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1

Power-amplifying strategy in vibration-powered energy harvesters  

Microsoft Academic Search

A new cantilevered piezoelectric energy harvester (PEH) of which the additional lumped mass is connected to a harmonically oscillating base through an elastic foundation is proposed for maximizing generated power and enlarging its frequency bandwidth. The base motion is assumed to provide a given acceleration level. Earlier, a similar energy harvester employing the concept of the dynamic vibration absorber was

Pyung Sik Ma; Jae Eun Kim; Yoon Young Kim

2010-01-01

2

Power-amplifying strategy in vibration-powered energy harvesters  

NASA Astrophysics Data System (ADS)

A new cantilevered piezoelectric energy harvester (PEH) of which the additional lumped mass is connected to a harmonically oscillating base through an elastic foundation is proposed for maximizing generated power and enlarging its frequency bandwidth. The base motion is assumed to provide a given acceleration level. Earlier, a similar energy harvester employing the concept of the dynamic vibration absorber was developed but the mechanism of the present energy harvester is new because it incorporates a mass-spring system in addition to a conventional cantilevered piezoelectric energy harvesting beam with or without a tip mass. Consequently, the proposed energy harvester actually forms a two-degree-of-freedom system. It will be theoretically shown that the output power can be indeed substantially improved if the fundamental resonant frequencies of each of the two systems in the proposed energy harvester are simultaneously tuned as closely as possible to the input excitation frequency and also if the mass ratio of a piezoelectric energy harvesting beam to the lumped mass is adjusted below a certain value. The performance of the proposed energy harvester is checked by numerical simulation.

Ma, Pyung Sik; Kim, Jae Eun; Kim, Yoon Young

2010-03-01

3

An energy-adaptive MPPT power management unit for micro-power vibration energy harvesting  

Microsoft Academic Search

A batteryless power management unit (PMU) that manages harvested low-level vibration energy from a piezoelectric device for a wireless sensor node is presented. An energy-adaptive maximum power point tracking (EA-MPPT) scheme is proposed that allows the PMU to activate different operation modes according to the available power level. The harvested energy is processed by an ac-dc voltage doubler followed by

Jun Yi; Feng Su; Yat-hei Lam; Wing-hung Ki; Chi-ying Tsui

2008-01-01

4

Electromagnetic Vibration Power Generator  

Microsoft Academic Search

This paper shows an alternative for supplying wireless sensors with energy: electrical power is generated from an ambient mechanical vibration by use of a vibration power generator. As the generator is excited by ambient mechanical vibration, its construction produces a relative movement of a magnetic circuit. This movement induces a current into an electrical coil due to Faraday's law. For

Z. Hadas; M. Kluge; V. Singule; C. Ondrusek

2007-01-01

5

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

Microsoft Academic Search

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

6

A comparison of power output from linear and nonlinear kinetic energy harvesters using real vibration data  

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

7

Vibration Based Electromagnetic Energy Harvesting - Microgenerator, Power Conversion and Control  

NASA Astrophysics Data System (ADS)

Energy harvesting has been a research focus for many years. The idea that energy can be harvested from ambient environment and a device can operate without a battery is very attractive for low power electronic applications. The slow growth of battery technology and development of low power semiconductor technology has positioned energy harvesting as a feasible power source for low power applications. The present work emphasizes on microgenerator design and power processing circuits for electromagnetic energy harvesting. The main objective is to develop a complete system for low voltage electromagnetic energy harvesting. The thesis work has been designed and developed in consecutive stages - (a) novel converter topologies for low voltage microgenerators, (b) unified design of microgenerators and converter topologies, (c) design of efficient auxiliary circuits, (d) optimal energy harvesting control. A number of suitable converter topologies are first presented for low voltage, low power energy harvesting. Their operation, analysis and modeling are discussed in detail. The loss analysis is developed to properly characterize the performance of different converters developed in this thesis. Multiple methods to interface the microgenerator with the converters are presented. Based on the interface mechanism, a suitable unified design approach is also formulated for both the microgenerator and the converters. To realize a self-sufficient energy harvesting system, design of auxiliary circuits like start-up circuits, controller and gate driver circuits is very important. In this work, they are fabricated to consume very low power while satisfying the converter requirements. Finally, a new low power control system is developed to maximize the output of the energy harvesting system. Two types of control are envisaged in this work. The first type is a simpler voltage regulation mechanism. The second, more interesting type of control is based on controlling the converter to maximize the harvested energy from the source.

Dayal, Rohan

8

A MEMS-Based Piezoelectric Power Generator for Low Frequency Vibration Energy Harvesting  

Microsoft Academic Search

A novel power generator has been achieved to convert vibration to electrical energy via the piezoelectric effect. The generator obtained by micro fabrication process mainly consists of silicon based frame and composite cantilever. The prototype tested at resonant vibration generates 1.15 muW of effective power to a 20.4-kOmega resistance load. The potential of this work is to offer miniaturization solutions

Hua-Bin Fang; Jing-Quan Liu; Zheng-Yi Xu; Lu Dong; Di Chen; Bing-Chu Cai; Yue Liu

2006-01-01

9

Self-powered autonomous wireless sensor node using vibration energy harvesting  

Microsoft Academic Search

This paper reports the development and implementation of an energy aware autonomous wireless condition monitoring sensor system (ACMS) powered by ambient vibrations. An electromagnetic (EM) generator has been designed to harvest sufficient energy to power a radio-frequency (RF) linked accelerometer-based sensor system. The ACMS is energy aware and will adjust the measurement\\/transmit duty cycle according to the available energy; this

R. Torah; P. Glynne-Jones; M. Tudor; T. O'Donnell; S. Roy; S. Beeby

2008-01-01

10

Electromagnetic vibration energy harvesting with high power density using a magnet array  

NASA Astrophysics Data System (ADS)

Electromagnetic vibration energy harvesters have been widely used to convert the vibration energy into electricity. However, one of the main challenges of using electromagnetic vibration energy harvesters is that they are usually in very large size with low power density. In this paper, a new type of electromagnetic vibration energy harvester with remarkably high power density is developed. By putting the strong rare-earth magnets in alternating directions and using high-magnetic-conductive casing, magnetic flux density up to 0.9T are obtained. This configuration also has a small current loop with less electrical reluctance, which further increases the high power density when the coil is designed to follow the current loop. The prototype, the size of which is 142x140x86 mm3, can provided up to 727Ns/m damping coefficient, which means 428 kNs/m4 damping density when it is shunt with 70? external resistive load which is set to the same as the internal resistor of the harvester to achieve maximum power. The corresponding power density is 725 ?W/cm3 at 15HZ harmonic force excitation of 2.54mm peak-to-peak amplitude. When shot-circuited, 1091Ns/m damping coefficient and 638 kNs/m4 damping density is achieved. The effectiveness of this novel vibration energy harvester is shown both by FEA and experiments. The eddy current damper is also discussed in this paper for comparison. The proposed configuration of the magnet array can also be extended for both micro-scale and large-scale energy harvesting applications, such as vibration energy harvesting from tall buildings, long bridges and railways.

Tang, Xiudong; Lin, Teng; Zuo, Lei

2012-03-01

11

Fabrication and performance of MEMS-based piezoelectric power generator for vibration energy harvesting  

Microsoft Academic Search

A MEMS-based energy harvesting device, micro piezoelectric power generator, is designed to convert ambient vibration energy to electrical power via piezoelectric effect. In this work, the generator structure of composite cantilever with nickel metal mass is devised. Micro-electronic-mechanical systems (MEMS) related techniques such as sol–gel, RIE dry etching, wet chemical etching, UV-LIGA are developed to fabricate the device and then

Hua-bin Fang; Jing-quan Liu; Zheng-yi Xu; Lu Dong; Li Wang; Di Chen; Bing-chu Cai; Yue Liu

2006-01-01

12

Linear and nonlinear energy harvesters for powering pacemakers from heart beat vibrations  

Microsoft Academic Search

Linear and nonlinear piezoelectric devices are introduced to continuously recharge the batteries of the pacemakers by converting the vibrations from the heartbeats to electrical energy. The power requirement of the pacemakers is very low. At the same time, after about 10 years from the original implantation of the pacemakers, patients have to go through another surgical operation just to replace

M. Amin Karami; Daniel J. Inman

2011-01-01

13

Self-powered resonant frequency tuning for Piezoelectric Vibration Energy Harvesters  

NASA Astrophysics Data System (ADS)

This paper reports on the design, fabrication and testing of an innovative 33-mode piezoelectric vibration energy harvester (VEH). This system is able to change its resonant frequency in real time to follow the main frequency of a vibration source. The system proposed in this paper enables to adapt VEH characteristics (resonant frequency, electrical damping) to vibration parameters variations (frequency and amplitude) in order to optimize the extraction of energy and then the output power at any time. This solution allows up to 40% of resonant frequency tuning ratio; moreover, the adaptation is made in real time and the consumption of the regulation electronic is less than 10% of the VEH output power (480?W@0.1g-276Hz).

Ahmed-Seddik, B.; Despesse, G.; Boisseau, S.; Defay, E.

2013-12-01

14

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

PubMed

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

15

Electromagnetic Energy Harvesting Circuit With Feedforward and Feedback DC–DC PWM Boost Converter for Vibration Power Generator System  

Microsoft Academic Search

This paper presents an integrated vibration power generator system. The system consists of a mini electromagnetic vibration power generator and a highly efficient energy harvesting circuit implemented on a minute printed circuit board and a 0.35-mum CMOS integrated chip. By introducing a feedback control into the dc-dc pulsewidth modulation (PWM) boost converter with feedforward control, the energy harvesting circuit can

Xinping Cao; Wen-Jen Chiang; Ya-Chin King; Yi-Kuen Lee

2007-01-01

16

A MEMS-based piezoelectric power generator array for vibration energy harvesting  

Microsoft Academic Search

Piezoelectric power generator made by microelectromechanical system (MEMS) technology can scavenge power from low-level ambient vibration sources. The developed MEMS power generators are featured with fixed\\/narrow operation frequency and power output in microwatt level, whereas, the frequency of ambient vibration is floating in some range, and power output is insufficient. In this paper, a power generator array based on thick-film

Jing-Quan Liu; Hua-Bin Fang; Zheng-Yi Xu; Xin-Hui Mao; Xiu-Cheng Shen; Di Chen; Hang Liao; Bing-Chu Cai

2008-01-01

17

Multi-modal vibration based MEMS energy harvesters for ultra-low power wireless functional nodes  

NASA Astrophysics Data System (ADS)

The aim of this contribution is to report and discuss a preliminary study and rough optimization of a novel concept of MEMS device for vibration energy harvesting, based on a multi-modal dynamic behavior. The circular-shaped device features Four-Leaf Clover-like (FLC) double spring-mass cascaded systems, kept constrained to the surrounding frame by means of four straight beams. The combination of flexural bending behavior of the slender beams plus deformable parts of the petals enable to populate the desired vibration frequency range with a number of resonant modes, and improve the energy conversion capability of the micro-transducer. The harvester device, conceived for piezoelectric mechanical into electric energy conversion, is intended to sense environmental vibrations and, thereby, its geometry is optimized to have a large concentration of resonant modes in a frequency range below 5-10 kHz. The results of FEM (Finite Element Method) based analysis performed in ANSYSTM Workbench are reported, both concerning modal and harmonic response, providing important indications related to the device geometry optimization. The analysis reported in this work is limited to the sole mechanical modeling of the proposed MEMS harvester device concept. Future developments of the study will encompass the inclusion of piezoelectric conversion in the FEM simulations, in order to have indications of the actual power levels achievable with the proposed harvester concept. Furthermore, the results of the FEM studies here discussed, will be validated against experimental data, as soon as the MEMS resonator specimens, currently under fabrication, are ready for testing.

Iannacci, J.; Gottardi, M.; Serra, E.; Di Criscienzo, R.; Borrielli, A.; Bonaldi, M.

2013-05-01

18

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

2007-03-01

19

A vibration energy harvesting device with bidirectional resonance frequency tunability  

Microsoft Academic Search

Vibration energy harvesting is an attractive technique for potential powering of wireless sensors and low power devices. While the technique can be employed to harvest energy from vibrations and vibrating structures, a general requirement independent of the energy transfer mechanism is that the vibration energy harvesting device operate in resonance at the excitation frequency. Most energy harvesting devices developed to

Vinod R Challa; M G Prasad; Yong Shi; Frank T Fisher

2008-01-01

20

Energy Harvesters Driven by Broadband Random Vibrations  

Microsoft Academic Search

Simple analytical models have proved very useful in understanding vibration energy harvesters driven by a sinusoidal acceleration. Corresponding analyses for broadband excitations have been absent. In this paper, we present new closed-form results on the output power, proof mass displacement, and optimal load of linear resonant energy harvesters driven by broadband vibrations. Output power dependence on signal bandwidth is also

Einar Halvorsen

2008-01-01

21

A three-dimensional electret-based micro power generator for low-level ambient vibrational energy harvesting  

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

22

A broadband vibrational energy harvester  

NASA Astrophysics Data System (ADS)

We propose a design for an energy harvester which has the potential to harvest vibrational energy over a broad range of ambient frequencies. The device uses two flexible ceramic piezoelectric elements arranged in a buckled configuration in the absence of vibrations. Experimental data show that this design allows enhanced harvesting of energy relative to a comparable cantilever design, both for periodic and stochastic vibrations. Moreover, the data suggest that this harvester has its peak energy generation when it responds with chaotic vibrations.

Van Blarigan, Louis; Danzl, Per; Moehlis, Jeff

2012-06-01

23

Design and fabrication of vibration based energy harvester using microelectromechanical system piezoelectric cantilever for low power applications.  

PubMed

We fabricated dual-beam cantilevers on the microelectromechanical system (MEMS) scale with an integrated Si proof mass. A Pb(Zr,Ti)O3 (PZT) cantilever was designed as a mechanical vibration energy-harvesting system for low power applications. The resonant frequency of the multilayer composition cantilevers were simulated using the finite element method (FEM) with parametric analysis carried out in the design process. According to simulations, the resonant frequency, voltage, and average power of a dual-beam cantilever was 69.1 Hz, 113.9 mV, and 0.303 microW, respectively, at optimal resistance and 0.5 g (gravitational acceleration, m/s2). Based on these data, we subsequently fabricated cantilever devices using dual-beam cantilevers. The harvested power density of the dual-beam cantilever compared favorably with the simulation. Experiments revealed the resonant frequency, voltage, and average power density to be 78.7 Hz, 118.5 mV, and 0.34 microW, respectively. The error between the measured and simulated results was about 10%. The maximum average power and power density of the fabricated dual-beam cantilever at 1 g were 0.803 microW and 1322.80 microW cm(-3), respectively. Furthermore, the possibility of a MEMS-scale power source for energy conversion experiments was also tested. PMID:24266167

Kim, Moonkeun; Lee, Sang-Kyun; Yang, Yil Suk; Jeong, Jaehwa; Min, Nam Ki; Kwon, Kwang-Ho

2013-12-01

24

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

25

Nonlinear vibration energy harvester using diamagnetic levitation  

NASA Astrophysics Data System (ADS)

This letter proposes a nonlinear vibration energy harvester based on stabilized magnetic levitation using diamagnetic. Restoring forces induced by the magnetic field in harvesting vibration energy is employed instead of the forces introduced by conventional mechanical suspensions; therefore dissipation of vibration energy into heat through mechanical suspensions is eliminated. The core of the design consists of two spiral coils made of diamagnetic materials, which serve dual purposes: providing nonlinear restoring force and harnessing eddy current to power external circuits. From the theoretical analysis presented, the proposed harvester has the potential to provide wideband power outputs in low frequency range.

Liu, L.; Yuan, F. G.

2011-05-01

26

On energy harvesting from ambient vibration  

Microsoft Academic Search

Future MEMS devices will harvest energy from their environment. One can envisage an autonomous condition monitoring vibration sensor being powered by that same vibration, and transmitting data over a wireless link; inaccessible or hostile environments are obvious areas of application. The base excitation of an elastically mounted magnetic seismic mass moving past a coil, considered previously by several authors, is

N. G. Stephen

2006-01-01

27

Measuring vibration characteristics at large amplitude region of materials for high power ultrasonic vibration system  

PubMed

This study proposes a method of estimating the mechanical quality factor of materials for high-power ultrasonic vibration systems under large vibration amplitude conditions. The quality factors of several metals as well as some polymers are measured by this method. In this method, the quality factor is calculated as the ratio of the reactive energy stored in a specimen to the dissipated energy. The dissipated energy is estimated from the input/output mechanical energy to the specimen by measurement of the vibration intensity, while the reactive energy is measured as the kinetic energy of the vibration. Then, the quality factor for the specified part can be extracted using this method. In this report, quality factors for torsional vibration were measured at about 30 kHz as functions of the vibration strain. PMID:10829642

Nakamura; Kakihara; Kawakami; Ueha

2000-03-01

28

An energy harvesting system using the wind-induced vibration of a stay cable for powering a wireless sensor node  

NASA Astrophysics Data System (ADS)

This paper proposes an electromagnetic energy harvesting system, which utilizes the wind-induced vibration of a stay cable, and investigates its feasibility for powering a wireless sensor node on the cable through numerical simulations as well as experimental tests. To this end, the ambient acceleration responses of a stay cable installed in an in-service cable-stayed bridge are measured, and then they are used as input excitations in cases of both numerical simulations and experimental tests to evaluate the performance of the proposed energy harvesting system. The results of the feasibility test demonstrate that the proposed system generates sufficient electricity for operation of a wireless sensor node attached on the cable under the moderate wind conditions.

Jung, Hyung-Jo; Kim, In-Ho; Jang, Seon-Jun

2011-07-01

29

Wideband excitation of an electrostatic vibration energy harvester with power-extracting end-stops  

NASA Astrophysics Data System (ADS)

An electrostatic energy harvester with two-stage transduction is investigated for enhancement of bandwidth and dynamic range. The harvester includes a primary proof mass with two main transducers and end-stops for the proof mass functioning as secondary transducers. In the small acceleration regime, the power is primarily obtained from the main transducers. In the high acceleration regime, the mass impacts the end-stops and actuates the secondary transducers, generating additional output power. The device is designed and fabricated using the SOIMUMPs process and has a total active area of 4 × 5 mm2. Under wideband acceleration at high levels, the experimental results show that the total output power increases to about twice the output power of the main transducers, while the 3 dB-bandwidth is enlarged by a factor of 6.7 compared to the linear-response bandwidth at low levels. In comparison with a reference device made with the same die dimensions, the two-stage device improves output power instead of saturating when the maximum mass displacements of both devices reach the same limit. Measurement of output power demonstrates that the device with the transducing end-stops give an efficiency of 23.6%, while this value is 14.1% for the reference device with the conventional end-stops, at an acceleration spectral density of Sa = 19.2 × 10-3 g2 Hz-1. The efficiency is improved about by 9.5% in the impact regime.

Phu Le, Cuong; Halvorsen, Einar; Søråsen, Oddvar; Yeatman, Eric M.

2013-07-01

30

Vibration energy harvester optimization using artificial intelligence  

NASA Astrophysics Data System (ADS)

This paper deals with an optimization study of a vibration energy harvester. This harvester can be used as autonomous source of electrical energy for remote or wireless applications, which are placed in environment excited by ambient mechanical vibrations. The ambient energy of vibrations is usually on very low level but the harvester can be used as alternative source of energy for electronic devices with an expected low level of power consumption of several mW. The optimized design of the vibration energy harvester was based on previous development and the sensitivity of harvester design was improved for effective harvesting from mechanical vibrations in aeronautic applications. The vibration energy harvester is a mechatronic system which generates electrical energy from ambient vibrations due to precision tuning up generator parameters. The optimization study for maximization of harvested power or minimization of volume and weight are the main goals of our development. The optimization study of such complex device is complicated therefore artificial intelligence methods can be used for tuning up optimal harvester parameters.

Hadas, Z.; Ondrusek, C.; Kurfurst, J.; Singule, V.

2011-05-01

31

Energy scavenging from environmental vibration.  

SciTech Connect

The goal of this project is to develop an efficient energy scavenger for converting ambient low-frequency vibrations into electrical power. In order to achieve this a novel inertial micro power generator architecture has been developed that utilizes the bi-stable motion of a mechanical mass to convert a broad range of low-frequency (< 30Hz), and large-deflection (>250 {micro}m) ambient vibrations into high-frequency electrical output energy. The generator incorporates a bi-stable mechanical structure to initiate high-frequency mechanical oscillations in an electromagnetic scavenger. This frequency up-conversion technique enhances the electromechanical coupling and increases the generated power. This architecture is called the Parametric Frequency Increased Generator (PFIG). Three generations of the device have been fabricated. It was first demonstrated using a larger bench-top prototype that had a functional volume of 3.7cm3. It generated a peak power of 558{micro}W and an average power of 39.5{micro}W at an input acceleration of 1g applied at 10 Hz. The performance of this device has still not been matched by any other reported work. It yielded the best power density and efficiency for any scavenger operating from low-frequency (<10Hz) vibrations. A second-generation device was then fabricated. It generated a peak power of 288{micro}W and an average power of 5.8{micro}W from an input acceleration of 9.8m/s{sup 2} at 10Hz. The device operates over a frequency range of 20Hz. The internal volume of the generator is 2.1cm{sup 3} (3.7cm{sup 3} including casing), half of a standard AA battery. Lastly, a piezoelectric version of the PFIG is currently being developed. This device clearly demonstrates one of the key features of the PFIG architecture, namely that it is suitable for MEMS integration, more so than resonant generators, by incorporating a brittle bulk piezoelectric ceramic. This is the first micro-scale piezoelectric generator capable of <10Hz operation. The fabricated device currently generates a peak power of 25.9{micro}W and an average power of 1.21{micro}W from an input acceleration of 9.8m/s{sup -} at 10Hz. The device operates over a frequency range of 23Hz. The internal volume of the generator is 1.2cm{sup 3}.

Galchev, Tzeno (University of Michigan); Apblett, Christopher Alan; Najafi, Khalil (University of Michigan)

2009-10-01

32

Vortex vibration for clean power  

Microsoft Academic Search

In this millennium decade, there may be numerous methods to produce energy other than conventional methods, like solar power production, geothermal power production etc. But each type fails in their own accords either in one or more aspects like cost, efficiency, endurance, tolerance, reliability etc. To counteract these problems, we came up with new technology. Ours is a very novel

M. Kamal Raj; B. Gowtham Muthuraj

2011-01-01

33

Vibration based energy harvesting using piezoelectric material  

Microsoft Academic Search

Energy harvesting has been around for centuries in the form of windmills, watermills and passive solar power systems. It is not only restricted to the natural resources but it has widen the tapping source to utilise the vibration which happen all around us. In the last decade, beam with piezoceramic patches have been used as a method to harverst energy.

M. N Fakhzan; Asan G. A. Muthalif

2011-01-01

34

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

35

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

36

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

37

Wideband vibration energy harvester with high permeability magnetic material  

Microsoft Academic Search

A vibration energy harvester based on a high permeability cantilever beam was demonstrated, which overcomes the limitation of the existing approaches in output power and working bandwidth. Magnetostatic coupling between the vibrating highly permeable beam and bias magnetic field leads to maximized flux change and large induced voltage. The coexistence of magnetostatic and elastic potential energy results in the nonlinear

X. Xing; J. Lou; G. M. Yang; O. Obi; C. Driscoll; N. X. Sun

2009-01-01

38

Vibration energy harvesting by magnetostrictive material  

NASA Astrophysics Data System (ADS)

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 vibrations. To enhance the energy conversion efficiency and alleviate the need of a bias magnetic field, Metglas ribbons are transversely annealed by a strong magnetic field along their width direction. To analyze the MsM harvesting device a generalized electromechanical circuit model is derived from Hamilton's principle in conjunction with the normal mode superposition method based on Euler-Bernoulli beam theory. The MsM harvesting device is equivalent to an electromechanical gyrator in series with an inductor. In addition, the proposed model can be readily extended to a more practical case of a cantilever beam element with a tip mass. The energy harvesting circuit, which interfaces with a wireless sensor and accumulates the harvested energy into an ultracapacitor, is designed on a printed circuit board (PCB) with plane dimension 25 mm × 35 mm. It mainly consists of a voltage quadrupler, a 3 F ultracapacitor and a smart regulator. The output DC voltage from the PCB can be adjusted within 2.0-5.5 V. In experiments, the maximum output power and power density on the resistor can reach 200 µW and 900 µW cm-3, respectively, at a low frequency of 58 Hz. For a working prototype under a vibration with resonance frequency of 1.1 kHz and peak acceleration of 8.06 m s-2 (0.82 g), the average power and power density during charging the ultracapacitor can achieve 576 µW and 606 µW cm-3, respectively, which compete favorably with piezoelectric vibration energy harvesters.

Wang, Lei; Yuan, F. G.

2008-08-01

39

Self-powered active vibration control using a single electric actuator  

Microsoft Academic Search

The authors have proposed self-powered active vibration control systems that achieve active vibration control using regenerated vibration energy. Such systems do not require external energy to produce a control force. This paper presents a self-powered system in which a single actuator realizes active control and energy regeneration.The system proposed needs to regenerate more energy than it consumes. To discuss the

Kimihiko Nakano; Yoshihiro Suda; Shigeyuki Nakadai

2003-01-01

40

Piezoelectric Vibration Energy Harvesting Device.  

National Technical Information Service (NTIS)

A piezoelectric vibration energy harvesting device which is made up of a first mass, a second, a first spring coupled to the first mass, and a second spring coupled to the second mass. A piezoelectric element is bonded between the first mass and the secon...

K. Andic K. K. Deng

2005-01-01

41

Nonlinear vibration energy harvester using diamagnetic levitation  

Microsoft Academic Search

This letter proposes a nonlinear vibration energy harvester based on stabilized magnetic levitation using diamagnetic. Restoring forces induced by the magnetic field in harvesting vibration energy is employed instead of the forces introduced by conventional mechanical suspensions; therefore dissipation of vibration energy into heat through mechanical suspensions is eliminated. The core of the design consists of two spiral coils made

L. Liu; F. G. Yuan

2011-01-01

42

A wideband vibration-based energy harvester  

Microsoft Academic Search

We present a new architecture for wideband vibration-based micro-power generators (MPGs). It replaces a linear oscillator with a piecewise-linear oscillator as the energy harvesting element of the MPG. A prototype of an electromagnetic MPG designed accordingly is analyzed analytically, numerically and experimentally. We find that the new architecture increases the bandwidth of the MPG during a frequency up-sweep, while maintaining

M S M Soliman; E M Abdel-Rahman; E F El-Saadany; R R Mansour

2008-01-01

43

Energy scavenging from low frequency vibrations  

NASA Astrophysics Data System (ADS)

The development of three energy conversion devices that are able to transform vibrations in their surroundings to electrical energy is discussed in this thesis. These energy harvesters are based upon a newly invented architecture called the Parametric Frequency Increased Generator (PFIG). The PFIG structure is designed to efficiently convert low frequency and non-periodic vibrations into electrical power. The three PFIG devices have a combined operating range covering two orders of magnitude in acceleration (0.54--19.6m/s 2) and a frequency range spanning up to 60Hz; making them some of the most versatile generators in existence. The PFIG utilizes a bi-stable mechanical structure to initiate high-frequency mechanical oscillations in an electromechanical scavenger. By up-converting the ambient vibration frequency to a higher internal operation frequency, the PFIG achieves better electromechanical coupling. The fixed internal displacement and dynamics of the PFIG allow it to operate more efficiently than resonant generators when the ambient vibration amplitude is higher than the internal displacement limit of the device. The PFIG structure is capable of efficiently converting mechanical vibrations with variable characteristics including amplitude and frequency, into electrical power. The first electromagnetic harvester can generate a peak power of 163microW and an average power of 13.6microW from an input acceleration of 9.8m/s 2 at 10Hz, and it can operate up to 60Hz. The internal volume of the generator is 2.12cm3 (3.75 including casing). It sets the state-of-the-art in efficiency in the <20Hz range. The volume figure of merit is 0.068%, which is a 10x improvement over other published works. It has a record high bandwidth figure of merit (0.375%). A second piezoelectric implementation generates 3.25microW of average power under the same excitation conditions, while the volume of the generator is halved (1.2cm3). A third PFIG was developed for critical infrastructure monitoring applications. It is used to harvest the very low-amplitude, low-frequency, and non-periodic vibrations present on bridges. The device generates 2.3microW of average power from an input acceleration of 0.54m/s2 at only 2Hz. The internal volume of the generator is 43cm3. It can operate over an unprecedentedly large acceleration (0.54--9.8m/s2) and frequency range (up to 30Hz) without any modifications or tuning.

