sub 3}D

The reaction of Cl atoms with CH{sub 3}D proceeds either by abstraction of hydrogen to produce HCl + CH{sub 2}D or by abstraction of deuterium to produce DCl + CH{sub 3}. Using Cl atoms with different amounts of translational energy, produced by photolysis of Cl{sub 2} with 309, 355, or 416 nm light, reveals the influence of translational energy on the relative reaction probability for the two channels. These measurements give an estimate of the energy barrier for the reaction for comparison to theory and indicate that tunneling is the dominant reaction mechanism at low collision energies. Adding two quanta of C-H stretching vibration causes the reaction to proceed readily at all collision energies. Detecting the vibrational state of the CH{sub 2}D product shows that vibrational energy initially in the surviving C-H bond appears as vibrational excitation of the product, an example of spectator behavior in the reaction. The reaction produces both stretch and stretch-bend excited products except at the lowest collision energy. A subtle variation in the reaction probability of the lowest energy rotational states with translational energy may reflect the presence of a van der Waals well in the entrance channel.

Berke, Andrew E.; Volpa, Ethan H.; Annesley, Christopher J.; Crim, F. Fleming [Department of Chemistry, University of Wisconsin - Madison, Madison, Wisconsin 53706 (United States)

2013-06-14

410

NASA Astrophysics Data System (ADS)

We report electron-energy-loss spectroscopy, within the incident electron energy range 1 to 19 eV, of solid films of acetone condensed at 18 K. The strong Rydberg progressions, which usually dominate the spectra in the gas phase, are found to completely disappear in the solid phase. In the absence of these transitions, the remaining broad bands centered at 4.3, 4.5, 6.2, 8.7, and 9.8 eV energy loss can be assigned to the 1 3A2(n??*), 1 1A2(n??*), 1 3A1(???*), 1 3B1(???*), and 2 3A2(???*) valence electronic transition of acetone, respectively. A broad feature ranging from 11 to 16 eV and having a maximum around 13.8 eV is ascribed to several overlapping autoionizing excited states. From a comparison with infrared and Raman spectra, the energy-loss peaks observed below 1 eV are found to be due to excitation of the fundamental, overtone, and combination vibrational modes of the molecule. Their incident energy dependence is showing broad vibrational enhancement maxima at 4, 7, and 9 eV, which are attributed to the formation of single-particle or shape resonances of 2B1, 2A1, and 2A2 (or 2B2) symmetries, respectively.

Lepage, M.; Michaud, M.; Sanche, L.

2000-04-01

411

NASA Technical Reports Server (NTRS)

A description is given of an algorithm for computing ro-vibrational energy levels for tetratomic molecules. The expressions required for evaluating transition intensities are also given. The variational principle is used to determine the energy levels and the kinetic energy operator is simple and evaluated exactly. The computational procedure is split up into the determination of one dimensional radial basis functions, the computation of a contracted rotational-bending basis, followed by a final variational step coupling all degrees of freedom. An angular basis is proposed whereby the rotational-bending contraction takes place in three steps. Angular matrix elements of the potential are evaluated by expansion in terms of a suitable basis and the angular integrals are given in a factorized form which simplifies their evaluation. The basis functions in the final variational step have the full permutation symmetries of the identical particles. Sample results are given for HCCH and BH3.

Schwenke, David W.; Langhoff, Stephen R. (Technical Monitor)

1995-01-01

412

NASA Astrophysics Data System (ADS)

The variable encounter method has been used to study vibrational energy transients in the isomerization of methylcyclopropane to various butenes. This system was studied with reactor surface temperatures of 800 to 1130 K and average numbers of collisions per encounter with the reactor of 5.6 and 20.0. The reaction rate was treated on the basis of total, rather than individual butene rates, because of butene product interconversion. An exponential model of energy transfer was found to fit to the data with the average down step energy decreasing from 1860 to 1415 cm-1 with increase of temperature over the range studied. Incubation times increased from 14 to 19 collisions with increase in temperature, and these times, together with values of the conventional relative collision efficiency ? and values of , are compared with those of other molecules studied by VEM. The calculated transient population distributions and the associated sequential reaction probabilities are also displayed.

Kelley, D. F.; Kasai, T.; Rabinovitch, B. S.

1980-12-01

413

'People Power' Saves Plant Energy

and air cooler fans, turning off tracing steam, keeping turbine hand valves closed where possible, and continued emphasis on all phases of proper fired-heater operation. Po tential subjects for Energy-Grams are many. They should be eye... In parallel when only one is required. A 300 hp turbine drive spare pump was being run in parallel with a motor driven pump. Investigation showed that the spare pump only needed to be run during the summer months. Savings resulted from shutting down...

Davidson, B. G., Jr.; Kanewske, F. J.