Galchev, Tzeno V.

44

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

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

A magnetically levitated vibration energy harvester  

NASA Astrophysics Data System (ADS)

In this paper a novel electromagnetic vibration type energy harvester that uses a diamagnetic levitation system is conceptualized, designed, fabricated, and tested. The harvester uses two diamagnetic plates made of pyrolytic graphite between which a cylindrical magnet levitates passively. Two thick cylindrical coils, placed in grooves which are engraved in the pyrolytic graphite plates, are used to convert the mechanical energy into electrical energy efficiently. The geometric configurations of the coils are selected based on the field distribution of the magnet to enhance the efficiency of the harvester. A thorough theoretical analysis is carried out to compare with experimental results. At an input power of 103.45 ?W and at a frequency of 2.7 Hz, the harvester generated a power of 0.74 ?W with a system efficiency of 0.72%. Both theoretical and experimental results show that this new energy harvesting system can capture low frequency broadband spectra.

Wang, X. Y.; Palagummi, S.; Liu, L.; Yuan, F. G.

2013-05-01

47

A vibration energy harvester using diamagnetic levitation  

NASA Astrophysics Data System (ADS)

In this paper a novel electromagnetic vibration type energy harvester which uses a diamagnetic levitation system is conceptualized, designed, fabricated, and tested. The harvester uses two diamagnetic plates made of pyrolytic graphite between which a cylindrical magnet levitates passively. Two archimedean spiral coils are placed in grooves which are engraved in the pyrolytic graphite plates, used to convert the mechanical energy into electrical energy efficiently. The geometric configurations of coils are selected based on the field distribution of the magnet to enhance the efficiency of the harvester. A thorough theoretical analysis is done to compare with the experiment results. At an input power of 103.45 ?W and at a frequency of 2.7 Hz, the harvester generated a power of 0.744 ?W at an efficiency of 0.72 %. Both theoretical and experimental results show that this new energy harvesting system is efficient and can capture low frequency broadband spectra.

Palagummi, S.; Yuan, F. G.

2013-04-01

48

Vibration energy harvesting for unmanned aerial vehicles  

NASA Astrophysics Data System (ADS)

Unmanned aerial vehicles (UAVs) are a critical component of many military operations. Over the last few decades, the evolution of UAVs has given rise to increasingly smaller aircraft. Along with the development of smaller UAVs, termed mini UAVs, has come issues involving the endurance of the aircraft. Endurance in mini UAVs is problematic because of the limited size of the fuel systems that can be incorporated into the aircraft. A large portion of the total mass of many electric powered mini UAVs, for example, is the rechargeable battery power source. Energy harvesting is an attractive technology for mini UAVs because it offers the potential to increase their endurance without adding significant mass or the need to increase the size of the fuel system. This paper investigates the possibility of harvesting vibration and solar energy in a mini UAV. Experimentation has been carried out on a remote controlled (RC) glider aircraft with a 1.8 m wing span. This aircraft was chosen to replicate the current electric mini UAVs used by the military today. The RC glider was modified to include two piezoelectric patches placed at the roots of the wings and a cantilevered piezoelectric beam installed in the fuselage to harvest energy from wing vibrations and rigid body motions of the aircraft, as well as two thin film photovoltaic panels attached to the top of the wings to harvest energy from sunlight. Flight testing has been performed and the power output of the piezoelectric and photovoltaic devices has been examined.

Anton, Steven R.; Inman, Daniel J.

2008-05-01

49

Electrostatic micro power generation from low-frequency vibration such as human motion  

NASA Astrophysics Data System (ADS)

We developed an electrostatic micro power generator for low-frequency energy harvesting applications. This micro power generator consists of a new vibration structure and a new electret structure (stripe masked electret). The advantage of this micro power generator is the high power generation structure of both the controlled gap between electrodes and long-range movement at low frequency. This generator shows 40 µW of power output at very low frequency vibration (2 Hz, 0.4 G).

Naruse, Y.; Matsubara, N.; Mabuchi, K.; Izumi, M.; Suzuki, S.

2009-09-01

50

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

51

Vibrational energy relaxation of large-amplitude vibrations in liquids  

NASA Astrophysics Data System (ADS)

Given the limited intermolecular spaces available in dense liquids, the large amplitudes of highly excited, low frequency vibrational modes pose an interesting dilemma for large molecules in solution. We carry out molecular dynamics calculations of the lowest frequency (``warping'') mode of perylene dissolved in liquid argon, and demonstrate that vibrational excitation of this mode should cause identifiable changes in local solvation shell structure. But while the same kinds of solvent structural rearrangements can cause the non-equilibrium relaxation dynamics of highly excited diatomic rotors in liquids to differ substantially from equilibrium dynamics, our simulations also indicate that the non-equilibrium vibrational energy relaxation of large-amplitude vibrational overtones in liquids should show no such deviations from linear response. This observation seems to be a generic feature of large-moment-arm vibrational degrees of freedom and is therefore probably not specific to our choice of model system: The lowest frequency (largest amplitude) cases probably dissipate energy too quickly and the higher frequency (more slowly relaxing) cases most likely have solvent displacements too small to generate significant nonlinearities in simple nonpolar solvents. Vibrational kinetic energy relaxation, in particular, seems to be especially and surprisingly linear.

Zhang, Baofeng; Stratt, Richard M.

2012-07-01

52

A retrofitted energy harvester for low frequency vibrations  

Microsoft Academic Search

Piezoelectric-based energy harvesting is an efficient way to convert ambient vibration energy into usable electric energy. However, its output power drops steeply with reducing excitation frequency. To improve the harvesting performance at low frequencies, a multi-impact harvester is proposed in this paper. The proposed design consists of a hung mass and two stiff piezoelectric cantilever beams. A series of impacts

Ye Zhang; C S Cai

2012-01-01

53

Adaptive Vibration Reduction System Shown to Effectively Eliminate Vibrations for the Stirling Radioisotope Power System  

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

54

Design of nonlinear springs for wideband magnetic vibration energy harvester  

Microsoft Academic Search

This paper compares four nonlinear springs for the micro power generator (MPG) application which convert low level vibration energy into electrical power. The magnet-spring system decides the generator's resonant frequency, and this work proves that the spring's nonlinearity level influences the width of the operating frequency. The four different planar springs have the same outer\\/inner dimensions and the same linear

Linghe Sui; Xuhan Dai; Xiaolin Zhao; Peihong Wang; Hailin Zhou

2011-01-01

55

A micro electromagnetic generator for vibration energy harvesting  

Microsoft Academic Search

Vibration energy harvesting is receiving a considerable amount of interest as a means for powering wireless sensor nodes. This paper presents a small (component volume 0.1 cm3, practical volume 0.15 cm3) electromagnetic generator utilizing discrete components and optimized for a low ambient vibration level based upon real application data. The generator uses four magnets arranged on an etched cantilever with

S P Beeby; R N Torah; M J Tudor; P Glynne-Jones; T O'Donnell; C R Saha; S Roy

2007-01-01

56

Novel vibration-driven micro-electrostatic induction energy harvester with asymmetric multi-resonant spring  

Microsoft Academic Search

We developed an asymmetric gammadion spring electrode for wide band vibration as a counter electrode for the electret electrode film of a micro electrostatic energy harvester. A vibration-driven micro power generator with a high-Q mechanical resonator works efficiently under single-frequency vibration, but, the associated narrow operation frequency bandwidth tightly limits the power output under normal wideband vibrations. To solve this

Takafumi Suzuki; Sumito Nagasawa; Hiroshi Okamoto; Hiroki Kuwano

2010-01-01

57

Vibration Monitoring of Power Distribution Poles  

SciTech Connect

Some of the most visible and least monitored elements of our national security infrastructure are the poles and towers used for the distribution of our nation’s electrical power. Issues surrounding these elements within the United States include safety such as unauthorized climbing and access, vandalism such as nut/bolt removal or destructive small arms fire, and major vandalism such as the downing of power poles and towers by the cutting of the poles with a chainsaw or torches. The Idaho National Laboratory (INL) has an ongoing research program working to develop inexpensive and sensitive sensor platforms for the monitoring and characterization of damage to the power distribution infrastructure. This presentation covers the results from the instrumentation of a variety of power poles and wires with geophone assemblies and the recording of vibration data when power poles were subjected to a variety of stimuli. Initial results indicate that, for the majority of attacks against power poles, the resulting signal can be seen not only on the targeted pole but on sensors several poles away in the distribution network and a distributed sensor system can be used to monitor remote and critical structures.

Clark Scott; Gail Heath; John Svoboda

2006-04-01

58

Harmonic-resonator-based triboelectric nanogenerator as a sustainable power source and a self-powered active vibration sensor.  

PubMed

A harmonic-resonator-based triboelectric nanogenerator (TENG) is presented as a sustainable power source and an active vibration sensor. It can effectively respond to vibration frequencies ranging from 2 to 200 Hz with a considerably wide working bandwidth of 13.4 Hz. This work not only presents a new principle in the field of vibration energy harvesting but also greatly expands the applicability of TENGs. PMID:23999798

Chen, Jun; Zhu, Guang; Yang, Weiqing; Jing, Qingshen; Bai, Peng; Yang, Ya; Hou, Te-Chien; Wang, Zhong Lin

2013-11-13

59

Vibration characteristics about thermal variation of BFP in power plant  

NASA Astrophysics Data System (ADS)

BFPs(Boiler Feedwater Pump) in power plants are used for pumping high pressure and high temperature water. The pressure pulsation of high pressure pumps is the vibration caused by fluid forces. If the frequency of the exciting source is adjacent to one of the natural frequencies of the pump, it can cause high vibration by resonance. The natural vibration characteristics of pump depend on thermal variation. This paper examines vibration characteristics due to thermal variation experimentally and analytically.

Song, A. H.; Song, J. D.; Kim, H. S.; Jung, G. C.

2012-11-01

60

Energy flow analysis in vibrating systems by laser vibrometer measurements  

Microsoft Academic Search

In this paper an experimental analysis of the energy transmission in vibrating structures is considered. The classical discretization techniques (FEM, BEM) fail when one tries to solve high-frequency dynamic problems. At present, SEA is the most acknowledged theory for providing such kind of solution, giving information on the stored mechanical energy and on the dissipated mechanical power between the modal

Antonio Culla; Aldo Sestieri

2002-01-01

61

Electrostatic micro power generation from low-frequency vibration such as human motion  

Microsoft Academic Search

We developed an electrostatic micro power generator for low-frequency energy harvesting applications. This micro power generator consists of a new vibration structure and a new electret structure (stripe masked electret). The advantage of this micro power generator is the high power generation structure of both the controlled gap between electrodes and long-range movement at low frequency. This generator shows 40

Y. Naruse; N. Matsubara; K. Mabuchi; M. Izumi; S. Suzuki

2009-01-01

62

A wideband vibration-based energy harvester  

NASA Astrophysics Data System (ADS)

We present a new architecture for wideband vibration-based micro-power generators (MPGs). It replaces a linear oscillator with a piecewise-linear oscillator as the energy harvesting element of the MPG. A prototype of an electromagnetic MPG designed accordingly is analyzed analytically, numerically and experimentally. We find that the new architecture increases the bandwidth of the MPG during a frequency up-sweep, while maintaining the same bandwidth in a down-sweep. Closed-form expressions for the response of the new MPG as well as the up-sweep bandwidth are presented and validated experimentally. Simulations show that under random-frequency excitations, the new MPG collects more energy than the traditional MPG.

Soliman, M. S. M.; Abdel-Rahman, E. M.; El-Saadany, E. F.; Mansour, R. R.

2008-11-01

63

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

64

Piezoelectric MEMS Energy Harvester for Low-Frequency Vibrations With Wideband Operation Range and Steadily Increased Output Power  

Microsoft Academic Search

A piezoelectric MEMS energy harvester (EH) with low resonant frequency and wide operation bandwidth was de- signed, microfabricated, and characterized. The MEMS piezo- electric energy harvesting cantilever consists of a silicon beam integrated with piezoelectric thin film (PZT) elements parallel- arranged on top and a silicon proof mass resulting in a low resonant frequency of 36 Hz. The whole chip

Huicong Liu; Cho Jui Tay; Chenggen Quan; Takeshi Kobayashi; Chengkuo Lee

2011-01-01

65

A vibration energy harvesting sensor platform for increased industrial efficiency  

Microsoft Academic Search

A model for piezoelectric vibration energy harvesting with a piezoelectric cantilever beam is presented. The model incorporates expressions for variable geometry, tip mass, and material constants, and allows the parameterized determination of the voltage and power produced over a purely resistive load. The model is of a lumped-element form, with the base excitation acceleration and voltage representing the effort variables,

Todd A. Anderson; Daniel W. Sexton

2006-01-01

66

A Vibration Energy Harvesting Sensor Platform for Increased Industrial Efficiency  

Microsoft Academic Search

A model for piezoelectric vibration energy harvesting with a piezoelectric cantilever beam is presented. The model incorporates expressions for variable geometry, tip mass, and material constants, and allows the parameterized determination of the voltage and power produced over a purely resistive load. The model is of a lumped-element form, with the base excitation acceleration and voltage representing the effort variables,

Todd A. Anderson; Daniel W. Sexton

2006-01-01

67

MEMS generator of power harvesting by vibrations using piezoelectric cantilever beam with digitate electrode  

Microsoft Academic Search

Over the years, there has been a growing interest in the field of power harvesting technologies for low-power electronic devices, such as wireless sensor networks and biomedical sensor applications. Of all possible energy sources, the mechanical vibrations have been considered a potential choice for power harvesting in a wide variety of applications. This paper presents the development of a piezoelectric

Bor-Shun Lee; Jyun-Jhang He; Wen-Jong Wu; Wen-Pin Shih

2006-01-01

68

Direct observation of vibrational energy flow in cytochrome c.  

PubMed

Vibrational energy flow in ferric cytochrome c has been examined by picosecond time-resolved anti-Stokes ultraviolet resonance Raman (UVRR) measurements. By taking advantage of the extremely short nonradiative excited state lifetime of heme in the protein (< ps), excess vibrational energy of 20000-25000 cm(-1) was optically deposited selectively at the heme site. Subsequent energy relaxation in the protein moiety was investigated by monitoring the anti-Stokes UVRR intensities of the Trp59 residue, which is a single tryptophan residue involved in the protein that is located close to the heme group. It was found from temporal changes of the anti-Stokes UVRR intensities that the energy flow from the heme to Trp59 and the energy release from Trp59 took place with the time constants of 1-3 and ~8 ps, respectively. These data are consistent with the time constants for the vibrational relaxation of the heme and heating of water reported for hemeproteins. The kinetics of the energy flow were not affected by the amount of excess energy deposited at the heme group. These results demonstrate that the present technique is a powerful tool for studying the vibrational energy flow in proteins. PMID:21974717

Fujii, Naoki; Mizuno, Misao; Mizutani, Yasuhisa

2011-11-10

69

A low frequency vibration energy harvester using magnetoelectric laminate composite  

NASA Astrophysics Data System (ADS)

In this paper, we present a vibration energy harvester using magnetoelectric laminate composite and a springless spherical permanent magnet as a proof mass. The harvester utilizes a freely movable spherical permanent magnet to transform external vibration into a time varying magnetic field applied to the magnetoelectric transducer. The laminate composite consists of a Ni-Mn-Ga-based MSMA (magnetic shape memory alloy) element and a PZT (lead zirconate titanate) plate. A proof-of-concept harvester has been fabricated and characterized at various input accelerations and frequencies. A maximum open circuit voltage of 1.18 V has been obtained in response to a 3g vibration at 17 Hz with the fabricated device. Moreover, a maximum output voltage of 10.24 V and output power of 4.1 ?W have been achieved on a 950 ? load, when the fabricated energy harvester was mounted on a smartphone and shaken by hand.

Ju, Suna; Chae, Song Hee; Choi, Yunhee; Lee, Seungjun; Lee, Hyang Woon; Ji, Chang-Hyeon

2013-11-01

70

Wideband vibration energy harvester with high permeability magnetic material  

NASA Astrophysics Data System (ADS)

A vibration energy harvester based on a high permeability cantilever beam was demonstrated, which overcomes the limitation of the existing approaches in output power and working bandwidth. Magnetostatic coupling between the vibrating highly permeable beam and bias magnetic field leads to maximized flux change and large induced voltage. The coexistence of magnetostatic and elastic potential energy results in the nonlinear oscillation with wide bandwidth. The harvester showed a maximum power of 74 mW and power density of 1.07 mW/cm3 at 54 Hz under acceleration of 0.57 g (with g=9.8 m/s2), and bandwidth of 10 Hz (or 18.5% of the operating frequency).

Xing, X.; Lou, J.; Yang, G. M.; Obi, O.; Driscoll, C.; Sun, N. X.

2009-09-01

71

Analytical and experimental comparisons of electromechanical vibration response of a piezoelectric bimorph beam for power harvesting  

Microsoft Academic Search

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

M. F. Lumentut; I. M. Howard

72

The bandwidth of optimized nonlinear vibration-based energy harvesters  

NASA Astrophysics Data System (ADS)

In an attempt to improve the performance of vibration-based energy harvesters, many authors suggest that nonlinearities can be exploited to increase the bandwidths of linear devices. Nevertheless, the complex dependence of the response upon the input excitation has made a realistic comparison of linear harvesters with nonlinear energy harvesters challenging. In a previous work it has been demonstrated that for a given frequency of excitation, it is possible to achieve the same maximum power for a nonlinear harvester as that for a linear harvester, provided that the resistance and the linear stiffness of both are optimized. This work focuses on the bandwidths of linear and nonlinear harvesters and shows which device is more suitable for harvesting energy from vibrations. The work considers different levels of excitation as well as different frequencies of excitation. In addition, the effect of the mechanical damping of the oscillator on the power bandwidth is shown for both the linear and nonlinear cases.

Cammarano, A.; Neild, S. A.; Burrow, S. G.; Inman, D. J.

2014-05-01

73

Mechanical vibration to electrical energy converter  

DOEpatents

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

Piezoelectric buckled beams for random vibration energy harvesting  

NASA Astrophysics Data System (ADS)

Among the main vibration-to-electricity conversion systems, resonant harvesters suffer from a series of strong limits like their narrow frequency response and poor output power at small scale. Most of all, realistic vibration sources are variable in time and abundant at relatively low frequencies. Nonlinear vibration harvesters, on the other hand, are more attractive, thanks to their large bandwidth response and flexibility to convert kinetic energy of the natural frequency of the sources. In particular, bistable oscillators have been proven to show higher global performances when excited by random vibrations. In this paper, such an approach is investigated for piezoelectric beams by exerting an increasing axial compression. An advantage of this technique is the absence of magnetic forces to create bistable dynamics. A thin piezoelectric axially loaded beam is theoretically modelled and experimentally investigated under wideband random vibrations. In the buckled configuration, the device exhibits superior power generation over a large interval of resistive load, with gains up to more than a factor of ten compared to the unbuckled state. The numerical model and experimental results are in good qualitative agreement.

Cottone, F.; Gammaitoni, L.; Vocca, H.; Ferrari, M.; Ferrari, V.

2012-03-01

75

Vibration energy harvesting by magnetostrictive material  

Microsoft Academic Search

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

Low Head, Vortex Induced Vibrations River Energy Converter.  

National Technical Information Service (NTIS)

Vortex Induced Vibrations Aquatic Clean Energy (VIVACE) is a novel, demonstrated approach to extracting energy from water currents. This invention is based on a phenomenon called Vortex Induced Vibrations (VIV), which was first observed by Leonardo da Vin...

D. Bernitsas T. Dritz

2006-01-01

77

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

78

Piezoelectric MEMS energy harvesting systems driven by harmonic and random vibrations.  

PubMed

Switching power conditioning techniques are known to greatly enhance the performance of linear piezoelectric energy harvesters subject to harmonic vibrations. With such circuits, little is known about the effect of mechanical stoppers that limit the motion or about waveforms other than harmonic vibrations. This work presents SPICE simulations of piezoelectric micro energy harvester systems that differ in choice of power conditioning circuits and stopper models. We consider in detail both harmonic and random vibrations. The nonlinear switching conversion circuitry performs better than simple passive circuitry, especially when mechanical stoppers are in effect. Stopper loss is important under broadband vibrations. Stoppers limit the output power for sinusoidal excitations, but result in the same output power whether the stoppers are lossy or not. When the mechanical stoppers are hit by the proof mass during high-amplitude vibrations, nonlinear effects such as saturation and jumps are present. PMID:20378453

Blystad, Lars-Cyril; Halvorsen, Einar; Husa, Svein

2010-04-01

79

Efficiency Enhancement of a Cantilever-Based Vibration Energy Harvester  

PubMed Central

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 (Vave), 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).

Kubba, Ali E.; Jiang, Kyle

2014-01-01

80

Vibration energy absorption in the whole-body system of a tractor operator.  

PubMed

Many people are exposed to whole-body vibration (WBV) in their occupational lives, especially drivers of vehicles such as tractor and trucks. The main categories of effects from WBV are perception degraded comfort interference with activities-impaired health and occurrence of motion sickness. Absorbed power is defined as the power dissipated in a mechanical system as a result of an applied force. The vibration-induced injuries or disorders in a substructure of the human system are primarily associated with the vibration power absorption distributed in that substructure. The vibration power absorbed by the exposed body is a measure that combines both the vibration hazard and the biodynamic response of the body. The article presents measurement method for determining vibration power dissipated in the human whole body system called Vibration Energy Absorption (VEA). The vibration power is calculated from the real part of the force-velocity cross-spectrum. The absorbed power in the frequency domain can be obtained from the cross-spectrum of the force and velocity. In the context of the vibration energy transferred to a seated human body, the real component reflects the energy dissipated in the biological structure per unit of time, whereas the imaginary component reflects the energy stored/released by the system. The seated human is modeled as a series/parallel 4-DOF dynamic models. After introduction of the excitation, the response in particular segments of the model can be analyzed. As an example, the vibration power dissipated in an operator has been determined as a function of the agricultural combination operating speed 1.39 - 4.16 ms (-1) . PMID:24959797

Szczepaniak, Jan; Tana?, Wojciech; Kromulski, Jacek

2014-06-10

81

Energy Scavenging From Low-Frequency Vibrations by Using Frequency UpConversion for Wireless Sensor Applications  

Microsoft Academic Search

This paper presents an electromagnetic (EM) vibration-to-electrical power generator for wireless sensors, which can scavenge energy from low-frequency external vibrations. For most wireless applications, the ambient vibration is generally at very low frequencies (1-100 Hz), and traditional scavenging techniques cannot generate enough energy for proper operation. The reported generator up-converts low-frequency environmental vibrations to a higher frequency through a mechanical

Haluk Kulah; Khalil Najafi

2008-01-01

82

Vibrational energy relaxation in liquids  

NASA Astrophysics Data System (ADS)

The de-excitation of the vibrational population of small molecules in the liquid state is considered. Experimental techniques applicable to the measurement of relaxation times in dense phases are first described. Theoretical approaches are subsequently developed with special emphasis on the relationship between ab-initio quantum methods and binary interaction models. Finally, a selection of experimental results is analysed in the light of these theories. Special attention is given to the dependence of the relaxation time on experimental parameters such as density, temperature or the concentration of a mixture. The behaviour of the relaxation time across the liquid/solid phase transition is also treated. La désexcitation vibrationnelle de petites molécules est étudiée en phase liquide. Les techniques expérimentales utilisables pour mesurer les temps de relaxation en phase dense sont d'abord décrites. Les approches théoriques sont ensuite développées en montrant en particulier les liens entre les deux principales : l'approche quantique ab-initio et les modèles d'interaction binaire. Un choix de résultats expérimentaux est finalement analysé à la lumière de ces théories. Les dépendances des temps de relaxation envers les paramètres expérimentaux, comme la densité, la température ou la concentration d'un mélange, sont spécialement étudiées. Le comportement de la relaxation à la transition liquide/solide est aussi abordé.

Chesnoy, J.; Gale, G. M.

83

MARVEL: measured active rotational vibrational energy levels  

NASA Astrophysics Data System (ADS)

An algorithm is proposed, based principally on an earlier proposition of Flaud and co-workers [Mol. Phys. 32 (1976) 499], that inverts the information contained in uniquely assigned experimental rotational-vibrational transitions in order to obtain measured active rotational-vibrational energy levels (MARVEL). The procedure starts with collecting, critically evaluating, selecting, and compiling all available measured transitions, including assignments and uncertainties, into a single database. Then, spectroscopic networks (SN) are determined which contain all interconnecting rotational-vibrational energy levels supported by the grand database of the selected transitions. Adjustment of the uncertainties of the lines is performed next, with the help of a robust weighting strategy, until a self-consistent set of lines and uncertainties is achieved. Inversion of the transitions through a weighted least-squares-type procedure results in MARVEL energy levels and associated uncertainties. Local sensitivity coefficients could be computed for each energy level. The resulting set of MARVEL levels is called active as when new experimental measurements become available the same evaluation, adjustment, and inversion procedure should be repeated in order to obtain more dependable energy levels and uncertainties. MARVEL is tested on the example of the H 217O isotopologue of water and a list of 2736 dependable energy levels, based on 8369 transitions, has been obtained.

Furtenbacher, Tibor; Császár, Attila G.; Tennyson, Jonathan

2007-10-01

84

Feasibility study of multi-directional vibration energy harvesting with a frame harvester  

NASA Astrophysics Data System (ADS)

Vibration energy harvesting using piezoelectric material is a promising solution for powering small electric devices, which has attracted great research interest in recent years. Numerous efforts have been done by researchers to improve the efficiency of vibration energy harvesters and to broaden their bandwidths. In most reported literature, harvesters are designed to harvest energy from vibration source with a specific excitation direction. However, a practical environmental vibration source may include multiple components from different directions. Thus, it is an important concern to design a vibration energy harvester to be adaptive to multiple excitation directions. In this article, a novel piezoelectric energy harvester with frame configuration is proposed to address this issue. It can work either in its vertical vibration mode or horizontal vibration mode. Therefore, the harvester can capture vibration energy from arbitrary directions in a twodimensional plane. Experimental studies are carried out to prove the feasibility for multiple-direction energy harvesting using such harvester. The development of this two-dimensional energy harvester indicates its promising potential in practical vibration scenarios.

Wu, Hao; Tang, Lihua; Yang, Yaowen; Soh, Chee Kiong

2014-03-01

85

DESIGN CONSIDERATIONS FOR MEMS-SCALE PIEZOELECTRIC MECHANICAL VIBRATION ENERGY HARVESTERS  

Microsoft Academic Search

Design considerations for piezoelectric-based energy harvesters for MEMS-scale sensors are presented, including a review of past work. Harvested ambient vibration energy can satisfy power needs of advanced MEMS-scale autonomous sensors for numerous applications, e.g., structural health monitoring. Coupled 1-D and modal (beam structure) electromechanical models are presented to predict performance, especially power, from measured low-level ambient vibration sources. Models are

NOËL E. DUTOIT; BRIAN L. WARDLE; SANG-GOOK KIM

2005-01-01

86

PIEZOELECTRIC MICRO POWER GENERATOR FOR ENERGY HARVESTING  

Microsoft Academic Search

A thin film lead zirconate titanate Pb(Zr,Ti)O3 (PZT), power generating device is developed. It is designed to resonate at specific vibrational frequencies from an ambient, vibrational energy source, thereby creating electrical energy via the piezoelectric effect. The energy harvesting device uses the piezoelectric d33 mode and is fabricated with three mask steps. Our cantilever device was designed to have a

R. Sood; Y. B. Jeon; S. G. Kim

87

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

88

A vibration energy harvesting sensor platform for increased industrial efficiency  

NASA Astrophysics Data System (ADS)

A model for piezoelectric vibration energy harvesting with a piezoelectric cantilever beam is presented. The model incorporates expressions for variable geometry, tip mass, and material constants, and allows the parameterized determination of the voltage and power produced over a purely resistive load. The model is of a lumped-element form, with the base excitation acceleration and voltage representing the effort variables, and the tip velocity and electrical current representing the flow variables. Subsequent to the model's derivation, experimental results are presented and demonstrate the accuracy of the model. As peak power output for existing vibration configurations is typically of interest, several simple optimization studies are then performed on a simple generator configuration to demonstrate the effects of several of the driving geometric and material parameters.

Anderson, Todd A.; Sexton, Daniel W.

2006-04-01

89

Harvesting energy from the natural vibration of human walking.  

PubMed

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

90

Piezoelectric buckled beams for random vibration energy harvesting  

Microsoft Academic Search

Among the main vibration-to-electricity conversion systems, resonant harvesters suffer from a series of strong limits like their narrow frequency response and poor output power at small scale. Most of all, realistic vibration sources are variable in time and abundant at relatively low frequencies. Nonlinear vibration harvesters, on the other hand, are more attractive, thanks to their large bandwidth response and

F Cottone; L Gammaitoni; H Vocca; M Ferrari; V Ferrari

2012-01-01

91

Fundamental issues in nonlinear wideband-vibration energy harvesting  

NASA Astrophysics Data System (ADS)

Mechanically nonlinear energy harvesters driven by broadband vibrations modeled as white noise are investigated. We derive an upper bound on output power versus load resistance and show that, subject to mild restrictions that we make precise, the upper-bound performance can be obtained by a linear harvester with appropriate stiffness. Despite this, nonlinear harvesters can have implementation-related advantages. Based on the Kramers equation, we numerically obtain the output power at weak coupling for a selection of phenomenological elastic potentials and discuss their merits.

Halvorsen, Einar

2013-04-01

92

Fundamental issues in nonlinear wideband-vibration energy harvesting.  

PubMed

Mechanically nonlinear energy harvesters driven by broadband vibrations modeled as white noise are investigated. We derive an upper bound on output power versus load resistance and show that, subject to mild restrictions that we make precise, the upper-bound performance can be obtained by a linear harvester with appropriate stiffness. Despite this, nonlinear harvesters can have implementation-related advantages. Based on the Kramers equation, we numerically obtain the output power at weak coupling for a selection of phenomenological elastic potentials and discuss their merits. PMID:23679394

Halvorsen, Einar

2013-04-01

93

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

94

A Vibration Based Condition Monitoring System for Power Transformers  

Microsoft Academic Search

This paper is concerned with the design and development of an on-line condition monitoring system for large power transformers utilizing signals such as transformer vibration, voltages, currents, temperature and state of switches. The system consists of two parts which communicate each other via Ethernet or series port. The formal is a front-end computer subsystem used for data acquisition and processing,

He Ting-Ting; Wang Jing-Di; Guo Jie; Huang Hai; Chen Xiang-Xian; Pan Jie

2009-01-01

95

Optimization of partial constrained layer damping treatment for vibrational energy minimization of vibrating beams  

Microsoft Academic Search

An optimization study is presented in this paper with aim to minimize the vibrational energy (VE) of vibrating beams with passive constrained layer damping (PCLD) treatment. First, the governing equation of motion of a partially PCLD covered beam is derived on the basis of energy approach, and assumed-modes method is used to solve it. Parametric studies are then performed to

H. Zheng; C. Cai; X. M. Tan

2004-01-01

96

Resonant vibrational energy transfer in ice Ih.  

PubMed

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

97

Production, Delivery and Application of Vibration Energy in Healthcare  

NASA Astrophysics Data System (ADS)

In Rehabilitation Medicine therapeutic application of vibration energy in specific clinical treatments and in sport rehabilitation is being affirmed more and more.Vibration exposure can have positive or negative effects on the human body depending on the features and time of the characterizing wave. The human body is constantly subjected to different kinds of vibrations, inducing bones and muscles to actively modify their structure and metabolism in order to fulfill the required functions. Like every other machine, the body supports only certain vibration energy levels over which long term impairments can be recognized. As shown in literature anyway, short periods of vibration exposure and specific frequency values can determine positive adjustments.

Abundo, Paolo; Trombetta, Chiara; Foti, Calogero; Rosato, Nicola

2011-02-01

98

Vibration energy harvesting using a piezoelectric circular diaphragm array.  

PubMed

This paper presents a method for harvesting electric energy from mechanical vibration using a mechanically excited piezoelectric circular membrane array. The piezoelectric circular diaphragm array consists of four plates with series and parallel connection, and the electrical characteristics of the array are examined under dynamic conditions. With an optimal load resistor of 160 k?, an output power of 28 mW was generated from the array in series connection at 150 Hz under a prestress of 0.8 N and a vibration acceleration of 9.8 m/s(2), whereas a maximal output power of 27 mW can be obtained from the array in parallel connection through a resistive load of 11 k? under the same frequency, prestress, and acceleration conditions. The results show that using a piezoelectric circular diaphragm array can significantly increase the output of energy compared with the use of a single plate. By choosing an appropriate connection pattern (series or parallel connections) among the plates, the equivalent impedance of the energy harvesting devices can be tailored to meet the matched load of different applications for maximal power output. PMID:23007776

Wang, Wei; Yang, Tongqing; Chen, Xurui; Yao, Xi

2012-09-01

99

Vibration energy harvesting from random force and motion excitations  

Microsoft Academic Search

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

Xiudong Tang; Lei Zuo

2012-01-01

100

Power extraction using flow-induced vibration of a circular cylinder placed near another fixed cylinder  

NASA Astrophysics Data System (ADS)

We conducted an experiment in a towing tank to investigate the performance of an energy extraction system using the flow-induced vibration of a circular cylinder. This experiment tested three different cases involving the following arrangements of cylinder(s) of identical diameter: the upstream fixed-downstream movable arrangement (case F); the upstream movable-downstream fixed arrangement (case R); and a movable isolated cylinder (case I). In cases F and R, the separation distance (ratio of the distance between the centers of the two cylinders to their diameters) is fixed at 1.30. Measurement results show that while cases F and I generate vortex-induced vibration (VIV) resonance responses, case R yields wake-induced vibration (WIV) at reduced velocity over 9.0, which is significantly larger than that of the VIV response, leading to the induction of higher electronic power in a generator. Accordingly, primary energy conversion efficiency is higher in the case involving WIV.

Nishi, Yoshiki; Ueno, Yuta; Nishio, Masachika; Quadrante, Luis Antonio Rodrigues; Kokubun, Kentaroh

2014-05-01

101

Membrane-type vibrational energy harvester based on a multi-layered piezoelectric membrane  

NASA Astrophysics Data System (ADS)

In this study, we fabricated a membrane-type vibrational energy harvester by using a conventional micro-electro-mechanical (MEMS) method. The membrane-type vibrational energy harvester consists of a multi-layered diaphragm for stable and flexible vibration, a piezoelectric ZnO film for responding to the vibrational energy and for generating electric power, and a vibrator connected to the bottom of multi-layered diaphragm for enhancing the vibrational displacement of the diaphragm. First, we characterized the quality of a ZnO film through scanning electron microscopy (SEM), atomic force microscopy (AFM), and X-ray diffraction (XRD), which showed a preferred c-axis orientation, a hexagonal rod shape and a quite smooth surface. After the membrane-type vibrational energy harvester had been fabricated, we integrated it into a printing circuit board to realize piezoelectric generation and confirm its performance. Finally, under vibrational motion, we obtained a useful output voltage of 400 mV, and we estimated that the energy harvester generated an actual output voltage of about 200 uV.

Yoo, Seunghwan; Kim, Jonghun; Park, Suk-in; Jang, Cheol-Yong; Jeong, Hakgeun

2014-03-01

102

Experimental study of a self-powered and sensing MR-damper-based vibration control system  

NASA Astrophysics Data System (ADS)

The paper deals with a semi-active vibration control system based on a magnetorheological (MR) damper. The study outlines the model and the structure of the system, and describes its experimental investigation. The conceptual design of this system involves harvesting energy from structural vibrations using an energy extractor based on an electromagnetic transduction mechanism (Faraday's law). The system consists of an electromagnetic induction device (EMI) prototype and an MR damper of RD-1005 series manufactured by Lord Corporation. The energy extracted is applied to control the damping characteristics of the MR damper. The model of the system was used to prove that the proposed vibration control system is feasible. The system was realized in the semi-active control strategy with energy recovery and examined through experiments in the cases where the control coil of the MR damper was voltage-supplied directly from the EMI or voltage-supplied via the rectifier, or supplied with a current control system with two feedback loops. The external loop used the sky-hook algorithm whilst the internal loop used the algorithm switching the photorelay, at the output from the rectifier. Experimental results of the proposed vibration control system were compared with those obtained for the passive system (MR damper is off-state) and for the system with an external power source (conventional system) when the control coil of the MR damper was supplied by a DC power supply and analogue voltage amplifier or a DC power supply and a photorelay. It was demonstrated that the system is able to power-supply the MR damper and can adjust itself to structural vibrations. It was also found that, since the signal of induced voltage from the EMI agrees well with that of the relative velocity signal across the damper, the device can act as a 'velocity-sign' sensor.

Sapi?ski, Bogdan

2011-10-01

103

Novel piezoelectric bistable oscillator architecture for wideband vibration energy harvesting  

NASA Astrophysics Data System (ADS)

Bistable vibration energy harvesters are attracting more and more interest because of their capability to scavenge energy over a large frequency band. The bistable effect is usually based on magnetic interaction or buckled beams. This paper presents a novel architecture based on amplified piezoelectric structures. This buckled spring-mass architecture allows the energy of the dynamic mass to be converted into electrical energy in the piezoelectric materials as efficiently as possible. Modeling and design are performed and a normalized expression of the harvester behavior is given. Chirp and band-limited noise excitations are used to evaluate the proposed harvester’s performances. Simulation and experimental results are in good agreement. A method of using a spectrum plot for investigating the interwell motion is presented. The effect of the electric load impedance matching strategy is also studied. Results and comparisons with the literature show that the proposed device combines a large bandwidth and a high power density.

Liu, W. Q.; Badel, A.; Formosa, F.; Wu, Y. P.; Agbossou, A.

2013-03-01

104

A New Wideband Electromagnetic Vibration Energy Harvester with Chaotic Oscillation  

NASA Astrophysics Data System (ADS)

This paper presents a new electromagnetic vibration energy harvester (VEH) which harvests the electric power in wide frequency range. The present VEH contains the ferrite core embedded in the axis hole of the coil bobbin which generates the magnetic force acting on the oscillator. The performance of the present VEH is estimated using the coupled analysis method for VEH in which motion, Ampere, and circuit equations are alternatively solved until convergence. Using the coupled analysis method, the output power characteristic in the present VEH against input frequency is analyzed. It is shown from the analysis results that the present VEH has chaotic oscillation and wide frequency range for power generation. Moreover, the condition that the present VEH has nonlinear oscillation is discussed.

Sato, Takahiro; Igarashi, Hajime

2013-12-01

105

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

106

Adaptive piezoelectric energy harvesting circuit for wireless remote power supply  

Microsoft Academic Search

This paper describes an approach to harvesting electrical energy from a mechanically excited piezoelectric element. A vibrating piezoelectric device differs from a typical electrical power source in that it has a capacitive rather than inductive source impedance, and may be driven by mechanical vibrations of varying amplitude. An analytical expression for the optimal power flow from a rectified piezoelectric device

Geffrey K. Ottman; Heath F. Hofmann; Archin C. Bhatt; George A. Lesieutre

2002-01-01

107

Resonance tracking and vibration stablilization for high power ultrasonic transducers.  

PubMed

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

108

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

PubMed

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

109

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

PubMed Central

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%.

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

2014-01-01

110

Axial flow induced vibration of nuclear power plant components  

SciTech Connect

This work examines the vibrations, caused by axial turbulent flow, of long slender beam-like nuclear power plant components, such as tubes in a steam generator or fuel rods in a nuclear reactor, taking into account the hydrodynamic interaction among them. To accommodate probabilistic vibration analysis, the author developed a mathematical model for non-homogeneous cross spectral density of fluctuating wall-pressure caused by flow spoilers such as grid assembly in a reactor and support plate in a steam generator. The author has shown that the root-mean-square values of rod displacement calculated with this model agree well with measured values. A mathematical model has been developed to reduce the complexity in the vibration analysis of hydrodynamically coupled rod arrays. Based on this model, the author investigated the hydrodynamic coupling effect on the root mean square value of rod displacement which shows that ignoring the hydrodynamic coupling effect may not lead to a conservative prediction of rod displacement if driving forces on different rods are correlated with each other. Various axial model contributions to the vibration of multispanned steam generator tube have been investigated in terms of joint- and cross-acceptance. It is observed that higher mode contributions to the foot-mean-square displacement of tube and bending stress at tube ends are more significant than those in single-span tube in the low frequency region.

Baik, J.H.

1984-01-01

111

On the Effectiveness of Vibration-based Energy Harvesting  

Microsoft Academic Search

There has been a significant increase in the research on vibration-based energy harvesting in recent years. Most research is focused on a particular technology, and it is often difficult to compare widely differing designs and approaches to vibration-based energy harvesting. The aim of this study is to provide a general theory that can be used to compare different approaches and

Shad Roundy

2005-01-01

112

Vibrational energy transfer in shocked molecular crystals  

NASA Astrophysics Data System (ADS)

The vibrational energy transfer behind a shock and its possible role in the earliest stages of explosive initiation is considered. A new theory of multiphonon energy transfer into shocked molecules is developed which expands on existing treatments and allows consideration of a range of molecular crystals and liquids. Simple analytic forms are derived for the change in this energy transfer with increasing Hugoniot pressure or near simple defects. The time required for the total shocked system to come to thermal equilibrium is found to be an order of magnitude or more faster than proposed in previous work, in good agreement with recent molecular dynamics calculations. In typical energetic molecular crystals, thermal equilibration is predicted to occur two to five picoseconds following passage of the shock wave. Simple defects are introduced into the model by considering the mesoscale elastic strain fields surrounding an inhomogeneity. For straight dislocations, a region of modestly enhanced energy transfer on the scale of five nanometers is found. However, due to the rapid establishment of thermal equilibrium, we find it is unlikely these regions are related to hot spot formation. Indeed, the theory developed here suggests that the effect of nonequilibrium phonon processes on sensitivity or initiation is minimal.

Hooper, Joe

2009-06-01

113

A variable-capacitance vibration-to-electric energy harvester  

Microsoft Academic Search

Past research on vibration energy harvesting has focused primarily on the use of magnets or piezoelectric materials as the basis of energy transduction, with few experimental studies implementing variable-capacitance-based scavenging. In contrast, this paper presents the design and demonstration of a variable-capacitance vibration energy harvester that combines an asynchronous diode-based charge pump with an inductive energy flyback circuit to deliver

Bernard C. Yen; Jeffrey H. Lang

2006-01-01

114

A nanogenerator as a self-powered sensor for measuring the vibration spectrum of a drum membrane.  

PubMed

A nanogenerator (NG) is a device that converts vibration energy into electricity. Here, a flexible, small size and lightweight NG is successfully demonstrated as an active sensor for detecting the vibration spectrum of a drum membrane without the use of an external power source. The output current/voltage signal of the NG is a direct measure of the strain of the local vibrating drum membrane that contains rich informational content, such as, notably, the vibration frequency, vibration speed and vibration amplitude. In comparison to the laser vibrometer, which is excessively complex and expensive, this kind of small and low cost sensor based on an NG is also capable of detecting the local vibration frequency of a drum membrane accurately. A spatial arrangement of the NGs on the membrane can provide position-dependent vibration information on the surface. The measured frequency spectrum can be understood on the basis of the theoretically calculated vibration modes. This work expands the application of NGs and reveals the potential for developing sound wave detection, environmental/infrastructure monitoring and many more applications. PMID:23306794

Yu, Aifang; Zhao, Yong; Jiang, Peng; Wang, Zhong Lin

2013-02-01

115

Vibrational energy transfer in shocked molecular crystals.  

PubMed

We consider the process of establishing thermal equilibrium behind an ideal shock front in molecular crystals and its possible role in initiating chemical reaction at high shock pressures. A new theory of equilibration via multiphonon energy transfer is developed to treat the scattering of shock-induced phonons into internal molecular vibrations. Simple analytic forms are derived for the change in this energy transfer at different Hugoniot end states following shock compression. The total time required for thermal equilibration is found to be an order of magnitude or faster than proposed in previous work; in materials representative of explosive molecular crystals, equilibration is predicted to occur within a few picoseconds following the passage of an ideal shock wave. Recent molecular dynamics calculations are consistent with these time scales. The possibility of defect-induced temperature localization due purely to nonequilibrium phonon processes is studied by means of a simple model of the strain field around an inhomogeneity. The specific case of immobile straight dislocations is studied, and a region of enhanced energy transfer on the order of 5 nm is found. Due to the rapid establishment of thermal equilibrium, these regions are unrelated to the shock sensitivity of a material but may allow temperature localization at high shock pressures. Results also suggest that if any decomposition due to molecular collisions is occurring within the shock front itself, these collisions are not enhanced by any nonequilibrium thermal state. PMID:20078172

Hooper, Joe

2010-01-01

116

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

117

Electroelastic modeling and experimental validations of piezoelectric energy harvesting from broadband random vibrations of cantilevered bimorphs  

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

118

Energy Measurement of Bubble Bursting Based on Vibration Signals  

Microsoft Academic Search

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

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

2012-01-01

119

A role of solvent in vibrational energy relaxation of metalloporphyrins  

Microsoft Academic Search

The formation of a vibrationally excited photoproduct of metalloporphyrins upon (?, ?*) excitation and its subsequent vibrational energy relaxation were monitored by picosecond time-resolved resonance Raman spectroscopy. Stokes Raman bands due to a photoproduct of nickel octaethylporphyrin (NiOEP) instantaneously appeared upon the photoexcitation. Their intensities decayed with a time constant of ?300 ps, which indicates electronic relaxation from the (d,

Yasuhisa Mizutani; Teizo Kitagawa

2001-01-01

120

Electron energy distributions and vibrational population distributions.  

National Technical Information Service (NTIS)

This last year two experimental groups have reported on the vibrational population distributions of hydrogen molecules, H(sub 2)(v(double prime)), generated in a hydrogen discharge. These distributions extend up to the v(double prime) = 5 vibrational leve...

J. R. Hiskes

1989-01-01

121

Vibrational energy transfer in benzene-argon collisions  

SciTech Connect

This paper reports the results of an extensive study of the internal energy-transfer processes that occur in benzene-argon collisions. We used laser-induced fluorescence and information theory for determining the energy-transfer rates between internal states of benzene in the ground electronic state. The use of information theory gives estimates for all of the vibrational energy transfer rates. These fit the experimental data reasonably well. However, some of the data do deviate from the information theory model. This suggests that the statistical assumptions of the model are not sufficiently restrictive. One such restriction may be in the number of vibration quantum numbers that change in a collisional event. The rates of vibrational energy transfer depend strongly on the vibrational energy defect. 5 references, 8 figures, 3 tables.

Lyman, J.L.; Mueller, G.; Houston, P.L.; Piltch, M.; Schmid, W.E.; Kompa, K.L.

1985-01-01

122

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

123

Micro-scale piezoelectric vibration energy harvesting: From fixed-frequency to adaptable-frequency devices  

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 a priori, an adaptable-frequency energy harvester was designed. The adaptable-frequency harvester works by taking advantage of the coupling between

Miller, Lindsay Margaret

124

Vibrations  

NASA Astrophysics Data System (ADS)

Low frequent vibrations may cause from disturbing up to damaging effects. There is no precise distinction between structure-borne sound and vibrations. However - depending on the frequency range - measurements and predictions require different techniques. In a wide frequency range, the generation, transmission and propagation of vibrations can be investigated similar to structure-borne sound (see Chap. 9).

Guggenberger, Johannes; Müller, Gerhard

125

A wideband vibration energy harvester based on a folded asymmetric gapped cantilever  

NASA Astrophysics Data System (ADS)

This paper reports a wideband multi-mass multi-spring piezoelectric vibration energy harvester (VEH) based on a folded asymmetric gapped cantilever, which enables multiple resonant modes formed by pure bending of every stage. Moreover, the heaviest proof mass is placed at the last stage of the cantilever to increase the harvested power. The VEH's energy conversion efficiency is further increased using the asymmetric gapped structure. A prototype has been developed and characterized. The experimental results match with finite element simulation well. The prototype was tested on an air conditioning unit to demonstrate its energy harvesting capability with a realistic broadband vibration source.

Hu, Yating; Xu, Yong

2014-02-01

126

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

127

MEMS-Based Waste Vibrational Energy Harvesters.  

National Technical Information Service (NTIS)

The piezoelectric effect is a phenomenon where strain on a piezoelectric crystal structure causes potential difference at its ends. By merging piezoelectric materials and microelectromechanical systems (MEMS), mechanical vibration could cause the necessar...

D. B. Hogue S. M. Gregory

2013-01-01

128

Vibration energy harvesting using piezoelectric unimorph cantilevers with unequal piezoelectric and nonpiezoelectric lengths  

PubMed Central

We have examined a piezoelectric unimorph cantilever (PUC) with unequal piezoelectric and nonpiezoelectric lengths for vibration energy harvesting theoretically by extending the analysis of a PUC with equal piezoelectric and nonpiezoelectric lengths. The theoretical approach was validated by experiments. A case study showed that for a fixed vibration frequency, the maximum open-circuit induced voltage which was important for charge storage for later use occurred with a PUC that had a nonpiezoelectric-to-piezoelectric length ratio greater than unity, whereas the maximum power when the PUC was connected to a resistor for immediate power consumption occurred at a unity nonpiezoelectric-to-piezoelectric length ratio.

Gao, Xiaotong; Shih, Wei-Heng; Shih, Wan Y.

2010-01-01

129

Vibration energy harvesting using piezoelectric unimorph cantilevers with unequal piezoelectric and nonpiezoelectric lengths.  

PubMed

We have examined a piezoelectric unimorph cantilever (PUC) with unequal piezoelectric and nonpiezoelectric lengths for vibration energy harvesting theoretically by extending the analysis of a PUC with equal piezoelectric and nonpiezoelectric lengths. The theoretical approach was validated by experiments. A case study showed that for a fixed vibration frequency, the maximum open-circuit induced voltage which was important for charge storage for later use occurred with a PUC that had a nonpiezoelectric-to-piezoelectric length ratio greater than unity, whereas the maximum power when the PUC was connected to a resistor for immediate power consumption occurred at a unity nonpiezoelectric-to-piezoelectric length ratio. PMID:21200444

Gao, Xiaotong; Shih, Wei-Heng; Shih, Wan Y

2010-12-01

130

Vibration energy harvesting using piezoelectric unimorph cantilevers with unequal piezoelectric and nonpiezoelectric lengths  

NASA Astrophysics Data System (ADS)

We have examined a piezoelectric unimorph cantilever (PUC) with unequal piezoelectric and nonpiezoelectric lengths for vibration energy harvesting theoretically by extending the analysis of a PUC with equal piezoelectric and nonpiezoelectric lengths. The theoretical approach was validated by experiments. A case study showed that for a fixed vibration frequency, the maximum open-circuit induced voltage which was important for charge storage for later use occurred with a PUC that had a nonpiezoelectric-to-piezoelectric length ratio greater than unity, whereas the maximum power when the PUC was connected to a resistor for immediate power consumption occurred at a unity nonpiezoelectric-to-piezoelectric length ratio.

Gao, Xiaotong; Shih, Wei-Heng; Shih, Wan Y.

2010-12-01

131

Vibrational energy relaxation of water in Aerosol OT reverse micelle  

NASA Astrophysics Data System (ADS)

An IR-Raman technique with mid-IR pump and anti-Stokes Raman probe is used to investigate reverse micelle mixture of Aerosol OT, water, and carbon tetrachloride, where polar water phase and nonpolar oil phase is separated by a monolayer of surfactant molecules. Anti-Stokes Raman scattering is only dependent on the population of vibrationally excited states, thus time-dependent population changes of parent/daughter vibrations can be monitored with this technique. Vibrational energy from nanodroplet of water is transferred to the surfactant head group in 1.8 ps and then out to solvent in 10 ps. Vibrational energy directly pumped into the surfactant tail group results in a slower 20-40 ps energy transfer to solvent. This energy transfer cannot be explained by ordinary heat transfer, but the specific vibrational energy relaxation pathway such as sulfonate stretch of surfactant molecules should be used. We can change the water-to-solvent energy transfer rate by adopting different size of reverse micelles or changing pump frequency over the broad OH stretch mode of water due to hydrogen bond network. Water molecules confined in nanometer scale reverse micelles have very different properties from bulk water and we have found many differences between the vibrational dynamics of water in these reverse micelles and those of bulk water.

Pang, Yoonsoo; Deak, John; Dlott, Dana

2005-03-01

132

A two-mass cantilever beam model for vibration energy harvesting applications  

Microsoft Academic Search

While vibration energy harvesting has become a viable means to power wireless sensors, narrow bandwidth is still a hurdle to the practical use of the technology. For conventional piezoelectric or electromagnetic harvesters, having multiple proof masses mounted on a beam is one way to widen the effective bandwidth. This is because the addition of proof masses increases the number of

Qing Ou; XiaoQi Chen; Stefanie Gutschmidt; Alan Wood; Nigel Leigh

2010-01-01

133

Electromagnetic energy harvester with repulsively stacked multilayer magnets for low frequency vibrations  

NASA Astrophysics Data System (ADS)

This paper investigates the applicability of an electromagnetic generator with repulsively stacked magnets for harvesting energy from traffic-induced bridge vibrations. First, the governing equation for electro-mechanical coupling is presented. The magnetic field for repulsive pole arrangements is discussed and the model is validated from a magnet falling test. The detailed design, fabrication, and test results of a prototype device are presented in the paper. An experimental vibration shaker test is conducted to assess the performance of the energy harvester. Field test and numerical simulation at the 3rd Nongro Bridge in South Korea shows that the device can generate an average power of 0.12 mW from an input rms acceleration of 0.25 m s-2 at 4.10 Hz. With further frequency tuning and design improvement, an average power of 0.98 mW could be potentially harvested from the ambient vibration of the bridge.

Kwon, Soon-Duck; Park, Jinkyoo; Law, Kincho

2013-05-01

134

Non-Linear Vibration of Power Transmission Belts  

NASA Astrophysics Data System (ADS)

Non-linear vibration of a prototypical power transmission belt system, which is excited by pulleys having slight eccentricity, is investigated through experimental and analytical methods. Laboratory measurements demonstrate the role of non-linearity in setting the belt's response, particularly in the near-resonance region, and at high running speeds. The belt is coated with a retroreflective medium so as to improve displacement and velocity measurements made through non-contact laser interferometry. A frequency crossing diagram relates the belt's speed-dependent excitation and natural frequencies, and is shown to be useful for identifying those speeds at which resonance is expected. Distinctive jump and hysteresis phenomena in the near-resonant response are observed experimentally, and are also studied with a model that includes non-linear stretching of the belt. In that regard, a modal perturbation solution is developed in the context of the asymptotic method of Krylov, Bogoliubov and Mitropolsky for a general, continuous, non-autonomous, gyroscopic system with weakly non-linear stiffness. The solution is subsequently specialized to the belt vibration problem at hand. Near- and exact-resonant response amplitudes are predicted by the perturbation method, and they are compared with those obtained by laboratory tests and by direct numerical simulation of the non-linear model.

Moon, J.; Wickert, J. A.