1981-01-01

414

The structural stability and internal rotations in cyclopropanecarboxylic acid and cyclopropanecarboxamide were investigated by the DFT-B3LYP and the ab initio MP2 calculations using 6-311G** and 6-311+G** basis sets. The computations were extended to the MP4//MP2/6-311G** and CCSD(T)//MP2/6-311G** single-point calculations. From the calculations the molecules were predicted to exist predominantly in the cis (C=O group eclipses the cyclopropane ring) with a cis-trans barrier of about 4-6kcal/mol. The OCOH torsional barrier in the acid was estimated to be about 12-13kcal/mol while the corresponding OCNH torsional barrier in the amide was calculated to be about 20kcal/mol. The equilibrium constant k for the cis<-->trans interconversion in cyclopropanecarboxylic acid was calculated to be 0.1729 at 298.15K that corresponds to an equilibrium mixture of about 85% cis and 15% trans. The vibrational frequencies were computed at the DFT-B3LYP level. Normal coordinate calculations were carried out and potential energy distributions were calculated for the low energy cis conformer of the molecules. Complete vibrational assignments were made on the basis of normal coordinate calculations and comparison with experimental data of the molecules. PMID:18599341

Badawi, H M; Al-Saadi, A A; Al-Khaldi, M A A; Al-Abbad, S A; Al-Sunaidi, Z H A

2008-12-15

415

of the trajectories illustrates how mode-specific vibrational excitation effects the efficiency of translational-to-vibrational and xenon.14 Our experiments directly probed the effects of Ecol and five dif- ferent H2CO vibrational modes transfer dynamics, and the effects of impact parameter and reactant vibrational excitation on CID. One

Anderson, Scott L.

416

NASA Astrophysics Data System (ADS)

A three-dimensional, nonperturbative, semiclassical analytic model of vibrational energy transfer in collisions between a rotating diatomic molecule and an atom, and between two rotating diatomic molecules (Forced Harmonic Oscillator-Free Rotation model) has been extended to incorporate rotational relaxation and coupling between vibrational, translational, and rotational energy transfer. The model is based on analysis of semiclassical trajectories of rotating molecules interacting by a repulsive exponential atom-to-atom potential. The model predictions are compared with the results of three-dimensional close-coupled semiclassical trajectory calculations using the same potential energy surface. The comparison demonstrates good agreement between analytic and numerical probabilities of rotational and vibrational energy transfer processes, over a wide range of total collision energies, rotational energies, and impact parameter. The model predicts probabilities of single-quantum and multi-quantum vibrational-rotational transitions and is applicable up to very high collision energies and quantum numbers. Closed-form analytic expressions for these transition probabilities lend themselves to straightforward incorporation into DSMC nonequilibrium flow codes.

Adamovich, Igor V.

2014-04-01

417

A three-dimensional, nonperturbative, semiclassical analytic model of vibrational energy transfer in collisions between a rotating diatomic molecule and an atom, and between two rotating diatomic molecules (Forced Harmonic Oscillator–Free Rotation model) has been extended to incorporate rotational relaxation and coupling between vibrational, translational, and rotational energy transfer. The model is based on analysis of semiclassical trajectories of rotating molecules interacting by a repulsive exponential atom-to-atom potential. The model predictions are compared with the results of three-dimensional close-coupled semiclassical trajectory calculations using the same potential energy surface. The comparison demonstrates good agreement between analytic and numerical probabilities of rotational and vibrational energy transfer processes, over a wide range of total collision energies, rotational energies, and impact parameter. The model predicts probabilities of single-quantum and multi-quantum vibrational-rotational transitions and is applicable up to very high collision energies and quantum numbers. Closed-form analytic expressions for these transition probabilities lend themselves to straightforward incorporation into DSMC nonequilibrium flow codes.

Adamovich, Igor V. [Nonequilibrium Thermodynamics Laboratory, Department of Mechanical and Aerospace Engineering, The Ohio State University, Columbus, Ohio 43210 (United States)] [Nonequilibrium Thermodynamics Laboratory, Department of Mechanical and Aerospace Engineering, The Ohio State University, Columbus, Ohio 43210 (United States)

2014-04-15

418

Power Generation Characteristics of Single Electrode Output Circuit in Electret Energy Harvester

NASA Astrophysics Data System (ADS)

This paper reports the new output circuit using a single electrode in electret energy harvester, and proves that the single electrode is able to generate output power on grounded load. 3D numerical model of gap-closing type electret energy harvester is presented, and power generation characteristics are analysed and verified. Results show that the two electrodes are actually two independent current sources. Single electrode output circuit has two merits: when only one electrode is connected, it reduces wiring difficulty; when both electrodes are connected to grounded load respectively, it doubles output power compared with traditional output circuit. Using proposed circuit, maximal total power of 30mm×20mm prototype reaches 154.5?W@10Hz, 1.8mm sinusoidal vibration, and an LED has been successfully lighted up.

Bu, L.; Xu, H. Y.; Xu, B. J.; Song, L.

2014-11-01

419

Far-infrared vibration-rotation-tunneling spectroscopy of Ar-NH3: Intermolecular vibrations intermolecular vibration-rotation-tunneling (VRT) bandsof Ar-NH3 havebeen measuredusingtunable far infrared'employeda close-couplingmethod to fit exten- sive far-infrared vibration rotation tunneling (FIR-VRT) spectraof

Cohen, Ronald C.

420

NASA Astrophysics Data System (ADS)

In this paper, we discern two basic mechanisms of internal conversion processes; one direct, where immediate activation of coupling modes leads to fast population transfer and one indirect, where internal vibrational energy redistribution leads to equidistribution of energy, i.e., ergodicity, and slower population transfer follows. Using model vibronic coupling Hamiltonians parameterized on the basis of coupled-cluster calculations, we investigate the nature of the Rydberg to valence excited-state internal conversion in two cycloketones, cyclobutanone and cyclopentanone. The two basic mechanisms can amply explain the significantly different time scales for this process in the two molecules, a difference which has also been reported in recent experimental findings [T. S. Kuhlman, T. I. Sølling, and K. B. Møller, ChemPhysChem. 13, 820 (2012)], 10.1002/cphc.201100929.

Kuhlman, Thomas S.; Sauer, Stephan P. A.; Sølling, Theis I.; Møller, Klaus B.

2012-12-01