1997-03-01

135

Vibration  

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

136

Energy-based comparison of various controllers for vibration suppression using piezoceramics  

NASA Astrophysics Data System (ADS)

The large-scale and light-weight design trend in aircraft and spacecraft results in extremely flexible structures with lowfrequency vibration modes. Suppression of undesired vibrations in such flexible structures with limited energy is becoming an important design problem to develop energy-autonomous controllers powered using the harvested ambient energy. The objective of this paper is to compare different control laws to suppress low-frequency vibrations using the minimum actuation energy for the same system and under the same design constraint (identical settling time for free vibrations). The vibration suppression performance of four active control systems as well as their hybrid versions employing a switching technique are presented and compared. The control systems compared here are a Positive Position Feedback (PPF) controller, a Proportional Integral Derivative (PID) controller, a nonlinear controller (with a second-order nonlinear term multiplying the position and velocity feedback to create variable damping), a Linear Quadratic Regulator (LQR) controller and their hybrid versions integrating a bang-bang control law (on-off control) with each of these controllers. Experimental results are presented for a thin cantilevered beam with a piezoceramic transducer controlled by these eight controllers with a focus on the fundamental vibration mode under transverse free vibrations and the control energy requirements are compared. Experiments results reveal that all the controllers reduce the vibration settling time to 0.85s as a design constraint (which is 92.3% of the open-loop settling time: 10.9s). The average actuation power input provided to the piezoceramic transducer in each case is obtained for the time current and voltage measurements until the settling time. Comparisons show that the switching technology reduces significant actuation power requirement, so that all the hybrid control systems require much less power than their conventional versions. Especially, the hybrid bang-bang-nonlinear controller requires 67% less power than the conventional nonlinear controller. In order to verify this statement, the actuation current is theoretically calculated through piezo-capacitance using voltage measurements to check out the average power estimation. The theoretical checking out provides the same results with slightly error, which can be explained by measurement errors.

Wang, Ya; Inman, Daniel J.

2011-03-01

137

Vibrational spectroscopy of HOD in liquid D2O. VI. Intramolecular and intermolecular vibrational energy flow  

NASA Astrophysics Data System (ADS)

In a previous theoretical study [J. Chem. Phys. 117, 5827 (2002)] we calculated the vibrational lifetimes of the three fundamentals of HOD in liquid D2O. In that calculation the D2O solvent was treated as rigid, not allowing for the possibility of intermolecular vibrational energy transfer as a relaxation mechanism. In this paper we use both flexible and rigid solvent models, enabling us to include the possibility of intermolecular vibrational energy transfer, and also to estimate branching ratios for vibrational and nonvibrational relaxation channels. Our theoretical value for the lifetime of the OH stretch decreases modestly from 2.7 ps (in the original calculation) to 2.3 ps, which should be compared to the experimental value of about 1 ps. The lifetime of the OD stretch decreases dramatically from 18 ps to 390 fs due to resonant energy transfer to the solvent stretch. Our lifetime value for the bend actually increases from 220 to 380 fs, not because of the vibrational energy transfer channel, but rather because we find that Fermi's Golden Rule (used in the original calculation) breaks down for this very fast process. We have calculated all the state-to-state rate constants for the low-lying vibrational energy levels of HOD, which allows us to construct and solve the vibrational master equation. We find that after excitation of the OH stretch, population flows into the HOD bend states (and to a lesser extent the OD stretch of HOD) on the time scale of 1 ps, in agreement with recent infrared pump/Raman probe measurements of Dlott and co-workers. From our results we estimate that for each quantum of OH stretch excitation, 0.26 quanta of solvent stretch is excited by direct intermolecular energy transfer, and yet we find, surprisingly, that there is almost no direct excitation of solvent bend. On the other hand, we suggest that because of the intramolecular Fermi resonance in D2O, rapid intramolecular vibrational relaxation occurs from solvent stretch to solvent bend. This would account for the experimental observation of solvent stretch and bend excitations on the time scale of 1 ps after the OH stretch is excited.

Lawrence, C. P.; Skinner, J. L.

2003-07-01

138

Buck-boost converter for simultaneous semi-active vibration control and energy harvesting for electromagnetic regenerative shock absorber  

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

139

Application of the energy balance method to nonlinear vibrating equations  

Microsoft Academic Search

In this paper, He’s energy balance method is applied to nonlinear vibrations and oscillations. The method is applied to four nonlinear differential equations. It has indicated that by utilizing He’s energy balance method (HEBM), just one iteration leads us to high accuracy of solutions. It has illustrated that the energy balance methodology is very effective and convenient and does not

I. Mehdipour; D. D. Ganji; M. Mozaffari

2010-01-01

140

Development and testing of a dynamic absorber with corrugated piezoelectric spring for vibration control and energy harvesting applications  

NASA Astrophysics Data System (ADS)

Vibrational energy harvesting devices are often designed in a manner analogous to classical dynamic vibration absorbers (DVAs). An electromechanical mass-spring system is devised so as to resonate at the frequency most dominant in the environmental vibration spectrum; the consequent device oscillation is converted to a electrical signal which is harnessed for immediate usage or as a charging mechanism for a battery. The DVA is likewise designed but with the intention of inducing substantial inertial influence upon a host structure for vibration control purposes, either to globally dampen the vibration of the main body or, in an undamped configuration to "absorb" the primary system vibration at a single frequency. This paper describes the development of an electromechanical mass-spring-damper which seeks to serve both goals of passive vibration control and energy harvesting. The device utilizes a piezoelectric film spring and a distributed mass layer so as to be suitable for the attenuation of surface vibrations and to convert a portion of the absorbed energy into electric power. The development and design of the device are presented and the results of realistic tests are provided to show both the potentials and the challenges encountered when attempting to superpose the goals of vibration control and energy harvesting.

Harne, R. L.

2013-04-01

141

EXPERIMENTAL STUDY ON CONTROL PARAMETERS FOR AERODYNAMIC VIBRATION-BASED POWER GENERATION USING FEEDBACK AMPLIFICATION  

NASA Astrophysics Data System (ADS)

In order to develop a new wind power generation method using feedback amplification of the windinduced vibration caused between two tandem circular cylinders, wind tunnel experiments were conducted. The effects of two feedback control parameters on the vibrational property were investigated through the experiments. The maximum vibration amplitude is ob tained when the upstream cylinder is vibrated with the time lag corresponding to 80% of the characteristic period of the downstream cylinder, and prescribed by the control gain independently of the wind speed. Although the vibration amplitude is enhanced in proportion to the control gain, this enhancement diminishes beyond a critical gain.

Hiejima, Shinji; Nakano, Seishiro

142

Vibration-translation energy transfer in vibrationally excited diatomic molecules. Ph.D. Thesis - York Univ., Toronto  

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

143

Vibrational energy transfer in diatom-triatom collisions  

Microsoft Academic Search

A quantum-dynamical method is described for calculating exact vibrational transition probabilities for the fixed angle scattering of a diatomic molecule with a linear triatomic molecule. The method can be used for any realistic diatom-triatom potential energy surface. Application of the technique is made to the collisions of N2(u) with CO2(v1v2), where u is the vibrational quantum number of N2 and

D. C. Clary

1981-01-01

144

Investigation of concurrent energy harvesting from ambient vibrations and wind using a single piezoelectric generator  

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

145

IEEE Power and Energy  

NSDL National Science Digital Library

IIEEE presents Power and Energy magazine online. The latest issue as well as several previous issues are available online for free use. Columns of Power and Energy highlight history, industry news, standards, and opinion articles. The archives currently go back to 2009.

2003-01-01

146

Chemical reaction versus vibrational quenching in low energy collisions of vibrationally excited OH with O  

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

147

Chemical reaction versus vibrational quenching in low energy collisions of vibrationally excited OH with O  

SciTech Connect

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

148

Spectroscopic probes of vibrationally excited molecules at chemically significant energies  

SciTech Connect

These experiments apply multiple-laser spectroscopic techniques to investigate the bond energies, potential surface topologies, and dissociation dynamics of highly vibrationally excited molecules. Infrared-optical double resonance pumping of light atom stretch vibrations in H{sub 2}O{sub 2} and HN{sub 3} prepares reactant molecules in single rovibrational states above the unimolecular dissociation threshold on the ground potential surface, and laser induced fluorescence detection of the OH or NH fragments monitors the partitioning of energy into individual product quantum states. Product energy partitioning data from H{sub 2}O{sub 2} dissociation provide a stringent test of statistical theories as well as potential energy surface calculations. Ongoing work on HN{sub 3} seeks to determine the height of the barrier to dissociation on the singlet potential energy surface. Our most recently developed spectroscopic scheme allows the measurement of high vibrational overtone spectra of jet-cooled molecules. This approach uses CO{sub 2} laser infrared multiphoton dissociation followed by laser induced fluorescence product detection to measure weak vibrational overtone transitions in low pressure environments. Application of this scheme to record the {Delta}V{sub OH}=4 and {Delta}V{sub OH}=5 transitions of CH{sub 3}OH cooled in a supersonic free-jet demonstrates both its feasibility and its utility for simplifying high vibrational overtone spectra.

Rizzo, T.R.

1992-03-01

149

Apparent Mass and Absorbed Power during Exposure to Whole-Body Vibration and Repeated Shocks  

NASA Astrophysics Data System (ADS)

Exposure to mechanical shocks might pose a greater health risk than exposure to continuous vibration. Previous studies have investigated subjective responses, muscle activity or transmission of vibration to the spine or head during shock. If there is a difference between biomechanic responses of the seated body to shocks when compared to continuous vibration, then this may indicate a more, or less, hazardous vibration waveform. This paper presents measurements of apparent mass and absorbed power during exposure to random vibration, repeated shocks and combinations of shocks and random vibration. Eleven male and 13 female subjects were exposed to 15 vibration conditions generated using an electro-dynamic shaker. Subjects were exposed to five 20 s acceleration waveforms with nominally identical power spectra (random vibration, equally spaced shocks, unequally spaced shocks, random combined with equally spaced shocks, random combined with unequally spaced shocks) at each of 0·5, 1·0 and 1·5 m/s2r.m.s. The general shapes of the apparent mass or absorbed power curves were not affected by stimulus type, indicating that the biomechanical response of the body is fundamentally the same when exposed to shocks or random vibration. Two non-linear effects were observed: apparent mass resonance frequencies were slightly higher for exposure to shocks; apparent mass and absorbed power resonance frequencies decreased with increases in vibration magnitude for each stimulus type. It is concluded that the two non-linear mechanisms operate simultaneously: a stiffening effect during exposure to shocks and a softening effect as vibration magnitudes increase. Total absorbed powers were greatest for shock stimuli and least for random vibration.

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

2001-11-01

150

Optimization design of high power ultrasonic circular ring radiator in coupled vibration.  

PubMed

This paper presents a new high power ultrasonic (HPU) radiator, which consists of a transducer, an ultrasonic horn, and a metal circular ring. Both the transducer and horn in longitudinal vibrations are used to drive a metal circular ring in a radial-axial coupled vibration. This coupled vibration cannot only generate ultrasound in both the radial and axial directions, but also focus the ultrasound inside the circular ring. Except for the radial-axial coupled vibration mode, the third longitudinal harmonic vibration mode with relative large vibration amplitude is also detected, which can be used as another operation mode. Overall, the HPU with these two vibration modes should have good potential to be applied in liquid processing, such as sonochemistry, ultrasonic cleaning, and Chinese herbal medicine extraction. PMID:21529873

Xu, Long; Lin, Shuyu; Hu, Wenxu

2011-10-01

151

Dynamics and power flow behaviour of a nonlinear vibration isolation system with a negative stiffness mechanism  

NASA Astrophysics Data System (ADS)

The dynamics and power flow behaviour of a nonlinear vibration isolation system with a negative stiffness mechanism (NSM) are studied. The mathematical equations governing the nonlinear dynamics of the system are derived. The averaging method is used to obtain the frequency response function of the system subject to harmonic excitations. It is found that adding NSM can greatly enlarge the frequency band for effective vibration isolation. Numerical simulations reveal that sub-harmonic resonance may occur even when the excitation frequency is well above the natural frequency of the linearized system. As the effects of sub-harmonic response cannot be reflected by the averaging formulations, numerical integrations are used to obtain the dynamic responses including sub-harmonic and other frequency components. Furthermore, power flow characteristics of this nonlinear isolation system are examined for a better assessment of the isolation performance. The results show that the occurrences of sub-harmonic resonance may considerably increase both the time-averaged input power and the maximum kinetic energy. Compared with linear systems, the power flows of the nonlinear system might be non-unique and sensitive to the initial conditions. Some suggestions on restricting the maximum deflection and suppressing sub-harmonic resonances are provided for effective designs of nonlinear isolation systems.

Yang, J.; Xiong, Y. P.; Xing, J. T.

2013-01-01

152

Analytical and experimental comparisons of electromechanical vibration response of a piezoelectric bimorph beam for power harvesting  

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

153

Tapered piezoelectric devices for vibration energy harvesting  

NASA Astrophysics Data System (ADS)

The use of cantilevered piezoelectric bimorphs under transversal excitations is an area of research well reported in literature. These devices may be tapered into triangular geometries in order to enhance axial strain over the surfaces of the device for more reliable operation. This study reports the comparison of rectangular and triangular cantilevered bimorphs of equal volume and matching resonance frequency, where it is seen that tapering geometry enhances the electromechanical coupling coefficient, which may not necessarily be the only parameter involved in enhancing power output. This is indicated in the case of a triangular cantilevered device without a proof mass, which with increased coupling is unable to outperform a rectangular device. The addition of a nominal proof mass on a rectangular and triangular device increases not only the electromechanical coupling coefficient, but also increases the damping ratio in the devices. This effect is more pronounced in the case of triangular bimorphs, and a 40% improvement in power output is seen. Therefore, these studies provides insights into the changing parameters with changing shapes, which may provide better optimization parameters for improving piezoelectric energy harvesting from cantilevered devices.

Siddiqui, Naved A.; Roberts, Matthew I.; Kim, Dong-Joo; Overfelt, Ruel A.; Prorok, Barton C.

2014-03-01

154

MEMS-based thick film PZT vibrational energy harvester  

Microsoft Academic Search

We present a MEMS-based unimorph silicon\\/PZT thick film vibrational energy harvester with an integrated proof mass. We have developed a process that allows fabrication of high performance silicon based energy harvesters with a yield higher than 90%. The process comprises a KOH etch using a mechanical front side protection of an SOI wafer with screen printed PZT thick film. The

A. Lei; R. Xu; A. Thyssen; A. C. Stoot; T. L. Christiansen; K. Hansen; R. Lou-Moller; E. V. Thomsen; K. Birkelund

2011-01-01

155

Development of a Cantilever Beam Generator Employing Vibration Energy Harvesting  

Microsoft Academic Search

This paper details the development of a generator based upon a cantilever beam inertial mass system which harvests energy from ambient environmental vibrations. The paper compares the predicted results from Finite Element Analysis (FEA) of the mechanical behaviour and magnetic field simulations and experimental results from a generator. Several design changes were implemented to maximise the conversion of magnetic energy

R. N. Torah; S. P. Beeby; M. J. Tudor; T. O'Donnell; S. Roy

156

Energy harvesting of radio frequency and vibration energy to enable wireless sensor monitoring of civil infrastructure  

NASA Astrophysics Data System (ADS)

To power distributed wireless sensor networks on bridges, traditional power cables or battery replacement are excessively expensive or infeasible. This project develops two power harvesting technologies. First, a novel parametric frequency-increased generator (PFIG) is developed. The fabricated PFIG harvests the non-periodic and unprecedentedly low frequency (DC to 30 Hz) and low acceleration (0.55-9.8 m/s2) mechanical energy available on bridges with an average power > 2 ?W. Prototype power conversion and storage electronics were designed and the harvester system was used to charge a capacitor from arbitrary bridge-like vibrations. Second, an RF scavenger operating at medium and shortwave frequencies has been designed and tested. Power scavenging at MHz frequencies allows for lower antenna directivities, reducing sensitivity to antenna positioning. Furthermore, ambient RF signals at these frequencies have higher power levels away from cities and residential areas compared to the UHF and SHF bands utilized for cellular communication systems. An RF power scavenger operating at 1 MHz along with power management and storage circuitry has been demonstrated. It powers a LED at a distance of 10 km from AM radio stations.

Galchev, Tzeno; McCullagh, James; Peterson, Rebecca L.; Najafi, Khalil; Mortazawi, Amir

2011-03-01

157

Dynamics of vibrating systems with tuned liquid column dampers and limited power supply  

NASA Astrophysics Data System (ADS)

Tuned liquid column dampers are U-tubes filled with some liquid, acting as an active vibration damper in structures of engineering interest like buildings and bridges. We study the effect of a tuned liquid column damper in a vibrating system consisting of a cart which vibrates under driving by a source with limited power supply (non-ideal excitation). The effect of a liquid damper is studied in some dynamical regimes characterized by coexistence of both periodic and chaotic motion.

de Souza, S. L. T.; Caldas, I. L.; Viana, R. L.; Balthazar, J. M.; Brasil, R. M. L. R. F.

2006-02-01

158

Vibrational analysis of power tools using a novel three-dimensional scanning vibrometer  

NASA Astrophysics Data System (ADS)

Scanning Laser Doppler Vibrometers (SLDV) are widely used in product development. Power tools as for example percussion drilling machines are known to be noisy and vibrating. It is state of the art to reduce the noise and vibration by finding the sources therefrom with LDV. Although these data give important information about the vibrational behavior, for a deeper understanding three dimensional vibration data is required. Therefore, for the first time measurements on power tools have been performed using a novel 3D SLDV, which simultaneously measures three components of the vibration vectors using three vibrometers. Power tools are observed under operating conditions close to reality, operated by a human. As the device under test performs movements in all directions, the three laser beams do not perfectly intersect. It is shown, that the introduced error can be neglected for low frequencies. Results are presented for a percussion drilling machine and a random orbit sander.

Bendel, Karl; Fischer, Martin; Schuessler, Matthias

2004-06-01

159

Experimental study of a self-powered and sensing MR-damper-based vibration control system  

Microsoft Academic Search

The paper deals with a semi-active vibration control system based on a magnetorheological (MR) damper. The study outlines the model and the structure of the system, and describes its experimental investigation. The conceptual design of this system involves harvesting energy from structural vibrations using an energy extractor based on an electromagnetic transduction mechanism (Faraday's law). The system consists of an

Bogdan Sapinski

2011-01-01

160

Power wind mill fault detection via one-class ?-SVM vibration signal analysis  

Microsoft Academic Search

Vibration analysis is one of the most used tech- niques for predictive maintenance in high-speed rotating ma- chinery. Using the information contained in the vibration signals, a system for alarm detection and diagnosis of failures in mechanical components of power wind mills is devised. As previous failure data collection is unfeasible in real life scenarios, the method to be employed

David Martinez-Rego; Oscar Fontenla-Romero; Amparo Alonso-Betanzos

2011-01-01

161

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

162

Vibration characterisation of cymbal transducers for power ultrasonic applications  

NASA Astrophysics Data System (ADS)

A Class V cymbal flextensional transducer is composed of a piezoceramic disc or ring sandwiched between two cymbal-shaped shell end-caps. These end-caps act as mechanical transformers to convert high impedance, low radial displacement of the piezoceramic into low impedance, large axial motion of the end-cap. The cymbal transducer was developed in the early 1990's at Penn State University, and is an improvement of the moonie transducer which has been in use since the 1980's. Despite the fact that cymbal transducers have been used in many fields, both as sensors and actuators, due to its physical limitations its use has been mainly at low power intensities. It is only very recently that its suitability for high amplitude and high power applications has been studied, and consequently implementation in this area of research remains undeveloped. This paper employs experimental modal analysis (EMA), vibration response measurements and electrical impedance measurements to characterise two variations of the cymbal transducer design, both aimed at incorporation in ultrasonic cutting devices. The transducers are fabricated using the commercial Eccobond 45LV epoxy adhesive as the bonding agent. The first cymbal transducer is of the classic design where the piezoceramic disc is bonded directly to the end-caps. The second cymbal transducer includes a metal ring bonded to the outer edge of the piezoceramic disc. The reason for the inclusion of this metal ring is to improve the mechanical coupling with the end-caps. This would therefore make this design particularly suitable for power ultrasonic applications, reducing the possibility of debonding at the higher ultrasonic amplitudes. The experimental results demonstrate that the second cymbal design is a significant improvement on the more classic design, allowing the transducer to operate at higher voltages and higher amplitudes, exhibiting a linear response over a practical power ultrasonic device driving voltage range. The results also show that the device can be accurately tuned using finite element modelling and that the cymbal exhibits a modal response as predicted by the finite element models.

Bejarano, F.; Feeney, A.; Lucas, M.

2012-08-01

163

Intramolecular Vibrational Energy Redistribution in the Reaction H_{3}^{+} + CO --> H_2 + HCO^+\\/HOC^+  

Microsoft Academic Search

Observations of the rotational lines of HCO^+ produced in an extended negative glow discharge revealed high vibrational temperatures for the stretching vibrational modes, and non-thermal population distributions among the different l levels of excited bending vibrational states. These results provide critical tests of our understanding of the dynamics and intramolecular vibrational energy redistribution (IVR) in this reaction process. The IVR

Tsuneo Hirano; Hui Li; Robert J. Le Roy; Takayoshi Amano

2009-01-01

164

Minimization of the vibration energy of thin-plate structures and the application to the reduction of gearbox vibration  

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

165

Harvested power and sensitivity analysis of vibrating shoe-mounted piezoelectric cantilevers  

NASA Astrophysics Data System (ADS)

This paper presents a preliminary investigation on energy harvesting from human walking via piezoelectric vibrating cantilevers. Heel accelerations during human gait are established by correlating data gathered from the literature with direct experimental measurements. All the observed relevant features are synthesized in a typical (standard) acceleration signal, used in subsequent numerical simulations. The transient electromechanical response and the harvested power of a shoe-mounted bimorph cantilever excited by the standard acceleration signal is computed by numerical simulations and compared with measurements on a real prototype. A sensitivity analysis is finally developed to estimate the mean harvested power for a wide range of scavenger configurations. Acceptability criteria based on imposed geometrical constraints and resistance strength limits (e.g. fatigue limit) are also established. This analysis allows a quick preliminary screening of harvesting performance of different scavenger configurations.

Moro, L.; Benasciutti, D.

2010-11-01

166

On Mechanical Modeling of Cantilevered Piezoelectric Vibration Energy Harvesters  

Microsoft Academic Search

Cantilevered beams with piezoceramic (PZT) layers are the most commonly investigated type of vibration energy harvesters. A frequently used modeling approach is the single-degree-of-freedom (SDOF) modeling of the harvester beam as it allows simple expressions for the electrical outputs. In the literature, since the base excitation on the harvester beam is assumed to be harmonic, the well known SDOF relation

A. Erturk; D. J. Inman

2008-01-01

167

Magnetoelectric Energy Harvesting from Vibrations of Multiple Frequencies  

Microsoft Academic Search

A novel multi-frequency vibration energy harvester has been designed and fabricated, which consists of two cantilever beams, two magnetoelectric (ME) transducers and a magnetic circuit. In the harvester, the magnetic forces between the ME transducers and the magnetic circuit will result in additional magnetic stiffness on the two cantilever beams, on which the frequency response of the harvester is highly

Jin Yang; Yumei Wen; Ping Li

2011-01-01

168

Experimental Vibrational Zero-Point Energies: Diatomic Molecules  

Microsoft Academic Search

Vibrational zero-point energies (ZPEs), as determined from published spectroscopic constants, are derived for 85 diatomic molecules. Standard uncertainties are also provided, including estimated contributions from bias as well as the statistical uncertainties propagated from those reported in the spectroscopy literature. This compilation will be helpful for validating theoretical procedures for predicting ZPEs, which is a necessary step in the ab

Karl K. Irikura

2007-01-01

169

Modelling of a Bi-axial Vibration Energy Harvester.  

National Technical Information Service (NTIS)

This report fully details the techniques involved in the modelling of a nonlinear and bi-axial vibration energy harvesting device. The device utilises a wire-coil electromagnetic (EM) transducer within a nonlinear oscillator created with a permanent-magne...

L. A. Vandewater S. D. Moss

2013-01-01

170

Electromagnetic Vibration Energy Harvester Using Springless Proof Mass and Ferrofluid as a Lubricant  

NASA Astrophysics Data System (ADS)

This paper presents an electromagnetic energy harvester using an array of rectangular permanent magnets as springless proof mass and ferrofluid as a lubricating material. Lateral motion of the multi-pole magnet array generates voltage across an array of copper windings formed under the aluminum channel in response to low frequency external vibrations such as human-body-induced motion. A proof-of-concept device has been fabricated and output voltage has been measured at various input frequencies and accelerations provided by a vibration exciter. Device with ferrofluid lubrication generated maximum open-circuit voltage of 0.47V at 3g vibration at 12Hz, which is 8% higher than that of the device without lubricant. Maximum output power of 71.26?W has been obtained at 40.8? with the device with ferrofluid lubrication.

Chae, S. H.; Ju, S.; Choi, Y.; Jun, S.; Park, S. M.; Lee, S.; Lee, H. W.; Ji, C.-H.

2013-12-01

171

Radioisotope Power Generator (RPG) Sentinel 25F Shock and Vibration Studies.  

National Technical Information Service (NTIS)

An investigation was conducted to determine the ruggedness and performance of a commercially designed Radioisotope Power Generator, Sentinel 25, under varying conditions of shock and vibration. A test program was designed incorporating the basic design co...

E. M. Rzepka

1974-01-01

172

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

173

Ultrafast vibrational dynamics and energy transfer in imidazolium ionic liquids.  

PubMed

Femtosecond time-resolved coherent anti-Stokes Raman scattering (CARS) is used as a probe for monitoring the vibrational dynamics of room temperature ionic liquids (ILs). The experiments are performed on a series of 1,3-dialkylimidazolium ILs containing the bis(trifluoromethylsulfonyl)imide [NTf2] anion. The effect of methylation of the cationic C2 position on the dephasing time is studied analyzing [NTf2]-ILs of 1-ethyl-3-methylimidazolium [EMIM], 1-ethyl-2,3-dimethylimidazolium [EMMIM], 1-butyl-3-methylimidazolium [BMIM], and 1-butyl-2,3-dimethylimidazolium [BMMIM]. Raman coherences are excited around ?1400 cm(-1), and the vibrational dephasing of the modes in the fingerprint region is monitored as a function of time. The results indicate that vibrational energy transfer occurs governed by the interionic interactions. This is suggested by mode beating involving vibrations beyond the excitation spectrum as well as systematic differences in the temporal dephasing behavior. In contrast, the length of the cationic alkyl side chain has a negligible impact on the vibrational dynamics. PMID:24697246

Namboodiri, Mahesh; Kazemi, Mehdi Mohammad; Zeb Khan, Tahir; Materny, Arnulf; Kiefer, Johannes

2014-04-23

174

Efficient Energy Harvesting from Irregular Mechanical Vibrations by Active Motion Control  

Microsoft Academic Search

A vibration-driven micropower generator with a high-Q mechanical resonator efficiently works under single-frequency vibration. However, the associated narrow operation frequency bandwidth tightly limits the power output under commonly observed wideband ambient vibrations. In this paper, we present a power-generation scheme in which the motion of an internal mass element is actively controlled. The control is such that the vibrating environment

Hiroshi Okamoto; Teppei Onuki; Sumito Nagasawa; Hiroki Kuwano

2009-01-01

175

Vibrational zero point energy for H-doped silicon  

NASA Astrophysics Data System (ADS)

Most of the studies addressed to computations of hydrogen parameters in semiconductor systems, such as silicon, are performed at zero temperature T = 0 K and do not account for contribution of vibrational zero point energy (ZPE). For light weight atoms such as hydrogen (H), however, magnitude of this parameter might be not negligible. This Letter is devoted to clarify the importance of accounting the zero-point vibrations when analyzing hydrogen behavior in silicon and its effect on silicon electronic properties. For this, we estimate the ZPE for different locations and charge states of H in Si. We show that the main contribution to the ZPE is coming from vibrations along the Si-H bonds whereas contributions from other Si atoms apart from the direct Si-H bonds play no role. It is demonstrated that accounting the ZPE reduces the hydrogen formation energy by ?0.17 eV meaning that neglecting ZPE at low temperatures one can underestimate hydrogen solubility by few orders of magnitude. In contrast, the effect of the ZPE on the ionization energy of H in Si is negligible. The results can have important implications for characterization of vibrational properties of Si by inelastic neutron scattering, as well as for theoretical estimations of H concentration in Si.

Karazhanov, S. Zh.; Ganchenkova, M.; Marstein, E. S.

2014-05-01

176

A Vibration-Based PMN-PT Energy Harvester  

Microsoft Academic Search

We report design, modeling, analysis, and experimental study of a vibration-based piezoelectric energy harvester. The energy harvester is made of a composite cantilever of a single crystal relaxor ferroelectric material, (1- x)Pb(Mg1\\/3Nb2\\/3)O3-xPbTiO3 (PMN-PT), and a polydimethylsiloxane (PDMS) base layer. A PDMS proof mass is constructed at the tip of the composite cantilever beam and is used as a means to

Alex Mathers; Kee S. Moon; Jingang Yi

2009-01-01

177

Intermolecular vibrational energy transfers in liquids and solids.  

PubMed

Resonant and nonresonant intermolecular vibrational energy transfers in KSCN/KSC(13)N/KS(13)C(15)N aqueous and DMF solutions and crystals are studied. Both energy-gap and temperature dependent measurements reveal some surprising results, e.g. inverted energy-gap dependent energy transfer rates and opposite temperature dependences of resonant and nonresonant energy transfer rates. Two competing mechanisms are proposed to be responsible for the experimental observations. The first one is the dephasing mechanism in which the measured energy transfer rate originates from the dephasing of the energy donor-acceptor coherence, and the second one is the phonon-compensation mechanism derived from the second order perturbation. It is found that both the nonresonant energy transfers in the liquids and resonant energy transfers in both liquids and solids can be well described by the first mechanism. The second mechanism explains the nonresonant energy transfers in one series of the solid samples very well. PMID:24899537

Chen, Hailong; Wen, Xiewen; Guo, Xunmin; Zheng, Junrong

2014-07-21

178

Frequency Up-Converted Low Frequency Vibration Energy Harvester Using Trampoline Effect  

NASA Astrophysics Data System (ADS)

This paper presents a non-resonant vibration energy harvester based on magnetoelectric transduction mechanism and mechanical frequency up-conversion using trampoline effect. The harvester utilizes a freely movable spherical permanent magnet which bounces off the aluminum springs integrated at both ends of the cavity, achieving frequency up-conversion from low frequency input vibration. Moreover, bonding method of magnetoelectric laminate composite has been optimized to provide higher strain to piezoelectric material and thus obtain a higher output voltage. A proof-of-concept energy harvesting device has been fabricated and tested. Maximum open-circuit voltage of 11.2V has been obtained and output power of 0.57?W has been achieved for a 50k? load, when the fabricated energy harvester was hand-shaken.

Ju, S.; Chae, S. H.; Choi, Y.; Jun, S.; Park, S. M.; Lee, S.; Lee, H. W.; Ji, C.-H.

2013-12-01

179

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

180

Broadband and band-limited random vibration energy harvesting using a piezoelectric patch on a thin plate  

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

181

Chaotic torsional vibration of imbalanced shaft driven by a limited power supply  

NASA Astrophysics Data System (ADS)

In this paper, torsional vibrations of imbalanced shaft driven by a limited power supply are studied. It is shown that mutual interaction of shaft and power supply may in particular result in chaotic self-oscillations that correspond to the strange attractors in the phase space of the coupled dynamical system "shaft-power supply". In this particular model, strange attractors represent classical Lorenz and Feigenbaum attractors. Rotation characteristic of the power supply and resonance characteristic of the shaft rotational motion in one of the resonance zones are studied. It is shown that at certain intervals, these characteristics may be non-unique, which corresponds to the case of chaotic dynamics. Such non-trivial properties of the coupled system "shaft-power supply" could be used for a better understanding of complex vibrational phenomena in real applied systems such as problems related to the damping of the torsional vibrations.

Verichev, N. N.

2012-01-01

182

Isotopic vibration--vibration energy exchange in hydrogen chloride molecules at low temperatures  

SciTech Connect

The temperature dependence of the isotopic VV energy exchange process H/sup 35/Cl(1)+H/sup 37/Cl(0)..-->..H/sup 35/Cl(0)+H/sup 37/Cl(1) has been studied in the temperature range of 10--1000 K. As temperature increases the VV probability increases between 10--30 K, but above 50 K it decreases rapidly. The appearance of two regions of different temperature dependence has been discussed in terms of the local translational motion which causes the vibrational modes of two colliding molecules to couple efficiently in the presence of strong attractive interaction.

Shin, H.K.

1985-02-01

183

Design, Modeling, and Performance Measurements of a Broadband Vibration Energy Harvester Using a Magnetoelectric Transducer  

Microsoft Academic Search

This article presents a new broadband vibration energy harvester using a magnetoelectric (ME) transducer. In order for vibration energy harvesters to be efficiently applicable over a range of vibration frequencies, many techniques have recently been investigated to broaden the frequency ranges of the harvesters using piezoelectric, electromagnetic, or electrostatic transductions, but few have been studied in the harvesters using ME

Jin Yang; Yumei Wen; Ping Li; Xianzhi Dai

2011-01-01

184

Energy absorption of seated occupants exposed to horizontal vibration and role of back support condition.  

PubMed

Absorbed power characteristics of seated human subjects under fore-aft (x-axis) and lateral (y-axis) vibration are investigated through measurements of dynamic interactions at the two driving-points formed by the body and the seat pan, and upper body and the backrest. The experiments involved: (i) three back support conditions (no back support, and back supported against a vertical and an inclined backrest); (ii) three seat pan heights (425, 390 and 350 mm); and three magnitudes (0.25, 0.5 and 1.0 m/s2 rms acceleration) of band limited random excitations in 0.5-10 Hz frequency range, applied independently along the x- and y- axes. The force responses, measured at the seat pan and the backrest are applied to characterize total energy transfer reflected on the seat pan and the backrest. The mean responses suggest strong contributions due to back support, and direction and magnitude of vibration. In the absence of a back support, the seat pan responses dominated in lower frequency bands centered at 0.63 and 1.25 Hz under both directions of motion. Most significant interactions of the upper body against the back support was observed under fore-aft vibration. The addition of back support caused the seat pan response to converge to a single primary peak near a higher frequency of 4 Hz under x- axis, with only little effect on the y-axis responses. The back support serves as an additional source of vibration to the occupant and an important constraint to limit the fore-aft movement of the upper body and thus relatively higher energy transfer under. The mean responses were further explored to examine the Wd frequency-weighting used for assessing exposure to horizontal vibration. The results show that the current weighting is suited for assessing the vibration exposure of human subjects seated only without a back support. PMID:19088407

Rakheja, Subhash; Mandapuram, Santosh; Dong, Ren G

2008-12-01

185

Energy Harvesting from Ambient Vibrations with Arbitrary In-Plane Motion Directions Using a Magnetostrictive/Piezoelectric Laminate Composite Transducer  

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

186

Energy Harvesting from Ambient Vibrations with Arbitrary In-Plane Motion Directions Using a Magnetostrictive/Piezoelectric Laminate Composite Transducer  

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 0.6g (with g = 9.8 m s-2).

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

2014-05-01

187

Resonant vibrational excitation of CO by low-energy electrons  

SciTech Connect

Electron impact vibrational excitation of the CO molecule, via the {sup 2}{pi} resonance, in the 0-4 eV energy region has been investigated. The energy dependence of the resonant excitation of the first ten vibrational levels, v=1 to v=10, has been measured by use of a crossed-beams double trochoidal electron spectrometer. Obtained relative differential cross sections are normalized to the absolute values. Integral cross sections are determined by using our recent results on scattered electrons angular distributions, which demonstrate clear p-partial wave character of this resonance. Substructures appear in the {sup 2}{pi} resonant excitation of the CO molecule which have not been previously observed.

Poparic, G. B.; Belic, D. S.; Vicic, M. D. [Faculty of Physics, University of Belgrade, Studentski trg 12-16, P.O. Box 368, 11000 Belgrade (Serbia and Montenegro); Washington University School of Medicine, 4921 Parkview Place, Campus Box 8224, St. Louis, Missouri 63110-1093 (United States)

2006-06-15

188

Vibrational spectroscopy and energy relaxation of nanocubes, nanoboxes, and nanocages  

NASA Astrophysics Data System (ADS)

Irradiating metal particles by an ultrafast laser pulse produces rapid heating of the lattice. This can lead to coherent excitation of the vibrational modes of the particle that correlate with the expansion co-ordinates. By comparing the measured periods to continuum mechanics calculations, these experiments can provide information about the elastic constants of the particle if the size and shape are known. In this paper recent results are presented for particles with cubic symmetry, specifically, nanocubes, nanoboxes (hollow cubes) and nanocages (nanoboxes with holes on the corners and/or facets of the box). The way the vibrational modes are assigned, and the information content of the experiments will be discussed, as well as the energy relaxation dynamics of the particles. Energy relaxation is important for the proposed use of the nanocages in phothermal therapy, where heat dissipation following laser excitation is used to selectively kill cells.

Petrova, Hristina; Lin, Chien-Hua; De Leijer, Susanna; Hu, Min; McLellan, Joseph M.; Siekkinen, Andrew R.; Wiley, Benjamin J.; Marquez, Manuel; Xia, Younan; Sader, John E.; Hartland, Gregory V.

2006-09-01

189

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

PubMed

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. PMID:24712778

Deyne, Andy Van Yperen-De; De Meyer, Thierry; Pauwels, Ewald; Ghysels, An; De Clerck, Karen; Waroquier, Michel; Van Speybroeck, Veronique; Hemelsoet, Karen

2014-04-01

190

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

NASA Astrophysics Data System (ADS)

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; De Meyer, Thierry; Pauwels, Ewald; Ghysels, An; De Clerck, Karen; Waroquier, Michel; Van Speybroeck, Veronique; Hemelsoet, Karen

2014-04-01

191

Vibration energy harvesting using a spherical permanent magnet  

NASA Astrophysics Data System (ADS)

The authors recently reported on a hybrid rotary-translational vibration energy harvesting approach using a spherical permanent-magnet and employing cycloidal motion as a mechanical amplifier. The rotary-translational harvesting approach, which is resonant in nature, can yield approximately twice the e.m.f. compared with a similar translationalonly device. This paper explores the analytic and numerical modelling of the rotary-translational harvester with the goal of finding an efficient method for design optimisation.

Moss, Scott D.; Hart, Genevieve A.; Burke, Stephen K.; Galea, Steve C.; Carman, Gregory P.

2014-04-01

192

Improved Energy Harvesting from Wideband Vibrations by Nonlinear Piezoelectric Converters  

Microsoft Academic Search

Vibration harvesters typically are linear mass-spring devices working at resonance. A different approach is here proposed based on nonlinear converters that exploit stochastic resonance with white-noise excitation. A piezoelectric beam converter is coupled to permanent magnets creating a bistable system bouncing between two stable states in response to random excitation. Under proper conditions, this significantly improves energy harvesting from wide-spectrum

Marco Ferrari; Vittorio Ferrari; Michele Guizzetti; Bruno Andò; Salvatore Baglio; Carlo Trigona

2009-01-01

193

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

194

Development of a three-axis active vibration isolator using zero-power control  

Microsoft Academic Search

This paper presents the development of an active 3-degree-of-freedom (DoF) vibration isolation system using zero-power magnetic suspension. The developed system is capable to suppress direct disturbances and isolate ground vibrations of the 3-DoF motions, associated with vertical translational and rotational modes. Two categories of control strategy for the actuators are proposed, i.e., local control and mode control. The latter method

M. Takasaki; Y. Ishino; T. Mizuno

2006-01-01

195

System Analysis of Blood Circulation Based on Coherence Power Transfer: From Electrical Driving to Mechanical Vibration  

NASA Astrophysics Data System (ADS)

We analyze blood circulation based on the basis of the system viewpoint and coherence power transfer from electrical energy (ECG) to mechanical power (blood pressure wave). The coherent oscillation between the driving signal and the vibration of the cardiovascular system is investigated by coherence function and the perturbations of the system are found. In addition, we develop a mathematical equation to describe the phenomenon. The average peak coherence value S for the first five harmonics is utilized as an index to quantify the power coherence effect. The evaluated p-value (< 0.01) reveals that the distinction of power coherence between the healthy subjects and cardiovascular patients is significant. Consequently, we conclude that if the S approaches a value close to one, the output is almost completely attributed to input and fewer perturbation signals influence the system; therefore, the cardiovascular system stays in a better condition. Conversely, if S approaches a value less than one, larger perturbations will worsen the cardiovascular system condition.

Wei, Ching?Chuan; Lo, Pei?Chen; Wu, Lin?Kun

2006-04-01

196

Rotational and vibrational energy effect on energy-resolved emission of anthracene and 9-cyanoanthracene  

NASA Astrophysics Data System (ADS)

We report on the study of intramolecular vibrational energy redistribution (IVR) in vibrationally cold anthracene and 9-cyanoanthracene. These molecules were expanded with argon from a pulsed linear nozzle and were excited by a tunable dye laser. IVR was probed mostly through the rotational and vibrational energy dependence of the resulting energy-resolved emission. The existence of vibrational mixing in the form of Fermi resonances is demonstrated. Large rotational effects were found and the energy-resolved emission was found to be very sensitive to the exact excitation wavelength of the exciting laser within the rotational contour. We have concluded that both anharmonic coupling and Coriolis coupling are important intrastate vibronic couplings. Intrastate IVR is shown to be associated with enhanced interstate electronic relaxation. The possible co-existence of Coriolis coupling and quantum beats in the time- and energy-resolved emission is discussed.

Amirav, Aviv

1988-08-01

197

Calculation of vibrational zero-point energy  

Microsoft Academic Search

We have established an empirical formula for calculating the zero-point energy (ZPE) of organic compounds. We applied this formula to 80 molecular systems, and compared it to the AM1 semi-empirical method, in both cases with satisfactory results. We also observed that the sum ZPE+H(T)?H(0) and the empirically derived ZPE(empirical) are related by a quasi-linear relation.

M. Rahal; M. Hilali; A. El Hammadi; M. El Mouhtadi; A. El Hajbi

2001-01-01

198

Nonresonant and resonant mode-specific intermolecular vibrational energy transfers in electrolyte aqueous solutions.  

PubMed

The donor/acceptor energy mismatch and vibrational coupling strength dependences of interionic vibrational energy transfer kinetics in electrolyte aqueous solutions were investigated with ultrafast multiple-dimensional vibrational spectroscopy. An analytical equation derived from the Fermi's Golden rule that correlates molecular structural parameters and vibrational energy transfer kinetics was found to be able to describe the intermolecular mode specific vibrational energy transfer. Under the assumption of the dipole-dipole approximation, the distance between anions in the aqueous solutions was obtained from the vibrational energy transfer measurements, confirmed with measurements on the corresponding crystalline samples. The result demonstrates that the mode-specific vibrational energy transfer method holds promise as an angstrom molecular ruler. PMID:21916443

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

2011-10-27

199

Vibration-Induced Changes in the Contact Resistance of High Power Electrical Connectors for Hybrid Vehicles  

Microsoft Academic Search

Relatively little is known about the fretting mechanism of high power connectors used in hybrid vehicles, even though the vehicles are widely being introduced to the market. This paper experimentally investigates the fretting mechanisms of silver-plated high power connectors caused by vibrations. In order to emulate operational and environmental effects, a test stand was designed that is capable of measuring

Rujian Fu; Song-Yul Ben Choe; Robert L. Jackson; George T. Flowers; Michael J. Bozack; Liang Zhong; Daegee Kim

2012-01-01

200

Modeling and Analysis of Vibration-Induced Changes in Connector Resistance of High Power Electrical Connectors for Hybrid Vehicles  

Microsoft Academic Search

High power connectors used in hybrid vehicles are exposed to vibrations that cause changes in connector resistance. When vibration starts, the connector resistance increases temporarily and oscillates. When vibration stops, the connector resistance returns to a value that is similar to the original state. In this paper, finite element models are developed to analyze this phenomenon and compared with experimental

Rujian Fu; Song-Yul Choe; Robert L. Jackson; George T. Flowers; Daegee Kim

2012-01-01

201

Regional Calibration of Seismic Stations Using High-power Vibrators: A Technique, First Outcomes, Future Prospects  

NASA Astrophysics Data System (ADS)

The outcomes of work under the IRC project 1067 "Creation of calibration technology of seismic stations and seismic traces with use of high-power seismic vibrators", which was fulfilled by the Institute of Computational Mathematics and Mathematical Geo- physics SB RAS, Altai-Sayan Experimental Seismological Expedition SB RAS and Research Institute of Impulse Engineering of Russia Minatom, are given. The project is connected to problems of station calibration of an international system of monitor- ing of the Agreement of Mutual Ban of Nuclear Tests and provided for a research of wave fields of high-power vibrators and industrial explosions Within the realization of the project plan the researches on recording a high-power 100-ton fixed vibrator (located on a proving ground of Novosibirsk) on the areal aperture on distances to 400 km have been carried out. From recording results is shown that from a high-power vibrator of a vertical force reference waves from the interfaces in the Earth's crust (di- rect Pg-, Sg-, reflected PkP-, SkS-waves) and the Moho discontinuity (Pn-, Sn-, PmP-, SmS-waves) are stably recorded. The comparison of wave fields from a vibrator and industrial explosions has been made and the perspective scheme of station calibration (international and local network) with use of high-power fixed and movable vibrators has been developed. Basic outcomes of the project can be formulated as follows: 1) the perspective scheme of seismic station calibration of the international network on distances of 1500-2000 km using of vibrators of the increased power (more than 1000 tons of a force) has been grounded; 2) the calibration of seismic stations on distances of 500 - 1500 km has been developed and tested on practical examples on basis of combined method with use of data from vibrators of an average power (60-100-ton of a force) and information from seismological networks of earthquakes and indus- trial explosions; 3) from movable vibrators of low power (40-60-ton of a force) the correlograms with records of waves in the first arrivals on distances in 200-250 km have been obtained that shows an outlook of their use for obtaining of high-velocity characteristics in seismic stations outskirts and sources in a radius of 150-250 km.

Seleznev, V. S.; Emanov, A. F.; Soloviev, V. M.; Glinsky, B. M.; Kashun, V. N.

202

Theoretical investigations of energy harvesting efficiency from structural vibrations using piezoelectric and electromagnetic oscillators.  

PubMed

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

203

Repulsively driven frequency-increased-generators for durable energy harvesting from ultra-low frequency vibration  

NASA Astrophysics Data System (ADS)

An electromagnetic kinetic energy harvester has been developed, which can convert ultra-low-frequency motion and vibration energy into electrical power. This harvester employs a two-stage vibratory structure to collect low-frequency kinetic energy and effectively transfer it into electric power by using a pair of high-frequency resonant generators. Non-contact magnetic repulsive force is herein utilized for the 1st-stage sliding vibrator to drive the 2nd-stage resonators into frequency-up-conversion resonance. The non-contact actuation is helpful for durable and long-life working of the device. The prototyped device is fabricated and the design is well confirmed by experimental test. The harvester can be well operated at the frequency as low as 0.25 Hz. Under driving acceleration of 1 g at 0.5 Hz, the miniaturized harvester can generate a peak power of 4.42 mW and an average power of 158 ?W.

Tang, Qiaochu; Yang, Yongliang; Li, Xinxin

2014-04-01

204

Repulsively driven frequency-increased-generators for durable energy harvesting from ultra-low frequency vibration.  

PubMed

An electromagnetic kinetic energy harvester has been developed, which can convert ultra-low-frequency motion and vibration energy into electrical power. This harvester employs a two-stage vibratory structure to collect low-frequency kinetic energy and effectively transfer it into electric power by using a pair of high-frequency resonant generators. Non-contact magnetic repulsive force is herein utilized for the 1st-stage sliding vibrator to drive the 2nd-stage resonators into frequency-up-conversion resonance. The non-contact actuation is helpful for durable and long-life working of the device. The prototyped device is fabricated and the design is well confirmed by experimental test. The harvester can be well operated at the frequency as low as 0.25 Hz. Under driving acceleration of 1 g at 0.5 Hz, the miniaturized harvester can generate a peak power of 4.42 mW and an average power of 158 ?W. PMID:24784650

Tang, Qiaochu; Yang, Yongliang; Li, Xinxin

2014-04-01

205

Bimolecular reactions and energy-transfer processes of highly vibrationally excited molecules related to energetic materials  

NASA Astrophysics Data System (ADS)

Infrared Multiphoton Absorption (IRMPA) was used to produce populations of vibrationally excited 1,1,2-trifluoroethane, which were characterized by optoacoustic measurements of absorbed laser power and collision free decomposition yields. The measurements were accurately fitted with a Master Equation that included Quack's theory of IRMPA, three RKM unimolecular reaction channels, and collisional energy transfer. The highly constrained adjustable parameters indicate that the optical coupling matrix elements are dramatically reduced in magnitude near reaction threshold energies where vibrational anharmonicity becomes important. Observed infrared fluorescence from the excited molecules is in excellent agreement with Master Equation predictions and it was used to monitor collisional deactivation of the excited molecules. The energy transfer exhibits a weak vibrational energy on bimolecular reactions of 1,1 2-trifluorethane (TFE), but no such effects have yet been observed. A Monte Carlo method is described for efficient multidimensional integration not restricted to hyper-dimensional rectangles, but applied to more complicated domains. When known, the boundaries of a arbitrary integration region can be used to define the sampling domain, resulting in sampling with unit efficiency.

Barker, John R.

1987-12-01

206

Separation of time variant vibration sources by short time coherent output power  

NASA Astrophysics Data System (ADS)

This effort describes the use of time variant coherence causality based analysis to separate the effects of nonstationary time variant vibration excitation sources. A time variant coherence function using the Short Time Fourier Transform (STFT) is first discussed. The concept of a time variant coherent output power for source separation of systems with time variant transfer functions is developed. A parametric study is performed to examine the coherent output power separation capabilities with respect to the data processing parameters. The study guided the selection of the time-frequency processing parameters judged to provide a suitable compromise between the time event localization and output amplitude source separation. The time variant coherent output power is then applied to separate the effects of the two possible excitation sources on the prototype vibration isolation floor. The application was a subscale prototype isolation floor for a proposed vibration sensitive equipment site adjacent to a busy freight rail line. The moving train created time variant transmission paths. As there was a direct line of sight between the prototype floor and the rail line there was an airborne acoustic excitation path in addition to a ground path. The short time coherent output power was applied to separate prototype isolation floor vibration into respective components related to the two candidate sources. The analysis and discussion of the results focuses upon the interpretation and issues in such a complicated realistic environment. Ultimately the application was successful providing an explanation as to why the observed vibration isolation was degraded at higher frequencies.

Trethewey, Martin W.

2011-02-01

207

Optimized energy harvesting from mechanical vibrations through piezoelectric actuators, based on a synchronized switching technique  

NASA Astrophysics Data System (ADS)

Increasing demand in mobile, autonomous devices has made energy harvesting a particular point of interest. Systems that can be powered up by a few hundreds of microwatts could feature their own energy extraction module. Energy can be harvested from the environment close to the device. Particularly, the ambient mechanical vibrations conversion via piezoelectric transducers is one of the most investigated fields for energy harvesting. A technique for optimized energy harvesting using piezoelectric actuators called "Synchronized Switching Harvesting" is explored. Comparing to a typical full bridge rectifier, the proposed harvesting technique can highly improve harvesting efficiency, even in a significantly extended frequency window around the piezoelectric actuator's resonance. In this paper, the concept of design, theoretical analysis, modeling, implementation and experimental results using CEDRAT's APA 400M-MD piezoelectric actuator are presented in detail. Moreover, we suggest design guidelines for optimum selection of the storage unit in direct relation to the characteristics of the random vibrations. From a practical aspect, the harvesting unit is based on dedicated electronics that continuously sense the charge level of the actuator's piezoelectric element. When the charge is sensed, to come to a maximum, it is directed to speedily flow into a storage unit. Special care is taken so that electronics operate at low voltages consuming a very small amount of the energy stored. The final prototype developed includes the harvesting circuit implemented with miniaturized, low cost and low consumption electronics and a storage unit consisting of a super capacitors array, forming a truly self-powered system drawing energy from ambient random vibrations of a wide range of characteristics.

Tsampas, P.; Roditis, G.; Papadimitriou, V.; Chatzakos, P.; Gan, Tat-Hean

2013-05-01

208

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

209

Mechanism of emergence of intense vibrations of turbines on the Sayano-Shushensk hydro power plant  

NASA Astrophysics Data System (ADS)

It is demonstrated that the level of vibrations of turbines on the Sayano-Shushensk hydro power plant is enhanced by the capability of a compressible fluid to perform its own hydroacoustic oscillations (which can be unstable) in the turbine duct. Based on the previously obtained results of solving the problem of natural hydroacoustic oscillations in the turbine duct and some ideas about turbine interaction with an unsteady compressible fluid flow, results of full-scale studies of turbine vibrations and seismic monitoring of the dam of the Sayano-Shushensk hydro power plant before and during the accident are analyzed.

Kurzin, V. B.; Seleznev, V. S.

2010-07-01

210

Electronic resonance with anticorrelated pigment vibrations drives photosynthetic energy transfer outside the adiabatic framework  

PubMed Central

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.

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

2013-01-01

211

Electronic resonance with anticorrelated pigment vibrations drives photosynthetic energy transfer outside the adiabatic framework.  

PubMed

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

212

Mode-specific energy absorption by solvent molecules during CO2 vibrational cooling.  

PubMed

Non-equilibrium molecular dynamics (NEMD) simulations of energy transfer from vibrationally excited CO(2) to CCl(4) and CH(2)Cl(2) solvent molecules are performed to identify the efficiency of different energy pathways into the solvent bath. Studying in detail the work performed by the vibrationally excited solute on the different solvent degrees of freedom, it is shown that vibration-to-vibration (V-V) processes are strongly dominant and controlled by those accepting modes which are close in frequency to the CO(2) bend and symmetric stretch vibration. PMID:17396180

Kandratsenka, Alexander; Schroeder, Jörg; Schwarzer, Dirk; Vikhrenko, Vyacheslav S

2007-04-14

213

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

214

Analysis of Nonlinear Spring Arm for Improved Performance of Vibrational Energy Harvesting Devices  

NASA Astrophysics Data System (ADS)

Recently, a number of attempts have been made to increase the operational bandwidth of the energy harvesting devices. Nonlinear mechanisms are one of them. In this paper, we report design and analytical formulation of stretching strain of an electromagnetic energy harvester on FR4 material under large deformation of the spring arms. It is found that nonlinearity has an inverse square dependence on thickness of the arms. Numerical solution of a monostable Duffing oscillator that governs the dynamics of such a large deformed nonlinear energy harvester showed that with decrease of load resistance, the average power output increases, where the output response depends strongly on the input force. For small input acceleration, the desired large amplitude vibration does not come into play and the response becomes linear. However, for higher input acceleration nonlinearity appears and the operational bandwidth increases, at the same time, output power level also increases.

Mallick, D.; Amann, A.; Roy, S.

2013-12-01

215

A review of the recent research on vibration energy harvesting via bistable systems  

NASA Astrophysics Data System (ADS)

The investigation of the conversion of vibrational energy into electrical power has become a major field of research. In recent years, bistable energy harvesting devices have attracted significant attention due to some of their unique features. Through a snap-through action, bistable systems transition from one stable state to the other, which could cause large amplitude motion and dramatically increase power generation. Due to their nonlinear characteristics, such devices may be effective across a broad-frequency bandwidth. Consequently, a rapid engagement of research has been undertaken to understand bistable electromechanical dynamics and to utilize the insight for the development of improved designs. This paper reviews, consolidates, and reports on the major efforts and findings documented in the literature. A common analytical framework for bistable electromechanical dynamics is presented, the principal results are provided, the wide variety of bistable energy harvesters are described, and some remaining challenges and proposed solutions are summarized.

Harne, R. L.; Wang, K. W.

2013-02-01

216

Modeling and simulation of linear and nonlinear MEMS scale electromagnetic energy harvesters for random vibration environments.  

PubMed

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

217

Modeling and Simulation of Linear and Nonlinear MEMS Scale Electromagnetic Energy Harvesters for Random Vibration Environments  

PubMed Central

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.

Sassani, Farrokh

2014-01-01

218

Analytical modeling and experimental verification of vibration-based piezoelectric bimorph beam with a tip-mass for power harvesting  

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

219

A wideband, frequency up-converting bounded vibration energy harvester for a low-frequency environment  

NASA Astrophysics Data System (ADS)

This paper presents a bounded vibration energy harvester to effectively harvest energy from a wide band of low-frequency environmental vibrations ranging from 10 to 18 Hz. Rigid mechanical stoppers are used to confine the seismic mass movement within the elastic limits of the spring. Experimental results show the effectiveness of the proposed technique in increasing the efficiency of the energy harvester. When excited at a frequency of 10 Hz with a peak acceleration of 1 g, the harvester responds at a higher frequency of 20 Hz and gives a peak power of 2.68 mW and a peak to peak voltage of 2.62 V across a load of 220 ?. The average power density of 65.74 ?W cm-3 obtained at 10 Hz 1 g excitation monotonically increases with frequency up to 341.86 ?W cm-3 at 18 Hz. An analytical model describing the nonlinear dynamics of the proposed harvester is also presented. A simple technique to estimate the energy losses during impact and thereof a method to incorporate these losses in the model are suggested. The presented model not only predicts the experimental voltage waveform and frequency response of the device with good similarity but also predicts the RMS voltage from the harvester for the whole range of operating frequencies with an RMS error of 5.2%.

Ashraf, K.; Khir, M. H. Md; Dennis, J. O.; Baharudin, Z.

2013-02-01

220

Vibration energy harvesting using a phononic crystal with point defect states  

NASA Astrophysics Data System (ADS)

A vibration energy harvesting generator was studied in the present research using point-defect phononic crystal with piezoelectric material. By removing a rod from a perfect phononic crystal, a resonant cavity was formed. The elastic waves in the range of gap frequencies were all forbidden in any direction, while the waves with resonant frequency were localized and enhanced in the resonant cavity. The collected vibration energy was converted into electric energy by putting a polyvinylidene fluoride film in the middle of the defect. This structure can be used to simultaneously realize both vibration damping and broad-distributed vibration energy harvesting.

Lv, Hangyuan; Tian, Xiaoyong; Wang, Michael Yu; Li, Dichen

2013-01-01

221

Effects of vibration and shock on the performance of gas-bearing space-power Brayton cycle turbomachinery. 2: Sinusoidal and random vibration  

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

222

Efficiency improvement in a vibration power generator for a linear MR damper: numerical study  

NASA Astrophysics Data System (ADS)

This paper summarizes a numerical analysis of the electromagnetic field, voltage and circuit properties and the cogging force in a vibration power generator comprising permanent magnets and a coil with a foil winding. The device converts the energy harvested from vibrations into electrical energy which is next used to vary the damping characteristics of a linear MR damper attached to the generator. The objective of the study is to propose a sufficiently efficient generator whose finally developed (target) version could be integrated with a small-scale MR damper to build a single device. Two design options for the device are numerically studied, the previously engineered generator 1 and the newly devised generator 2. Generator 1 incorporates two magnet systems having four magnets each and a single-section coil, while generator 2 comprises three magnet systems with four magnets each and a two-section coil. Calculations were performed to determine the electromagnetic field, voltage and current properties and the cogging force in the generators. The electromagnetic field parameters include the distribution of the magnetic field, the electrical potential field and the current density in the open turn and closed turn of the generators’ coils. The voltage and current properties include electromotive force (emf) in the generators and the voltage, current, instantaneous power and energy of the magnetic field in the MR damper control coil which is represented by resistance parameter R and inductance parameter L. The cogging force expresses the magnetic interactions between the permanent magnet systems and ferromagnetic structural components of the generators. The occurrence of this force is very unfavourable and attempts should be made to reduce it through control of the parameters of the magnetic circuit components. On one hand, comparison of the numerical results for the electromagnetic field parameters and voltage and current properties revealed that for the predetermined RL parameters of the MR damper control coil, generator 2 seems to be more efficient than generator 1 and hence is more suitable for supplying the MR damper. On the other hand, comparison of the calculated cogging force levels revealed that its value tends to be lower in generator 1. It is reasonable to suppose that development of a final version of the generator with the defined structure and enhanced efficiency would have to involve some trade-off between the emf and the cogging force.

Sapi?ski, Bogdan; Krupa, Stanis?aw

2013-04-01

223

Calculations of vibration-rotation energy levels of HD sup +  

SciTech Connect

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{sup +}. All nonadiabatic effects, except for part of the coupling of rotational and electronic angular momenta, are accounted for. The results, which are for {ital v}=0--21, {ital 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 {ital J}{ne}0 levels to allow for the remaining contribution of {Pi} electronic states permits comparison with experimental transition energies. The agreement is excellent.

Balint-Kurti, G.G. (School of Chemistry, The University, Bristol BS81TS, England (GB)); Moss, R.E.; Sadler, I.A. (Chemistry Department, The University, Southampton SO95NH (England)); Shapiro, M. (Department of Chemical Physics, The Weizmann Institute of Science, Rehovot (Israel))

1990-05-01

224

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

225

Localization of high-frequency vibrations of secondary systems of power plants  

Microsoft Academic Search

Summary The papers addresses a new approach for more accurate dynamic design of secondary systems and components of nuclear power plants at high frequencies. This approach is based on a precise consideration of a structural member with the rest of the structure being described integrally. The concept is applied to analyse the transition of high-frequency vibrations through non-anchored coupling of

A. K. Belyaev; N. J. Krutzik

1994-01-01

226

The vibrational energy pattern in acetylene (IV): Updated global vibration constants for 12C2H2  

NASA Astrophysics Data System (ADS)

All 253 vibrational levels in the ground electronic state of 12C2H2 with assigned rotational structure reported in the literature from absorption, stimulated emission pumping, and dispersed laser induced fluorescence spectroscopic investigations are gathered. They cover the range up to 18 915 cm-1. Some 219 of these energies are simultaneously fitted using the same so-called Cluster model based on the emergence of three constants of the motion, as previously used to deal with the vibrational energy levels up to 12 000 cm-1 [Abbouti Temsamani and Herman, J. Chem. Phys. 103, 5931 (1995)]. Thirty-nine vibrational constants are produced. The rms value of the fit is 0.81 cm-1. Principal rotational constants are predicted for all levels, which satisfactorily compare with the experimental results. Problems are demonstrated to concern a fraction of the 34 remaining levels only. Thus, the adequacy of the model is fully confirmed. The remaining problems are discussed and globally attributed to problems of a vibration-rotation nature. A comprehensive listing of calculated vibrational energies for all k sublevels up to 15 000 cm-1, including predicted Bv values and assignments is made available.

El Idrissi, M. I.; Liévin, J.; Campargue, A.; Herman, M.

1999-01-01

227

Multiphysics finite element model of a frequency-amplifying piezoelectric energy harvester with impact coupling for low-frequency vibrations  

NASA Astrophysics Data System (ADS)

This paper presents experimentally-verified multiphysics finite element model of a wideband vibration energy harvester with impact coupling, which operates on the principle of frequency up-conversion: under low-frequency harmonic base excitation a cantilever-type resonator (with resonant frequency of 18.8 Hz) impacts a high-frequency piezoelectric cantilever, which starts freely vibrate at its resonant frequency of 374 Hz. Such input frequency amplification enables efficient power generation under low-frequency ambient excitations. The model was implemented in COMSOL and the contact between the cantilevers was formulated by using a nonlinear viscoelastic model. Reported results of dynamical and electrical testing of the fabricated vibration energy harvester confirm the accuracy of the model as well as reveal some operational characteristics of the device under varying impact and excitation conditions.

Dauksevicius, R.; Briand, D.; Vásquez Quintero, A.; Lockhart, R. A.; Janphuang, P.; de Rooij, N. F.; Ostasevicius, V.

2013-12-01

228

Adhesion energy characterization of monolayer graphene by vibrational spectroscopy  

NASA Astrophysics Data System (ADS)

As at nano/micro-scale van der Waals forces often dominate various other types of forces, the accurate adhesion characterization of graphene (Gr) is essential to its processing, manipulation, and possible integration into integrated circuits and other nano/micro-scale devices. Since 2010, the reported (experimental) adhesion energy of monolayer Gr with silicon dioxide (SiO2) has increased from 151 +/- 28 mJ/m2 to 450 +/- 20 mJ/m2. Here, we report a set of adhesion energy values for Gr monolayers on a SiO2 substrate by adopting a unique vibrational spectroscopy approach based on the motion of adhesive microparticles on a vibrating substrate. The reported results indicate that the work-of-adhesion measurements of monolayer Gr on SiO2 could be highly scattered and its mean value is determined as WSiO2-Gr = 1160.26 mJ/m2, which is the highest value reported to date. Unlike the reported existing methods, the current non-contact and non-destructive spectral technique requires no knowledge of the mechanical properties of Gr. Based on the reported data, with the current approach, it is also demonstrated that the weak adhesive interactions between a polystyrene latex microparticle and SiO2 substrate across the monolayer Gr can be detected as well.

Vahdat, Armin Saeedi; Cetinkaya, Cetin

2013-10-01

229

Power management for energy harvesting wireless sensors  

NASA Astrophysics Data System (ADS)

The objective of this work was to demonstrate smart wireless sensing nodes capable of operation at extremely low power levels. These systems were designed to be compatible with energy harvesting systems using piezoelectric materials and/or solar cells. The wireless sensing nodes included a microprocessor, on-board memory, sensing means (1000 ohm foil strain gauge), sensor signal conditioning, 2.4 GHz IEEE 802.15.4 radio transceiver, and rechargeable battery. Extremely low power consumption sleep currents combined with periodic, timed wake-up was used to minimize the average power consumption. Furthermore, we deployed pulsed sensor excitation and microprocessor power control of the signal conditioning elements to minimize the sensors" average contribution to power draw. By sleeping in between samples, we were able to demonstrate extremely low average power consumption. At 10 Hz, current consumption was 300 microamps at 3 VDC (900 microwatts); at 5 Hz: 400 microwatts, at 1 Hz: 90 microwatts. When the RF stage was not used, but data were logged to memory, consumption was further reduced. Piezoelectric strain energy harvesting systems delivered ~2000 microwatts under low level vibration conditions. Output power levels were also measured from two miniature solar cells; which provided a wide range of output power (~100 to 1400 microwatts), depending on the light type & distance from the source. In summary, system power consumption may be reduced by: 1) removing the load from the energy harvesting & storage elements while charging, 2) by using sleep modes in between samples, 3) pulsing excitation to the sensing and signal conditioning elements in between samples, and 4) by recording and/or averaging, rather than frequently transmitting, sensor data.

Arms, S. W.; Townsend, C. P.; Churchill, D. L.; Galbreath, J. H.; Mundell, S. W.

2005-05-01

230

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

231

Energy-harvesting power sources for very-high-G gun-fired munitions  

Microsoft Academic Search

Several novel classes of piezoelectric-based energy-harvesting power sources are presented for very high-G gun-fired munitions (40,000 - 240,000 Gs). The power sources are designed to harvest energy from the firing acceleration and in certain applications also from in-flight vibrations. The harvested energy is converted to electrical energy for powering onboard electronics, and can provide enough energy to eliminate the need

J. Rastegar; R. Murray; C. Pereira; H.-L. Nguyen

2010-01-01

232

Design considerations for small-scale wind energy harvesters driven by broadband vortex-induced vibrations  

NASA Astrophysics Data System (ADS)

In recent years, an increasing number of breakthroughs have been made in the field of small-scale wind energy harvesting, where specialized materials are utilized to convert flow energy into electric power. Several studies on this power extraction rely on a common energy harvester setup in which a stiff cantilever beam is attached to the trailing edge of a miniature bluff body. At these small scales where boundary layer effects are appreciable in the laminar flow regime, periodic vortex shedding can be used to drive transverse vibrations in the beam. Interestingly, the fluid dynamics involved in this unsteady process have been studied for decades not to exploit their characteristics, but instead to eliminate potentially destructive effects. As a result, there is still much room for improvement and expansion on recent design studies. A study of how subtle changes in bluff body trailing edge geometry effect power output of a model will be presented in this paper. The model under consideration consists of a miniature bluff body on the order of tens of millimeters in diameter, to which a piezoelectric cantilever is attached at the trailing edge. This model is specifically designed for laminar to transitional Reynolds Number flows (500-2800) where the periodicity of vortex shedding approaches the natural frequency of the beam. As the flow speed is further increased, the effect of lock-in occurs where the resonant beam motion resists a change in vortex shedding frequency. Vibration amplitudes of the beam reach a maximum under this condition, thus maximizing power generation efficiency of the system and providing an optimal condition to operate the harvester. In an effort to meaningfully compare the results, a number of dimensionless parameters are employed. The influence of parameters such as beam length and natural frequency, fluid flow speed, and trailing edge geometry are studied utilizing COMSOL Multiphysics laminar, fluid-structure interaction simulations in order to create design guidelines for an improved energy harvester.

Paxson, Benjamin; Wickenheiser, Adam M.

2014-04-01

233

A high-power linear ultrasonic motor using longitudinal vibration transducers with single foot.  

PubMed

A high-power linear ultrasonic motor using longitudinal vibration transducers with single foot was proposed in this paper. The stator of proposed motor contains a horizontal transducer and a vertical transducer. Longitudinal vibrations are superimposed in the stator and generate an elliptical trajectory at the driving foot. The sensitivity analysis of structural parameters to the resonance frequencies of two working modes of the stator was performed using the finite element method. The resonance frequencies of two working modes were degenerated by adjusting the structural parameters. The vibration characteristics of stator were studied and discussed. A prototype motor was fabricated and measured. Typical output of the prototype is a no-load speed of 1160 mm/s and maximum thrust force of 20 N at a voltage of 200 V(rms). PMID:20679015

Liu, Yingxiang; Chen, Weishan; Liu, Junkao; Shi, Shengjun

2010-08-01

234

A method for analyzing vibration power absorption density in human fingertip  

NASA Astrophysics Data System (ADS)

In the current study, we hypothesize that the vibration power absorption density (VPAD) is a good measure for the vibration exposure intensity of the soft tissues of the fingers. In order to calculate the VPAD at a fingertip, we proposed a hybrid modeling approach, which combines a 2D finite element (FE) model with a lumped parameter model. Whereas the lumped components are used to represent the global biodynamic characteristics of the hand-arm system, the FE component is used to predict the detailed stresses, strains, and VPAD in the fingertip. The lumped parameters are determined by using the vibration transmissibilities measured at the fingertip, while the material parameters of the soft and hard tissues of the FE model are adopted from the published experimental data. The proposed model was applied to predict the distributions of dynamic displacement, velocity, and VPAD in the soft tissues of the fingertip. Furthermore, we have derived the frequency weighting based on the VPAD of the soft tissue. The preliminary analysis indicated that the VPAD-based frequency weighting is substantially different from the ISO weighting in that the ISO frequency weighting emphasizes the effect of the vibration at frequencies lower than 25 Hz whereas the VPAD-based weighting generally emphasizes the resonant responses of the finger. Our analysis indicated that the VPAD-based weighting was fairly consistent with the finger surface vibration transmissibility at frequencies greater than the first resonance, suggesting that the finger surface transmissibility may be used as an alternative frequency weighting for assessing the finger vibration exposure. The proposed method provides a practical and efficient tool to simulate the detailed biodynamic responses of a complex biological system to vibration.

Wu, John Z.; Dong, Ren G.; Welcome, Daniel E.; Xu, Xueyan S.

2010-12-01

235

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

236

Output power enhancement of optical pumped gas waveguide terahertz laser by promoting vibrational de-excitation  

NASA Astrophysics Data System (ADS)

Based on rate equation and vibration relaxation theory, the paper analyze theoretically the enhancement of THz laser output power due to vibration de-excite rate of the active gas considering buffer gas ratio and waveguide core diameter. The results show that the method of adding 1:1 buffer gas or appropriately reducing the waveguide core diameter can improve work material saturated absorption intensity, THz laser small signal gain coefficient, THz laser output power and decrease the THz absorption of excited work material at the same time. Considering the two factors at the same time, the above results are better than those with only one factor, and the output power improved by 18%.

Zhang, Huiyun; Liu, Meng; Zhang, Yuping

2014-09-01

237

Vibrational and Electron Energy Spectrum of Double Wall Carbon Nanotubes  

NASA Astrophysics Data System (ADS)

Using Raman and photocurrent spectroscopy, we are able to distinguish between inner and outer tube features in both the vibrational and electron energy spectrums of double wall carbon nanotubes (DWNTs). DWNTs are synthesized using the ``peapod'' fabrication method. The inner hollow space of single wall nanotubes (SWNTs) is filled with C60 molecules by vapor phase reaction at 400^oC, creating nanotube peapods. Annealing the peapods at 1200^oC in high vacuum transforms the C60 molecules into the inner shell of the DWNT. Transmission electron microscopy measurements reveal that highly uniform DWNTs are formed with average outer and inner diameters of 1.4 nm and 0.9 nm, respectively. The Raman spectrum of the DWNTs contains a series of peaks not observed in the SWNTs or peapods. One of these peaks at 335 cm-1 can be attributed to the radial vibrational mode of the inner nanotube. The photocurrent spectrum of the DWNTs contains two extra peaks not observed in SWNTs. Based on the tube diameters, these are associated with the S11 and S22 transitions for the inner nanotube. Supported by the NSF ( ECS-0224114) and NASA (NCC5- 571).

Mohite, Aditya; Sumanasekera, Gamini

2005-03-01

238

Energy 101: Concentrating Solar Power  

ScienceCinema

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.

239

Energy 101: Concentrating Solar Power  

ScienceCinema

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

240

Vibrational spectroscopy of HOD in liquid D2O. I. Vibrational energy relaxation  

NASA Astrophysics Data System (ADS)

We present calculations of the vibrational lifetimes for the three fundamentals of HOD in liquid D2O. The calculations build on the work of Oxtoby and of Rey and Hynes, but also introduce some new ideas, the most important of which is a self-consistent renormalization scheme for determining the system and bath Hamiltonians for a given vibrational state of the HOD molecule. Our result for T1 for the OH stretch fundamental is 2.7 ps, which is about a factor of 3 larger than the experimental number. We suggest that including solvent vibrations may bring theory in closer agreement with experiment.

Lawrence, C. P.; Skinner, J. L.

2002-09-01

241

VIBRATING RF MEMS FOR LOW POWER WIRELESS COMMUNICATIONS  

Microsoft Academic Search

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

242

A single-magnet nonlinear piezoelectric converter for enhanced energy harvesting from random vibrations  

Microsoft Academic Search

Power harvesters from mechanical vibrations are commonly linear mechanical resonators that are most efficient when excited at resonance. Differently, under wideband vibrations, linear converters are suboptimal. A nonlinear converter is here proposed that implements nonlinearity and bistability by employing one external magnet, in order to improve conversion effectiveness while simplifying device fabrication. The converter is composed of a piezoelectric bimorph

M. Ferrari; V. Ferrari; M. Guizzetti; D. Marioli

2010-01-01

243

A single-magnet nonlinear piezoelectric converter for enhanced energy harvesting from random vibrations  

Microsoft Academic Search

Power harvesters from mechanical vibrations are commonly linear mechanical resonators that are most effective when excited at resonance. Differently, under wideband vibrations, linear converters are suboptimal. A nonlinear converter is here proposed that implements nonlinearity and bistability by employing a single external magnet, in order to improve conversion effectiveness while simplifying device fabrication. The converter is composed of a piezoelectric

M. Ferrari; M. Baù; M. Guizzetti; V. Ferrari

244

An energy harvester using piezoelectric cantilever beams undergoing coupled bending-torsion vibrations  

NASA Astrophysics Data System (ADS)

Recently, piezoelectric cantilevered beams have received considerable attention for vibration-to-electric energy conversion. Generally, researchers have investigated a classical piezoelectric cantilever beam with or without a tip mass. In this paper, we propose the use of a unimorph cantilever beam undergoing bending-torsion vibrations as a new piezoelectric energy harvester. The proposed design consists of a single piezoelectric layer and a couple of asymmetric tip masses; the latter convert part of the base excitation force into a torsion moment. This structure can be tuned to be a broader band energy harvester by adjusting the first two global natural frequencies to be relatively close to each other. We develop a distributed-parameter model of the harvester by using the Euler-beam theory and Hamilton's principle, thereby obtaining the governing equations of motion and associated boundary conditions. Then, we calculate the exact eigenvalues and associated mode shapes and validate them with a finite element (FE) model. We use these mode shapes in a Galerkin procedure to develop a reduced-order model of the harvester, which we use in turn to obtain closed-form expressions for the displacement, twisting angle, voltage output, and harvested electrical power. These expressions are used to conduct a parametric study for the dynamics of the system to determine the appropriate set of geometric properties that maximizes the harvested electrical power. The results show that, as the asymmetry is increased, the harvester's performance improves. We found a 30% increase in the harvested power with this design compared to the case of beams undergoing bending only. We also show that the locations of the two masses can be chosen to bring the lowest two global natural frequencies closer to each other, thereby allowing the harvesting of electrical power from multi-frequency excitations.

Abdelkefi, A.; Najar, F.; Nayfeh, A. H.; Ben Ayed, S.

2011-11-01

245

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

246

Fluctuating energy level Landau-Teller theory: application to the vibrational energy relaxation of liquid methanol.  

PubMed

State-to-state vibrational energy relaxation (VER) rates of the OH-stretch fundamental to select vibrational modes of liquid methanol are presented. The rates are calculated via a modified, fluctuating Landau-Teller (FLT) theory approach, which allow for dynamical vibrational energy level shifts. These rates are then compared to previously published results from Gulmen and Sibert [J. Phys. Chem. A 2004, 108, 2389] for the traditional Landau-Teller (LT) method as well as results calculated through time-dependent perturbation theory (TD), which naturally allow for the fluctuation. For the first time, this method is applied to a polyatomic molecular system, and the FLT theory greatly reduces the discrepancy between the LT and TD results or, at a minimum, is comparable to the LT approach with very little additional computational cost. PMID:16833910

Gulmen, Tolga S; Sibert, Edwin L

2005-07-01

247

Single pulse laser excitation of structural vibration using power densities below the surface ablation threshold  

NASA Astrophysics Data System (ADS)

This paper describes sub-ablation optical excitation of flexural vibration in cantilevers and a suspended truck-wheel rim by using a single 600?s, Nd:glass laser pulse with energies between 1J and 40J. The excitation is consistent with the photothermal production of a localized thermoelastic bending moment at the site of the laser irradiation. This method of excitation has been combined with fibre optic sensing and modal analysis of the resulting vibrations to provide a practical method of remotely measuring the structural properties upon which the frequencies of vibration depend. The modal frequencies of slot-damaged cantilevers are presented to demonstrate the possible application of this non-contact measurement technique for non-destructive testing.

Philp, W. R.; Booth, D. J.; Perry, N. D.

1995-08-01

248

Measurements of mechanical vibrations at magnetic cores of power transformers with fiber-optic interferometric intrinsic sensor  

Microsoft Academic Search

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

249

Investigation of effect of reduction of valve friction in a power control system by use of a vibrator  

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

250

Influence of Fo?rster-type energy transfer on the vibrational relaxation of anionic hydration shells.  

PubMed

We study the influence of Fo?rster energy transfer on the vibrational relaxation dynamics of anionic hydration shells by performing time-resolved mid-infrared spectroscopy on the OH-stretch vibration of water molecules in aqueous solutions of sodium iodide. We observe that the Fo?rster energy transfer leads to a pronounced acceleration of the vibrational relaxation. We describe the observed dynamics with a model in which we include the Fo?rster vibrational energy transfer between the different hydroxyl groups in solution. With this model we can quantitatively describe the experimental data over a wide range of isotopic compositions and salt concentrations. Our results show that resonant energy transfer is an efficient mechanism assisting in the vibrational relaxation of anionic hydration shells. PMID:23901991

Lotze, Stephan; Bakker, Huib J

2013-07-28

251

Parametric resonance for vibration energy harvesting with design techniques to passively reduce the initiation threshold amplitude  

NASA Astrophysics Data System (ADS)

A vibration energy harvester designed to access parametric resonance can potentially outperform the conventional direct resonant approach in terms of power output achievable given the same drive acceleration. Although linear damping does not limit the resonant growth of parametric resonance, a damping dependent initiation threshold amplitude exists and limits its onset. Design approaches have been explored in this paper to passively overcome this limitation in order to practically realize and exploit the potential advantages. Two distinct design routes have been explored, namely an intrinsically lower threshold through a pendulum-lever configuration and amplification of base excitation fed into the parametric resonator through a cantilever-initial-spring configuration. Experimental results of the parametric resonant harvesters with these additional enabling designs demonstrated an initiation threshold up to an order of magnitude lower than otherwise, while attaining a much higher power peak than direct resonance.

Jia, Yu; Yan, Jize; Soga, Kenichi; Seshia, Ashwin A.

2014-06-01

252

Electron energy distributions, vibrational population distributions, and negative-ion concentrations in hydrogen discharges  

SciTech Connect

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

253

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

254

Rotational and Vibrational Kinetic Energies Should be Included in Mass-Energy Calculations  

NASA Astrophysics Data System (ADS)

Conversion of mass to energy involves more than rest mass. At the subatomic, nuclear, atomic and molecular levels there are rotational, spin and vibratory kinetic energies although small may account for some discrepancies between theory and experiment. In pair annhilation spin and vibratory kinetic energies should be included in calculations. Thus, [ E0= 2m0c^2 + .5I 2?rp+ .52?re+ (n + 1/2) ?vp+ (n + 1/2) ?ve+ 1/2mv^2p+ 1/2mv^2e] if the positron and electron are going slowly. The ?r and the ?v are the rotational angular velocity iand vibrational angular frequency. The mass energy equation for a nucleus and a molecule is therefore [E0= m0c^2 +1/2I?r^2 + (n +1/2)?v+ 1/2mv^2]. On a universal scale planets, stars, galaxies and galactic groups will have rotational Orbital and vibrational factors which should be included in any mass-energy conversions. Some of the energy attributed to binding energy on a nuclear level may actually be vibrational and rotational kinetic energy.

Brekke, Stewart

2007-03-01

255

A Hair-cell Structure based Piezoelectric Energy Harvester Operating under Three Dimensional Arbitrary Vibrations  

NASA Astrophysics Data System (ADS)

A hair-cell structure based piezoelectric energy harvester was newly developed to effectively scavenge three-dimensional vibrations. The cantilever of the proposed energy harvester, called a hair-cell structure, is deliberately elongated and curled so that it oscillates with decent displacement under not only vertically induced vibrations, but also under longitudinally and horizontally induced vibrations. The proposed energy harvester is comprised of an elongated and curled piezoelectric cantilever and a proof mass with high aspect ratio at the free end of the cantilever. The fabricated device generated the peak output voltage of 15 mV under vertically induced vibrations with an acceleration of 50 m/s2 at its resonance frequency of 116 Hz. Furthermore, it also generated the peak output voltage of 33 mV and 10 mV under longitudinally and horizontally induced vibrations, respectively.

Park, H.; Na, Y.; Park, J.; Park, J. Y.

2013-12-01

256

Vibrational Energy Transfer in HF/DF - CO2 Chemical Laser Systems.  

National Technical Information Service (NTIS)

The experimental method of laser induced vibrational fluorescence has been used to measure the overall rate, k(12), with which the (001) vibrational energy level of CO2 in the lowest electronic state is deactivated through collisions with DF and HF in the...

R. A. McFarlane G. J. Wolga

1971-01-01

257

Uncertainties in scaling factors for ab initio vibrational zero-point energies  

Microsoft Academic Search

Vibrational zero-point energies (ZPEs) determined from ab initio calculations are often scaled by empirical factors. An empirical scaling factor partially compensates for the effects arising from vibrational anharmonicity and incomplete treatment of electron correlation. These effects are not random but are systematic. We report scaling factors for 32 combinations of theory and basis set, intended for predicting ZPEs from computed

Karl K. Irikura; Russell D. Johnson; Raghu N. Kacker; Rüdiger Kessel

2009-01-01

258

On Developing New Statistical Energy Methods for the Analysis of Vibration Transmission in Complex Vehicle Structures  

Microsoft Academic Search

This paper presents an overview of research being conducted on vibration transmission in complex vehicle structures. Complex structures are assemblages of coupled component systems. Random parameter uncertainties in such structures can dramatically affect the high- to mid-frequency dynamics, mandating a statistical analysis. New statistical energy methods for predicting vibration transmission are explored by relaxing assumptions which limit the applications of

Christophe Pierre; Matthew P. Castanier; Sung Bae Choi

1997-01-01

259

Power and energy  

Microsoft Academic Search

The design and manufacture of electric power equipment, the one electrotechnology in which Europe could gain worldwide dominance by the end of the century, is examined. All three power-equipment categories-generation, transmission, and distribution-are involved. Europeans already lead in the production of extra-high-voltage (EHV) circuit breakers, high-voltage, direct-current (HVDC) equipment, and hydroelectric turbines. More recently, they have entered world markets for

G. Zorpette

1990-01-01

260

Power absorbed during whole-body fore-and-aft vibration: Effects of sitting posture, backrest, and footrest  

NASA Astrophysics Data System (ADS)

Although the discomfort or injury associated with whole-body vibration cannot be predicted directly from the power absorbed during exposure to vibration, the absorbed power may contribute to understanding of the biodynamics involved in such responses. From measurements of force and acceleration at the seat, the feet, and the backrest, the power absorbed at these three locations was calculated for subjects sitting in four postures (feet hanging, maximum thigh contact, average thigh contact, and minimum thigh contact) both with and without a rigid vertical backrest while exposed to four magnitudes (0.125, 0.25, 0.625, and 1.25 m s -2 rms) of random fore-and-aft vibration. The power absorbed by the body at the supporting seat surface when there was no backrest showed a peak around 1 Hz and another peak between 3 and 4 Hz. Supporting the back with the backrest decreased the power absorbed at the seat at low frequencies but increased the power absorbed at high frequencies. Foot support influenced both the magnitude and the frequency of the peaks in the absorbed power spectra as well as the total absorbed power. The measurements of absorbed power are consistent with backrests being beneficial during exposure to low frequency fore-and-aft vibration but detrimental with high frequency fore-and-aft vibration.

Nawayseh, Naser; Griffin, Michael J.

2012-01-01

261

A hybrid electromagnetic energy harvesting device for low frequency vibration  

NASA Astrophysics Data System (ADS)

An electromagnetic energy harvesting device, which converts a translational base motion into a rotational motion by using a rigid bar having a moving mass pivoted on a hinged point with a power spring, has been recently developed for use of civil engineering structures having low natural frequencies. The device utilizes the relative motion between moving permanent magnets and a fixed solenoid coil in order to harvest electrical power. In this study, the performance of the device is enhanced by introducing a rotational-type generator at a hinged point. In addition, a mechanical stopper, which makes use of an auxiliary energy harvesting part to further improve the efficiency, is incorporated into the device. The effectiveness of the proposed hybrid energy harvesting device based on electromagnetic mechanism is verified through a series of laboratory tests.

Jung, Hyung-Jo; Kim, In-Ho; Min, Dong Yi; Sim, Sung-Han; Koo, Jeong-Hoi

2013-04-01

262

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

PubMed

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

263

Effects of vibration and shock on the performance of gas-bearing space-power Brayton cycle turbomachinery. Part 3: Sinusoidal and random vibration data reduction and evaluation, and random vibration probability analysis  

NASA Technical Reports Server (NTRS)

The random vibration response of a gas bearing rotor support system has been experimentally and analytically investigated in the amplitude and frequency domains. The NASA Brayton Rotating Unit (BRU), a 36,000 rpm, 10 KWe turbogenerator had previously been subjected in the laboratory to external random vibrations, and the response data recorded on magnetic tape. This data has now been experimentally analyzed for amplitude distribution and magnetic tape. This data has now been experimentally analyzed for amplitude distribution and frequency content. The results of the power spectral density analysis indicate strong vibration responses for the major rotor-bearing system components at frequencies which correspond closely to their resonant frequencies obtained under periodic vibration testing. The results of amplitude analysis indicate an increasing shift towards non-Gaussian distributions as the input level of external vibrations is raised. Analysis of axial random vibration response of the BRU was performed by using a linear three-mass model. Power spectral densities, the root-mean-square value of the thrust bearing surface contact were calculated for specified input random excitation.

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

1973-01-01

264

[Vibrational levels and dissociation energies of diatomic systems using algebraic method].  

PubMed

The fixed order in the algebraic method (AM) suggested by Sun et al. is changed to be a flexible one in the vibrational energy expansion because the order of diatomic potential energy expansion may not be a constant. The AM with a flexible order was used to tackle the possible "butterfly effect" that may be encountered in spectroscopic computations, and to study the full vibrational levels {E(v)} and the dissociation energies D(e) for N2 - a'(1) sigma(u)(-), Li2(+) - 2 2sigma(g)(+), 4HeD(+) - X 1sigma(-) and 39K 85Rb- (2) 3sigma(+) electronic systems. The results reproduced all known experimental vibrational energies, and predicted correct dissociation energies and all unknown high-lying levels that may not be given if one uses original AM. The calculations showed that the modified AM can be extended to study the full vibrational spectra for many more diatomic systems. PMID:22497117

Zhang, Yi; Sun, Wei-guo; Fu, Jia; Fan, Qun-chao; Feng, Hao; Li, Hui-dong

2012-01-01

265

Single pulse laser excitation of structural vibration using power densities below the surface ablation threshold  

Microsoft Academic Search

This paper describes sub-ablation optical excitation of flexural vibration in cantilevers and a suspended truck-wheel rim by using a single 600?s, Nd:glass laser pulse with energies between 1J and 40J. The excitation is consistent with the photothermal production of a localized thermoelastic bending moment at the site of the laser irradiation. This method of excitation has been combined with fibre

W. R. Philp; D. J. Booth; N. D. Perry

1995-01-01

266

Power Technologies Energy Data Book  

DOE Data Explorer

In 2002, the Strategic Energy Analysis Center of the National Renewable Energy Laboratory (NREL) developed the first version of the Power Technologies Energy Data Book for DOE's Office of Power Technologies. The main purpose of the data book is to compile, in one central document, a comprehensive set of data about power technologies from diverse sources. The need for policy makers and analysts to be well-informed about power technologies suggests the need for a publication that includes a diverse, yet focused, set of data about power technologies. The latest edition of the PTEDB features Geographic Information System (GIS) maps. One set of maps shows the natural resource (biomass, geothermal, solar, and wind) overlaid with the national transmission grid and the major electricity load centers. The other set of maps shows the current installed capacity (biomass, geothermal, concentrating solar power, and wind), as well as a bar chart indicating the historic trend of generating capacity for the state. The book is organized into 13 chapters: • 1 - Introduction • 2 - Technology Profiles • 3 - Electricity Restructuring • 4 - Forecasts/Comparisons • 5 - Electricity Supply • 6 - Electricity Capability • 7 - Electricity Generation • 8 - Electricity Demand • 9 - Prices • 10 - Economic Indicators • 11 - Environmental Indicators • 12 - Conversion Factors • 13 - Geographic Information System (GIS) Maps This fourth edition of the Power Technologies Energy Data Book, as well as previous editions, are available on the Internet at http://www.nrel.gov/analysis/power_databook/. The PTEDB may be downloaded as a single PDF file, individual chapters, or table PDF files. Selected data also is available as Excel spreadsheets. The Web site also features energy-conversion calculators and features links to the Transportation Energy Data Book and Buildings Energy Data Book. [copied from http://www.nrel.gov/analysis/power_databook/chapter1.html

Aabakken, J°rn [Editor

267

Reactive Power from Distributed Energy  

SciTech Connect

Distributed energy is an attractive option for solving reactive power and distribution system voltage problems because of its proximity to load. But the cost of retrofitting DE devices to absorb or produce reactive power needs to be reduced. There also needs to be a market mechanism in place for ISOs, RTOs, and transmission operators to procure reactive power from the customer side of the meter where DE usually resides. (author)

Kueck, John; Kirby, Brendan; Rizy, Tom; Li, Fangxing; Fall, Ndeye

2006-12-15

268

Analysis and synthesis of self-powered linear structural control with imperfect energy storage  

Microsoft Academic Search

Self-powered vibration control systems are characterized by a distributed network of regenerative force actuators, which are interfaced with a common power bus. Also connected to the power bus is an energy-storing subsystem, such as a supercapacitor, flywheel, or battery. The entire system is controlled using switch-mode power electronics, and the only power required for system operation is that necessary to

J. T. Scruggs

2009-01-01

269

Photovoltaic energy in power market  

Microsoft Academic Search

Photovoltaic (PV) penetration in the grid connected power system has been growing. Currently, PV electricity is usually directly sold back to the energy supplier at a fixed price nd subsidy. However, subsidies should always be a temporary policy, and will eventually be terminated. A question is raised whether grid-connected PV generation will be more beneficial by making biddings in power

D. T. Ho; J. Frunt; J. M. A. Myrzik

2009-01-01

270

Energy discharge heater power supply  

SciTech Connect

The heater power supply is intended to supply capacitively stored,energy to embedded heater strips in cryo magnets. The amount of energy can be controlled by setting different charge different capacitor values. Two chassis' can be operated in series or interlocks are provided. The charge voltage, number of capacitors pulse can be monitored. There and dual channel has two discharge supplies in one chassis. This report reviews the characteristics of this power supply further.

Jaskierny, W.

1992-11-01

271

Vibration transmission through rolling element bearings. IV - Statistical energy analysis  

NASA Technical Reports Server (NTRS)

A theoretical broadband coupling-loss factor is developed analytically for use in the statistical energy analysis (SEA) of a shaft-bearing-plate system. The procedure is based on the solution of the boundary-value problem at the plate-bearing interface and incorporates a bearing-stiffness matrix developed by the authors. Three examples are utilized to illustrate the SEA incorporating the coupling-loss factor including: (1) a shaft-bearing-plate system; (2) a plate-cantilevered beam; and (3) a circular-shaft-bearing plate. The coupling-loss factor in the case of the thin plate-cantilevered beam is found to be more accurate than that developed by Lyon and Eichler (1964). The coupling-loss factor is described for the bearing system and extended to describe the mean-square vibratory response of a rectangular plate. The proposed techniques are of interest to the study of vibration and noise in rotating machinery such as gearboxes.

Lim, T. C.; Singh, R.

1992-01-01

272

Optimization of passive piezoelectric vibration shunt control based on strain energy transfer and online frequency detection  

NASA Astrophysics Data System (ADS)

Passive vibration shunt control using piezoelectric material (PZT) and an electrical network can remove considerable amount of vibration energy from flexible structures. In this paper, an analytical study of parallel passive resistor-inductor (R-L) piezoelectric vibration shunt control on a beam structure by using the Hamilton's principle, Galerkin's method is presented. However, the efficiency of such vibration control method relies on the optimization of vibration energy transfer between a structure and piezoelectric material. In this paper, the strain energy transfer within the composite material, which is made of two layers of different materials, is analyzed. It indicates that neutral axis of the composite material has some influence on the optimization of the strain energy transfer between the structure and PZT. The passive vibration shunt control is sensitive to frequency shift of structures. However, in reality, the natural frequencies of flexible structures often vary somewhat due to environment change, such as boundary conditions, temperature variation, etc. The effectiveness of the vibration shunt control will be significantly reduced when the frequency of the shunt circuit does not match the natural frequency of the structure. In this paper, a method of estimating the resonant frequencies of structures using adaptive IIR notch filter is presented. With online frequency detection, the inductor value is possible to be adjusted in real time by some kind of controllable capacitors and resistors to track the frequency change of structures.

Cao, Jia Long; John, Sabu; Molyneaux, Tom

2006-04-01

273

Investigation of geometries of bistable piezoelectric-laminate plates for vibration-based energy harvesting  

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

274

Intramolecular vibrational energy redistribution and intermolecular energy transfer in the (d, d) excited state of nickel octaethylporphyrin  

Microsoft Academic Search

The formation of a vibrationally excited photoproduct of nickel octaethylporphyrin (NiOEP) upon (pi, pi*) excitation and its subsequent vibrational energy relaxation were monitored by picosecond time-resolved resonance Raman spectroscopy. Stokes Raman bands due to the photoproduct instantaneously appeared upon the photoexcitation. Their intensities decayed with a time constant of ~300 ps, which indicates electronic relaxation from the (d, d) excited

Yasuhisa Mizutani; Yuki Uesugi; Teizo Kitagawa

1999-01-01

275

Power independent ignition energy measurements  

SciTech Connect

A portion of the electrical energy supplied to hot-wire ignitable materials is dissipated, largely through thermal conduction, to the unignited portion of the charge and to the containment and igniter system. The remainder of the energy deposited by the igniter wire raises the mass of material required for sustained reaction to the critical reaction temperature. The amount of energy dissipated is a direct function of the time from first application of power, to ignition. Time to ignition can be controlled by altering firing pulse power. Integration of the power pulse from start until ignition yields the ignition energy. Repetition of this procedure at different power levels permits one to plot energy versus firing time. Since conduction losses are time dependent, extrapolation of the resulting curve to zero time yields an ignition energy value that is independent of losses due to thermal conduction. A key to the success of the procedure is accurate observation of ignition time. It was found that the reaction energy released at ignition causes a discernible deflection in the firing current record. By comparison of light emission and current traces, it was found that the onset of deflagration occurs at the inflection point of the current trace deflection. This procedure has been successfully applied to hot pressed thermite samples, yielding ignition energies that are in qualitative agreement with the expected sensitivities of the samples.

Mohler, J.

1980-01-01

276

An experimentally validated double-mass piezoelectric cantilever model for broadband vibration–based energy harvesting  

Microsoft Academic Search

Narrow bandwidth is the major challenge to today’s vibration-based energy harvesters. Compared with other broadband approaches that involve moving parts and control electronics, a double-mass piezoelectric cantilever beam provides a simple and reliable solution to widen the effective bandwidth as a vibration energy harvester. In this article, a continuum model of a double-mass lead zirconate titanate cantilever subject to sinusoidal

Qing Ou; XiaoQi Chen; Stefanie Gutschmidt; Alan Wood; Nigel Leigh; Andres F Arrieta

2012-01-01

277

An energy harvester using piezoelectric cantilever beams undergoing coupled bending-torsion vibrations  

Microsoft Academic Search

Recently, piezoelectric cantilevered beams have received considerable attention for vibration-to-electric energy conversion. Generally, researchers have investigated a classical piezoelectric cantilever beam with or without a tip mass. In this paper, we propose the use of a unimorph cantilever beam undergoing bending-torsion vibrations as a new piezoelectric energy harvester. The proposed design consists of a single piezoelectric layer and a couple

A. Abdelkefi; F. Najar; A. H. Nayfeh; S. Ben Ayed

2011-01-01

278

Development of new vibration energy flow analysis software and its applications to vehicle systems  

Microsoft Academic Search

The Energy flow analysis (EFA) offers very promising results in predicting the noise and vibration responses of system structures in medium-to-high frequency ranges. We have developed the Energy flow finite element method (EFFEM) based software, EFADSC++ R4, for the vibration analysis. The software can analyze the system structures composed of beam, plate, spring-damper, rigid body elements and many other components

D.-J. Kim; S.-Y. Hong; Y.-H. Park

2005-01-01

279

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

280

Effect of material constants on power output in piezoelectric vibration-based generators.  

PubMed

A possible power output estimation based on material constants in piezoelectric vibration-based generators is proposed. A modified equivalent circuit model of the generator was built and was validated by the measurement results in the generator fabricated using potassium sodium niobate-based and lead zirconate titanate (PZT) ceramics. Subsequently, generators with the same structure using other PZT-based and bismuth-layered structure ferroelectrics ceramics were fabricated and tested. The power outputs of these generators were expressed as a linear functions of the term composed of electromechanical coupling coefficients k(sys)(2) and mechanical quality factors Q*(m) of the generator. The relationship between device constants (k(sys)(2) and Q*(m)) and material constants (k(31)(2) and Q(m)) was clarified. Estimation of the power output using material constants is demonstrated and the appropriate piezoelectric material for the generator is suggested. PMID:21937317

Takeda, Hiroaki; Mihara, Kensuke; Yoshimura, Tomohiro; Hoshina, Takuya; Tsurumi, Takaaki

2011-09-01

281

A study of several vortex-induced vibration techniques for piezoelectric wind energy harvesting  

NASA Astrophysics Data System (ADS)

This paper discusses a preliminary study on harnessing energy from piezoelectric transducers by using bluff body and vortex-induced vibration phenomena. Structures like bridges and buildings tend to deform and crack due to chaotic fluid-structure interactions. The rapid variation of pressure and velocity can be tapped and used to power structural health monitoring systems. The proposed device is a miniature, scalable wind harvesting device. The configuration consists of a bluff body with a flexible piezoelectric cantilever attached to the trailing edge. Tests are run for different characteristic dimensions or shapes for the bluff body and optimized for maximum power over a wide range of flow velocities. The main motive here is to seek a higher synchronized region of frequencies for the oscillation amplitudes. The multi-physics software package COMSOL is used to vary the design parameters to optimize the configuration and to identify the significant parameters in the design. The simulation results obtained show a wider lock-in bandwidth and higher average power for the cylindrical bluff body compared to the other two bluff body shapes investigated, the greatest average power being 0.35mW at a Reynolds number of 900, beam length of 0.04m, and bluff body diameter of 0.02m.

Sivadas, Vishak; Wickenheiser, Adam M.

2011-03-01

282

Electric-energy generation using variable-capacitive resonator for power-free LSI: efficiency analysis and fundamental experiment  

Microsoft Academic Search

A power generator based on a vibration-to-electric energy converter using a variable-resonating capacitor is experimentally demonstrated. The generator consists of a complete system with a mechanical-variable capacitor, a charge-transporting LC tank circuit and an externally powered timing-capture controller. A practical design methodology to maximize the efficiency of the vibration-to-electric energy generation system is also described. The efficiency of the generator

Masayuki Miyazaki; Hidetoshi Tanaka; Goichi Ono; Tomohiro Nagano; Norio Ohkubo; Takayuki Kawahara; Kazuo Yano

2003-01-01

283

Vibrational and Rotational Energy Distributions in a Hot Cl2 Molecular Beam  

NASA Astrophysics Data System (ADS)

Vibrational and rotational energy distributions of a hot Cl2 (Cl2*) molecular beam, which is used for a semiconductor device etching process, is studied by a laser-induced fluorescence method. The Cl2* beam is produced by free jet expansion of a Cl2 gas heated in a quartz furnace. It is found that the hot molecular beam is a transition flow between a continuum free jet and an effusive flow. The vibrational and rotational energy distributions can be described by Boltzmann functions of well-defined temperatures. The vibrational temperature is rather close to the furnace exit temperature, while the rotational temperature is cooled to 150-250 K during the isentropic free expansion. These results show that furnace exit temperature is crucial to the production of a highly reactive hot molecular beam of large vibrational energy.

Hiraoka, Susumu; Suzuki, Keizo; Nishimatsu, Shigeru

1989-07-01

284

General model with experimental validation of electrical resonant frequency tuning of electromagnetic vibration energy harvesters  

NASA Astrophysics Data System (ADS)

This paper presents a general model and its experimental validation for electrically tunable electromagnetic energy harvesters. Electrical tuning relies on the adjustment of the electrical load so that the maximum output power of the energy harvester occurs at a frequency which is different from the mechanical resonant frequency of the energy harvester. Theoretical analysis shows that for this approach to be feasible the electromagnetic vibration energy harvester’s coupling factor must be maximized so that its resonant frequency can be tuned with the minimum decrease of output power. Two different-sized electromagnetic energy harvesters were built and tested to validate the model. Experimentally, the micro-scale energy harvester has a coupling factor of 0.0035 and an untuned resonant frequency of 70.05 Hz. When excited at 30 mg, it was tuned by 0.23 Hz by changing its capacitive load from 0 to 4000 nF its effective tuning range is 0.15 Hz for a capacitive load variation from 0 to 1500 nF. The macro-scale energy harvester has a coupling factor of 552.25 and an untuned resonant frequency of 95.1 Hz and 95.5 Hz when excited at 10 mg and 25 mg, respectively. When excited at 10 mg, it was tuned by 3.8 Hz by changing its capacitive load from 0 to 1400 nF it has an effective tuning range of 3.5 Hz for a capacitive load variation from 0 to 1200 nF. When excited at 25 mg, its resonant frequency was tuned by 4.2 Hz by changing its capacitive load from 0 to 1400 nF it has an effective tuning range of about 5 Hz. Experimental results were found to agree with the theoretical analysis to within 10%.

Zhu, Dibin; Roberts, Stephen; Mouille, Thomas; Tudor, Michael J.; Beeby, Stephen P.

2012-10-01

285

The effects of whole-body vibration on the wingate test for anaerobic power when applying individualized frequencies.  

PubMed

Surowiec, RK, Wang, H, Nagelkirk, PR, Frame, JW, and Dickin, DC. The effects of whole-body vibration on the Wingate test for anaerobic power when applying individualized frequencies. J Strength Cond Res 28(7): 2035-2041, 2014-Recently, individualized frequency (I-Freq) has been introduced with the notion that athletes may elicit a greater reflex response at differing levels (Hz) of vibration. The aim of the study was to evaluate acute whole-body vibration as a feasible intervention to increase power in trained cyclists and evaluate the efficacy of using I-Freq as an alternative to 30Hz, a common frequency seen in the literature. Twelve highly trained, competitive male cyclists (age, 29.9 ± 10.0 years; body height, 175.4 ± 7.8 cm; body mass, 77.3 ± 13.9 kg) participated in the study. A Wingate test for anaerobic power was administered on 3 occasions: following a control of no vibration, 30 Hz, or I-freq. Measures of peak power, average power (AP), and the rate of fatigue were recorded and compared with the vibration conditions using separate repeated measures analysis of variance. Peak power, AP, and the rate of fatigue were not significantly impacted by either the 30 Hz or I-Freq vibration interventions (p > 0.05). Given the trained status of the individuals in this study, the ability to elicit an acute response may have been muted. Future studies should further refine the vibration parameters used and assess changes in untrained or recreationally trained populations. PMID:24378660

Surowiec, Rachel K; Wang, Henry; Nagelkirk, Paul R; Frame, Jeffrey W; Dickin, D Clark

2014-07-01

286

Large scale variational calculations on the vibrational level structure and vibrational mixing in S0 HDCO up to very high excitation energies  

NASA Astrophysics Data System (ADS)

We perform converged high precision variational calculations to determine the exact energies of all vibrational states in S0 HDCO, extending up to 10 000 cm-1 of vibrational excitation energy. We also explore the resonances and intermode couplings in this energy range. We compare the calculated level structure to the recently measured frequencies by Ellsworth et al. [K.K. Ellsworth, B.D. Lajiness, J.P. Lajiness and W.F. Polik, J. Mol. Spectrosc. 252 (2008) 205] in order to check their assignments and further clarify the vibrational mixing pattern and vibrational resonances in HDCO, that are very different from the other more symmetric formaldehyde species H2CO and D2CO. For the calculations we use our specific vibrational method (recently employed for extensive vibrational studies on H2CO and D2CO), consisting of a combination of a search/selection algorithm and a Lanczos iteration procedure and based on the Martin, Lee, Taylor potential energy surface for formaldehyde, allowing to extend the calculations up to very high vibrational excitation energies.

Rashev, Svetoslav; Moule, David C.

2013-04-01

287

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

288

Development of a simplified, mass producible hybridized ambient, low frequency, low intensity vibration energy scavenger (half-lives)  

NASA Astrophysics Data System (ADS)

Scavenging energy from environmental sources is an active area of research to enable remote sensing and microsystems applications. Furthermore, as energy demands soar, there is a significant need to explore new sources and curb waste. Vibration energy scavenging is one environmental source for remote applications and a candidate for recouping energy wasted by mechanical sources that can be harnessed to monitor and optimize operation of critical infrastructure (e.g. Smart Grid). Current vibration scavengers are limited by volume and ancillary requirements for operation such as control circuitry overhead and battery sources. This dissertation, for the first time, reports a mass producible hybrid energy scavenger system that employs both piezoelectric and electrostatic transduction on a common MEMS device. The piezoelectric component provides an inherent feedback signal and pre-charge source that enables electrostatic scavenging operation while the electrostatic device provides the proof mass that enables low frequency operation. The piezoelectric beam forms the spring of the resonant mass-spring transducer for converting vibration excitation into an AC electrical output. A serially poled, composite shim, piezoelectric bimorph produces the highest output rectified voltage of over 3.3V and power output of 145muW using ¼ g vibration acceleration at 120Hz. Considering solely the volume of the piezoelectric beam and tungsten proof mass, the volume is 0.054cm3, resulting in a power density of 2.68mW/cm3. Incorporation of a simple parallel plate structure that provides the proof mass for low frequency resonant operation in addition to cogeneration via electrostatic energy scavenging provides a 19.82 to 35.29 percent increase in voltage beyond the piezoelectric generated DC rails. This corresponds to approximately 2.1nW additional power from the electrostatic scavenger component and demonstrates the first instance of hybrid energy scavenging using both piezoelectric and synchronous electrostatic transduction. Furthermore, it provides a complete system architecture and development platform for additional enhancements that will enable in excess of 100muW additional power from the electrostatic scavenger.

Khbeis, Michael Tawfik

289

Power and energy for posterity  

NASA Technical Reports Server (NTRS)

The use of sophisticated space energy generation and storage systems to benefit the general public was examined. The utilization of these systems for pollution-free generation of energy to satisfy mankind's future electrical, thermal, and propulsion needs was of primary concern. Ground, air, and space transportation; commercial, peaking, and emergency electrical power; and metropolitan and unit thermal energy requirements were considered. Each type of energy system was first analyzed in terms of its utility in satisfying the requirement, and then its potential in reducing the air, noise, thermal, water, and nuclear pollution from future electrical and thermal systems was determined.

Barthelemy, R. F.; Cooper, R. F.

1972-01-01

290

Vibration energy absorption (VEA) in human fingers-hand-arm system.  

PubMed

A methodology for measuring the vibration energy absorbed into the fingers and the palm exposed to vibration is proposed to study the distribution of the vibration energy absorption (VEA) in the fingers-hand-arm system and to explore its potential association with vibration-induced white finger (VWF). The study involved 12 adult male subjects, constant-velocity sinusoidal excitations at 10 different discrete frequencies in the range of 16-1000 Hz, and four different hand-handle coupling conditions (finger pull-only, hand grip-only, palm push-only, and combined grip and push). The results of the study suggest that the VEA into the fingers is considerably less than that into the palm at low frequencies (< or = 25 Hz). They are, however, comparable under the excitations in the 250-1000 Hz frequency range. The finger VEA at high frequencies (> or = 100 Hz) is practically independent of the hand-handle coupling condition. The coupling conditions affect the VEA into the fingers and the palm very differently. The finger VEA results suggest that the ISO standardized frequency weighting (ISO 5349-1, 2001) may underestimate the effect of high frequency vibration on vibration-induced finger disorders. The proposed method may provide new opportunities to examine VEA and its association with VWF and other types of vibration-induced disorders in the hand-arm system. PMID:15234684

Dong, R G; Schopper, A W; McDowell, T W; Welcome, D E; Wu, J Z; Smutz, W P; Warren, C; Rakheja, S

2004-07-01

291

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

PubMed Central

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.

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

2013-01-01

292

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

SciTech Connect

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

293

Laser double resonance measurements of vibrational energy transfer rates and mechanisms in HF(v = 2)  

Microsoft Academic Search

Overtone vibration-laser double resonance studies of HF(v = 2) yield self-relaxation rate constants for v = 2 and v = 1 of k2 = (19.8±1.0) ×10?12 cm3 molecule?1 s?1 and k1 = (1.46±0.1) ×10?12 cm3 molecule?1s?1, respectively. These experiments indicate that the fraction of HF(v = 2) molecules relaxing via vibration-to-vibration energy transfer is only 0.35±0.10, in sharp contrast to

R. A. Copeland; D. J. Pearson; Jeanne M. Robinson; F. F. Crim

1982-01-01

294

Accurate potential energy, dipole moment curves, and lifetimes of vibrational states of heteronuclear alkali dimers.  

PubMed

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(1)?(+) 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(-1) for LiNa and by no more than 114 cm(-1) for the other molecules. The discrepancies between the experimental and calculated harmonic vibrational frequencies are less than 1.7 cm(-1), and the discrepancies for the anharmonic correction are less than 0.1 cm(-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. PMID:24832278

Fedorov, Dmitry A; Derevianko, Andrei; Varganov, Sergey A

2014-05-14

295

Accurate potential energy, dipole moment curves, and lifetimes of vibrational states of heteronuclear alkali dimers  

NASA Astrophysics Data System (ADS)

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 X1?+ 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-1 for LiNa and by no more than 114 cm-1 for the other molecules. The discrepancies between the experimental and calculated harmonic vibrational frequencies are less than 1.7 cm-1, and the discrepancies for the anharmonic correction are less than 0.1 cm-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.; Derevianko, Andrei; Varganov, Sergey A.

2014-05-01

296

Switching from molecular to dissociative adsorption with vibrational energy: ethylene on Ag(0 0 1)  

Microsoft Academic Search

We show that vibrational energy can be used to tune the chemisorption state of an adsorbed molecule. When dosing C2H4 with a supersonic molecular beam on Ag(001) we demonstrate by vibrational spectroscopy that, with increasing nozzle temperature, TN, firstly no stable adsorption occurs, then a ?-bonded configuration is populated, switching finally to a more strongly, undissociated, di-?-bonded state. Direct dissociation

L. Vattuone; L. Savio; U. Valbusa; M. Rocca

2000-01-01

297

Vibrational-Energy Redistribution in Single-Atom Manipulation by Scanning Tunneling Microscope  

Microsoft Academic Search

A pairwise phenomenon is observed when we attempt to extract asingle H atom from a monohydride Si(100)-2×1:H surface. This is attributed to the final vibrational excitation induced by the tunneling electrons and the desorption of two H atoms on one Si dimer simultaneously as an H2 molecule. The pair effect is thought to be direct evidence of vibrational-energy transfer on

Qiang Shi; Dehuan Huang; Qingshi Zhu

1999-01-01

298

The design, fabrication and evaluation of a MEMS PZT cantilever with an integrated Si proof mass for vibration energy harvesting  

NASA Astrophysics Data System (ADS)

A microelectromechanical system (MEMS) piezoelectric energy harvesting device, a unimorph PZT cantilever with an integrated Si proof mass, was designed for low vibration frequency and high vibration amplitude environment. Pt/PZT/Pt/Ti/SiO2 multilayered films were deposited on a Si substrate and then the cantilever was patterned and released by inductively coupled plasma reactive ion etching. The fabricated device, with a beam dimension of about 4.800 mm × 0.400 mm × 0.036 mm and an integrated Si mass dimension of about 1.360 mm × 0.940 mm × 0.456 mm produced 160 mVpk, 2.15 ?W or 3272 ?W cm-3 with an optimal resistive load of 6 k? from 2g (g = 9.81 m s-2) acceleration at its resonant frequency of 461.15 Hz. This device was compared with other demonstrated MEMS power generators.

Shen, Dongna; Park, Jung-Hyun; Ajitsaria, Jyoti; Choe, Song-Yul; Wikle, Howard C., III; Kim, Dong-Joo

2008-05-01

299

Active Seismic Monitoring Using High-Power Moveable 40-TONS Vibration Sources in Altay-Sayn Region of Russia  

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

300

Improved energy harvesting from wideband vibrations by nonlinear piezoelectric converters  

Microsoft Academic Search

Vibration harvesters typically are linear mass-spring devices working at resonance. A different approach is here proposed based on nonlinear converters that exploit stochastic resonance with white-noise excitation. It consists of a piezoelectric beam converter coupled to permanent magnets to create a bistable system. Under proper conditions, the system bounces between two stable states in response to random excitation, which significantly

M. Ferrari; V. Ferrari; M. Guizzetti; B. Andò; S. Baglio; C. Trigona

2010-01-01

301

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

302

Demand, Energy, and Power Factor.  

National Technical Information Service (NTIS)

This paper briefly presents the results of a study of various utility rate schedules from across the United States and describes a video produced to explain some major features of these rate structures. In particular, the demand, energy and power factor s...

M. J. Gough

1994-01-01

303

Radiant energy power source structure  

SciTech Connect

This patent describes a radiant energy power source structure for providing electrical power to a vehicle utilizing radiant energy from a jet engine, the jet engine of the type having a radiant energy emitting combustion chamber formed from spaced apart inner and outer concentric elongated cylindrical liners, the combustion chamber outer liner concentrically surrounded by an elongated annular outer combustion casing. It comprises: a modified elongated annular combustion casing; a plurality of pairs of circumferentially spaced apart ribs operably attached to the elongated annular base; at least one photovoltaic cell operably situated between each pair of longitudinal ribs; a set of opposed, longitudinally extending grooves formed in the pair of ribs at a location radially spaced from the at least one photovoltaic cell; and a protective plate removable carried in the grooves.

Doellner, O.L.

1992-07-14

304

Reaction of formaldehyde cation with molecular hydrogen: Effects of collision energy and H2CO+ vibrations  

NASA Astrophysics Data System (ADS)

The effects on the title reaction of collision energy (Ecol) and five H2CO+ vibrational modes have been studied over a center-of-mass Ecol range from 0.1 to 2.3 eV. Electronic structure and Rice-Ramsperger-Kassel-Marcus calculations were used to examine properties of various complexes and transition states that might be important. Only the hydrogen abstraction (HA) product channel is observed, and despite being exoergic, HA has an appearance energy of ~0.4 eV, consistent with a transition state found in the electronic structure calculations. A precursor complex-mediated mechanism might possibly be involved at very low Ecol, but the dominant mechanism is direct over the entire Ecol range. The magnitude of the HA cross section is strongly, and mode specifically affected by H2CO+ vibrational excitation, however, vibrational energy has no effect on the appearance energy.

Liu, Jianbo; Anderson, Scott L.

2004-05-01

305

Vibrational energies of PH3 calculated variationally at the complete basis set limit.  

PubMed

The potential energy surface for the electronic ground state of PH(3) was calculated at the CCSD(T) level using aug-cc-pV(Q+d)Z and aug-cc-pVQZ basis sets for P and H, respectively, with scalar relativistic corrections included. A parametrized function was fitted through these ab initio points, and one parameter of this function was empirically adjusted. This analytical PES was employed in variational calculations of vibrational energies with the newly developed program TROVE. The convergence of the calculated vibrational energies with increasing vibrational basis set size was improved by means of an extrapolation scheme analogous to the complete basis set limit schemes used in ab initio electronic structure calculations. The resulting theoretical energy values are in excellent agreement with the available experimentally derived values. PMID:18681648

Ovsyannikov, Roman I; Thiel, Walter; Yurchenko, Sergei N; Carvajal, Miguel; Jensen, Per

2008-07-28

306

Nonequilibrium molecular-dynamics study of the vibrational energy relaxation of peptides in water  

NASA Astrophysics Data System (ADS)

A nonequilibrium description of the vibrational-energy relaxation of solvated flexible molecules such as small peptides in aqueous solution is outlined. Having in mind to employ standard biomolecular molecular-dynamics program packages, several methodological developments are introduced. To calculate the vibrational normal-mode energies for a system undergoing large-amplitude motion, an instantaneous normal-mode analysis is employed. To mimic the laser excitation of a given vibrational mode in its excited states, a computational scheme is proposed which allows us to calculate the nonequilibrium phase-space initial conditions for the solute and the solvent atoms. It is demonstrated that the vibrational relaxation dynamics sensitively depends on the accurate representation of the initially excited normal mode. In particular, effects of the quantum-mechanical zero-point energy contained by the initial state are investigated, thus elucidating the importance of quantum fluctuations. To study the validity and the performance of the method, the laser-induced amide I ?=1-->0 energy relaxation of N-methylacetamid in D2O is considered. The vibrational energy relaxation rate obtained from the nonequilibrium simulations is in qualitative agreement with experiment, whereas a Landau-Teller-type calculation underestimates the rate considerably. The virtues and problems of the nonequilibrium description are discussed in some detail.

Nguyen, Phuong H.; Stock, Gerhard

2003-12-01

307

Chromophore vibrations during isomerization of photoactive yellow protein: analysis of normal modes and energy transfer  

NASA Astrophysics Data System (ADS)

Ultrafast studies of fluorescence decay of photoactive yellow protein (PYP) and several mutants by Mataga et al. [Chem. Phys. Lett. 352 (2002) 220] reveal coherent oscillations of about 140 cm -1, attributed to largely chromophore motions, and 50 cm -1, corresponding more to protein matrix vibrations. We identify these vibrations by normal mode analysis. Vibrational modes near 130 cm -1 are relatively localized to the chromophore, consistent with interpretation of the ultrafast data. Dynamical coupling between the chromophore and protein matrix enhances twisting of the thioester group near 130 cm -1 compared to the isolated chromophore. We also compute rates of vibrational energy transfer rates in PYP and discuss its influence on the photoisomerization kinetics.

Yu, Xin; Leitner, David M.

2004-06-01

308

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

309

Spectroscopic probes of vibrationally excited molecules at chemically significant energies  

SciTech Connect

Infrared-optical double resonance is being used to study the unimolecular dissociation dynamics of hydrazoic acid (HN[sub 3]). 6[nu][sub NH] vibrational overtone excitation spectra are given for HN[sub 3]. Work was begun to determine the feasibility of extending the infrared-optical double resonance photofragment spectroscopy to small free radicals, and to be able to monitor atomic dissociation fragments via laser induced fluorescence in the VUV spectrum. 1 fig.

Rizzo, T.R.

1993-04-01

310

Energies and Vibrational Frequencies of Gaseous Alkali Halide M2X+ Ions  

Microsoft Academic Search

A potential function describing the interaction between the ions of M2X+ molecules has been developed using a model suggested by Pauling. From this potential the energies and vibrational frequencies have been calculated for these molecules. The harmonic contributions to the bending frequencies are shown to be far from negligible based on this purely ionic model. The entropy and free energy

Thomas A. Milne; Daniel Cubicciotti

1959-01-01

311

Rotation-Vibration Energies of the Pyramidal XY3 Molecular Model  

Microsoft Academic Search

Complete expressions have been derived for the rotation-vibration energies of the pyramidal XY3 molecular model in such a way as to include, through second order of approximation, all contributions to the energies arising from Coriolis interactions, anharmonicities, etc.

Wave Henry Shaffer

1941-01-01

312

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

313

An optimized self-powered switching circuit for non-linear energy harvesting with low voltage output  

Microsoft Academic Search

Harvesting energy from environmental sources has been of particular interest these last few years. Microgenerators that can power electronic systems are a solution for the conception of autonomous, wireless devices. They allow the removal of bulky and costly wiring, as well as complex maintenance and environmental issues for battery-powered systems. In particular, using piezoelectric generators for converting vibrational energy to

Mickaël Lallart; Daniel Guyomar

2008-01-01

314

Hybrid Suspension System with Skyhook Control and Energy Regeneration (Development of Self-Powered Active Suspension)  

Microsoft Academic Search

This paper presents a method of active vibration control system using regenerated vibration energy,i.e., the hybrid suspension system with active control and energy regeneration. In this system, all the energy for active control is supplied from a damper which regenerates vibration energy. In order to attain this system, less energy consumed control law and a device which can regenerate vibration

1998-01-01

315

Laser Measurement of the Nitrogen to Carbon Dioxide Vibrational Energy Transfer Time  

Microsoft Academic Search

An experiment is described in which two cavities are installed on a gasdynamic laser. From the power at the downstream cavity, an evaluation of the cross section for vibrational transfer between nitrogen and carbon dioxide can be made. The result is in agreement with other measurements.

J. Wilson

1971-01-01

316

Effect of collision energy and vibrational excitation on endothermic ion-molecule reactions  

SciTech Connect

This thesis is divided into two major parts. In the first part an experimental study of proton and deuteron transfer in H/sub 2//sup +/ + He and HD/sup +/ + He has been carried out as a function of kinetic and vibrational energy. The data gives evidence that at lower kinetic energies, the spectator stripping mechanism indeed plays an important role when H/sub 2//sup +/ or HD/sup +/ is vibrationally excited. The second half of this thesis examines the relative efficiencies between the excitation of C-C stretching vibration and collision energy on the promotion of the H atom transfer reaction of C/sub 2/H/sub 2//sup +/ + H/sub 2/ ..-->.. C/sub 2/H/sub 3//sup +/ + H.

Turner, T.P.

1984-07-01

317

Vibrational energy flow models for the Rayleigh-Love and Rayleigh-Bishop rods  

NASA Astrophysics Data System (ADS)

Energy Flow Analysis (EFA) has been developed to predict the vibrational energy density of the system structures in the medium-to-high frequency range. The elementary longitudinal wave theory is often used to describe the longitudinal vibration of a slender rod. However, for relatively large diameter rods or high frequency ranges, the elementary longitudinal wave theory is inaccurate because the lateral motions are not taken into account. In this paper, vibrational energy flow models are developed to analyze the longitudinally vibrating Rayleigh-Love rod considering the effect of lateral inertia, and the Rayleigh-Bishop rod considering the effect not only of the lateral inertia but also of the shear stiffness. The derived energy governing equations are second-order differential equations which predict the time and space averaged energy density and active intensity distributions in a rod. To verify the accuracy of the developed energy flow models, various numerical analyses are performed for a rod and coupled rods. Also, the EFA results for the Rayleigh-Love and Rayleigh-Bishop rods are compared with the analytical solutions for these models, the traditional energy flow solutions, and the analytical solutions for the classical rod.

Han, Ju-Bum; Hong, Suk-Yoon; Song, Jee-Hun; Kwon, Hyun-Wung

2014-01-01

318

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

2012-03-01

319

Efficiency of stimulation of gaseous chemical reactions by a diffracted light beam whose energy is absorbed by vibrational transitions  

Microsoft Academic Search

Laser-induced reversible chemical reaction kinetics in a gas mixture with the absorption of light energy by molecular vibrational\\u000a transitions is investigated by mathematical modeling. The influence of beam diffraction, the relaxation time of vibrational\\u000a energy into heat, and the order of vibrational transition on the structure of the region of high absorption and on the propagation\\u000a of switching waves is

O. A. Gunaze; V. A. Trofimov

1999-01-01

320

Inducing bistability with local electret technology in a microcantilever based non-linear vibration energy harvester  

NASA Astrophysics Data System (ADS)

A micro-electro-mechanical system based vibration energy harvester is studied exploring the benefits of bistable non linear dynamics in terms of energy conversion. An electrostatic based approach to achieve bistability, which consists in the repulsive interaction between two electrets locally charged in both tip free ends of an atomic force microscope cantilever and a counter electrode, is experimentally demonstrated. A simple model allows the prediction of the measured dynamics of the system, which shows an optimal distance between the cantilever and the counter electrode in terms of the root mean square vibration response to a colored Gaussian excitation noise.

López-Suárez, M.; Agustí, J.; Torres, F.; Rurali, R.; Abadal, G.

2013-04-01

321

Development of new vibration energy flow analysis software and its applications to vehicle systems  

NASA Astrophysics Data System (ADS)

The Energy flow analysis (EFA) offers very promising results in predicting the noise and vibration responses of system structures in medium-to-high frequency ranges. We have developed the Energy flow finite element method (EFFEM) based software, EFADSC++ R4, for the vibration analysis. The software can analyze the system structures composed of beam, plate, spring-damper, rigid body elements and many other components developed, and has many useful functions in analysis. For convenient use of the software, the main functions of the whole software are modularized into translator, model-converter, and solver. The translator module makes it possible to use finite element (FE) model for the vibration analysis. The model-converter module changes FE model into energy flow finite element (EFFE) model, and generates joint elements to cover the vibrational attenuation in the complex structures composed of various elements and can solve the joint element equations by using the wave tra! nsmission approach very quickly. The solver module supports the various direct and iterative solvers for multi-DOF structures. The predictions of vibration for real vehicles by using the developed software were performed successfully.

Kim, D.-J.; Hong, S.-Y.; Park, Y.-H.

2005-09-01

322

Modal Analysis and Study of the Vibration Characteristics of the Thermoelectric Modules of Vehicle Exhaust Power-Generation Systems  

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

323

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

PubMed

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

324

Origin of Low-Energy Quadrupole Collectivity in Vibrational Nuclei  

SciTech Connect

The coupling of the giant quadrupole resonance to valence-space configurations is shown to be the origin of the formation of low-lying quadrupole-collective structures in vibrational nuclei with symmetric and mixed-symmetric character with respect to the proton-neutron degree of freedom. For the first time experimental evidence for this picture is obtained from electron- and proton scattering experiments on the nucleus {sup 92}Zr that are sensitive to the relative phase of valence-space amplitudes by quantum interference.

Walz, C.; Krugmann, A.; Neumann-Cosel, P. von; Pietralla, N.; Ponomarev, V. Yu.; Scheikh-Obeid, A. [Institut fuer Kernphysik, Technische Universitaet Darmstadt, 64289 Darmstadt (Germany); Fujita, H. [Department of Physics, Osaka University, Toyonaka, Osaka 560-0043 (Japan); iThemba LABS, Post Office Box 722, Somerset West 7129 (South Africa); Wambach, J. [Institut fuer Kernphysik, Technische Universitaet Darmstadt, 64289 Darmstadt (Germany); GSI Helmholtzzentrum fuer Schwerionenforschung, D-64291 Darmstadt (Germany)

2011-02-11

325

The Physics Classroom: Work, Energy, and Power  

NSDL National Science Digital Library

This chapter of The Physics Classroom tutorial ties together the concepts of work, power, and the Law of Conservation of Energy. Six interactive tutorials explore kinetic and potential energy, power, mechanical energy, and the relationship between energy and forces. It also gives students practice in calculating work and using energy bar charts. f

Henderson, Tom

2005-03-16

326

An investigation into the simultaneous use of a resonator as an energy harvester and a vibration absorber  

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

327

Angularly resolved rotational energy transfer in highly vibrationally excited states: Na sub 2 ( v =31)--Ne  

SciTech Connect

The scattering of high vibrationally excited sodium molecules Na{sub 2}({ital v}=31) with Ne atoms at 180 meV collision energy is investigated in a crossed molecular beam arrangement using laser optical methods. Angularly resolved rotationally inelastic and vibrationally elastic cross sections {ital j}{sub {ital i}}{r arrow}{ital j}{sub {ital f}} are measured for {ital j}{sub {ital i}} =5, 7, and 9{le}{ital j}{sub {ital f}} {le}25. Pronounced rotational rainbow maxima are observed, the angular position of which indicates a significantly larger anisotropy of the interaction potential compared to that of Na{sub 2}({ital v}=0)--Ne. Except for the increase of the anisotropy the vibrational excitation has little effect on the dynamics of rotational energy transfer. Good agreement with a new semiempirical Na{sub 2}--Ne potential surface {ital V}({ital r},{ital R},{gamma}) is found.

Ziegler, G.; Kumar, S.V.K.; Rubahn, H.; Kuhn, A.; Sun, B.; Bergmann, K. (Fachbereich Physik, Universitaet Kaiserslautern, D-6750 Kaiserslautern, Germany (DE))

1991-03-15

328

Time scales and pathways of vibrational energy relaxation in liquid CHBr3 and CDBr3  

NASA Astrophysics Data System (ADS)

Molecular dynamics simulations are used in conjunction with Landau-Teller, fluctuating Landau-Teller, and time-dependent perturbation theories to investigate energy flow out of various vibrational states of liquid CHBr3 and CDBr3. The CH stretch overtone is found to relax with a time scale of about 1 ps compared to the 50 ps rate for the fundamental. The relaxation pathways and rates for the CD stretch decay in CDBr3 are computed in order to understand the changes arising from deuteration. While the computed relaxation rate agrees well with experiments, the pathway is found to be more complex than anticipated. In addition to the above channels for CH(D) stretch relaxation that involve only the hindered translations and rotations of the solvent, routes involving off-resonant and resonant excitations of solvent vibrational modes are also examined. Finally, the decay of energy from low frequency states to near-lying solute states and solvent vibrations are studied.

Ramesh, Sai G.; Sibert, Edwin L.

2006-12-01

329

Near-Resonant Vibration Implies Vibration Energy Transfer under Single-Collision Conditions.  

National Technical Information Service (NTIS)

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. (ERA citation 06:019033)

D. M. Breener

1981-01-01

330

Tidal energy in electric power systems  

Microsoft Academic Search

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

331

Platform architecture for solar, thermal and vibration energy combining with MPPT and single inductor  

Microsoft Academic Search

A 0.35?m CMOS energy processor with multiple inputs from solar, thermal and vibration energy sources is presented. Dual-path architecture for energy harvesting is proposed that has up to 13% higher conversion efficiency compared to the conventional two stage storage-regulation architecture. To minimize the cost and form factor, a single inductor has been time shared for all converters. A novel low

Saurav Bandyopadhyay; Anantha P. Chandrakasan

2011-01-01

332

Two self-powered energy harvesting interfaces based on the optimized synchronous electric charge extraction technique  

NASA Astrophysics Data System (ADS)

Optimized synchronous electric charge extraction (OSECE) interface is a load weakly-dependant circuit, which is a favorable characteristic for piezoelectric wideband vibration energy harvesting. However, it introduces synchronous switches that need to be self-powered in a stand-alone system. This paper presents the design and experimental testing of two self-powered approaches for the OSECE technique. One is made of electronic switches driven by analog peak detector circuits; the other uses mechanical switches directly controlled by the ambient vibrations. Finally, advantages and drawbacks of the two approaches will be compared and discussed.

Wu, Yipeng; Badel, Adrien; Formosa, Fabien; Liu, Weiqun; Agbossou, Amen

2013-12-01

333

Neutron number dependence of the energies of the ?-vibrational states in nuclei with Z˜100 and the manifestation of pseudospin symmetry  

NASA Astrophysics Data System (ADS)

Background: The symmetry-guided methods have shown their power over many years of nuclear physics research. It was found that the concept of the pseudospin symmetry is very helpful in providing a simple explanation of many features of heavy nuclei.Purpose: To show, based on the results of calculations of the energies of the ?-vibrational states in nuclei with Z˜100, that the experimental data on these energies will give us information indicating how well the pseudospin symmetry is realized in these exotic nuclei.Method: The quasiparticle-phonon model is used to calculate the energies of the ?-vibrational states.Results: It is shown that the energies of the ?-vibrational states in the Cm, Cf, Fm, No, and Rf isotopes considered as the functions of the number of neutrons N have a minimum at N=156 when the neutron Fermi level lies just between the following neutron single particle levels: 3/2[622] and 1/2[620] which belong to the pseudospin doublet. It is shown that the corresponding two-quasiparticle component gives the main contribution to the structure of the ? phonon.Conclusion: The experimental information on the energies of the ?-vibrational states in nuclei with Z˜100 can be used to determine a splitting of the [521]˜ pseudospin doublet.

Jolos, R. V.; Shirikova, N. Yi.; Sushkov, A. V.

2012-10-01

334

Low-energy vibrational dynamics of cesium borate glasses.  

PubMed

Low-temperature specific heat and inelastic light scattering experiments have been performed on a series of cesium borate glasses and on a cesium borate crystal. Raman measurements on the crystalline sample have revealed the existence of cesium rattling modes in the same frequency region where glasses exhibit the boson peak (BP). These localized modes are supposed to overlap with the BP in cesium borate glasses affecting its magnitude. Their influence on the low frequency vibrational dynamics in glassy samples has been considered, and their contribution to the specific heat has been estimated. Evidence for a relation between the changes of the BP induced by the increased amount of metallic oxide and the variations of the elastic medium has been provided. PMID:22546082

Crupi, C; D'Angelo, G; Vasi, C

2012-06-01

335

Optimized Structure and Vibrational Properties by Error Affected Potential Energy Surfaces  

PubMed Central

The precise theoretical determination of the geometrical parameters of molecules at the minima of their potential energy surface and of the corresponding vibrational properties are of fundamental importance for the interpretation of vibrational spectroscopy experiments. Quantum Monte Carlo techniques are correlated electronic structure methods promising for large molecules, which are intrinsically affected by stochastic errors on both energy and force calculations, making the mentioned calculations more challenging with respect to other more traditional quantum chemistry tools. To circumvent this drawback in the present work, we formulate the general problem of evaluating the molecular equilibrium structures, the harmonic frequencies, and the anharmonic coefficients of an error affected potential energy surface. The proposed approach, based on a multidimensional fitting procedure, is illustrated together with a critical evaluation of systematic and statistical errors. We observe that the use of forces instead of energies in the fitting procedure reduces the statistical uncertainty of the vibrational parameters by 1 order of magnitude. Preliminary results based on variational Monte Carlo calculations on the water molecule demonstrate the possibility to evaluate geometrical parameters and harmonic and anharmonic coefficients at this level of theory with an affordable computational cost and a small stochastic uncertainty (<0.07% for geometries and <0.7% for vibrational properties).

Zen, Andrea; Zhelyazov, Delyan; Guidoni, Leonardo

2013-01-01

336

Vibration energy harvesting based on integrated piezoelectric components operating in different modes  

Microsoft Academic Search

To increase the vibration energy-harvesting capability of the piezoelectric generator based on a cantilever beam, we have proposed a piezoelectric generator that not only uses the strain change of piezoelectric components bonded on a cantilever beam, but also employs the weights at the tip of the cantilever beam to hit piezoelectric components located on the 2 sides of weights. A

Junhui Hu; Januar Jong; Chunsheng Zhao

2010-01-01

337

MEMS Vibration Energy Harvesting Devices With Passive Resonance Frequency Adaptation Capability  

Microsoft Academic Search

Further advancement of ambient mechanical vibration energy harvesting depends on finding a simple yet efficient method of tuning the resonance frequency of the harvester to match the one dominant in the environment. We propose an innovative approach to achieve a completely passive, wideband adaptive system by employing mechanical nonlinear strain stiffening. We present analytical analysis of the underlying idea as

Marcin Marzencki; Maxime Defosseux; Skandar Basrour

2009-01-01

338

Potential energy function and vibrational states of HN3 and DN3  

Microsoft Academic Search

Eight different six-dimensional potential energy functions for the electronic ground state of the HN3 have been generated by the CCSD(T) method and various density functional approaches. The potentials in their analytic forms have been used in variational calculations of the vibrational states (J = 0). The calculated anharmonic wavenumbers for the fundamentals agree with the known experimental values to within

Matthias Rosenstock; Pave Rosmus; Oliver Treutler; Stuart Carter; Ernst-Albert Reinsch; Nicholas C. Handy

1998-01-01

339

Modeling vibrational dephasing and energy relaxation of intramolecular anharmonic modes for multidimensional infrared spectroscopies  

NASA Astrophysics Data System (ADS)

Starting from a system-bath Hamiltonian in a molecular coordinate representation, we examine an applicability of a stochastic multilevel model for vibrational dephasing and energy relaxation in multidimensional infrared spectroscopy. We consider an intramolecular anharmonic mode nonlinearly coupled to a colored noise bath at finite temperature. The system-bath interaction is assumed linear plus square in the system coordinate, but linear in the bath coordinates. The square-linear system-bath interaction leads to dephasing due to the frequency fluctuation of system vibration, while the linear-linear interaction contributes to energy relaxation and a part of dephasing arises from anharmonicity. To clarify the role and origin of vibrational dephasing and energy relaxation in the stochastic model, the system part is then transformed into an energy eigenstate representation without using the rotating wave approximation. Two-dimensional (2D) infrared spectra are then calculated by solving a low-temperature corrected quantum Fokker-Planck (LTC-QFP) equation for a colored noise bath and by the stochastic theory. In motional narrowing regime, the spectra from the stochastic model are quite different from those from the LTC-QFP. In spectral diffusion regime, however, the 2D line shapes from the stochastic model resemble those from the LTC-QFP besides the blueshifts caused by the dissipation from the colored noise bath. The preconditions for validity of the stochastic theory for molecular vibrational motion are also discussed.

Ishizaki, Akihito; Tanimura, Yoshitaka

2006-08-01

340

Design Synthesis of Electromagnetic Vibration-Driven Energy Generators Using a Variational Formulation  

Microsoft Academic Search

This paper reports upon the design of electromag- netic vibration-driven energy generators using a variational for- mulation to derive the equation of motion of such generators, thereby gaining insight into the device physics. Using this ap- proach, the characteristics of the generator are analytically stud- ied, a newly developed optimization theory of the generator is derived, and a guide for

Emmanuel Bouendeu; Andreas Greiner; Patrick J. Smith; Jan G. Korvink

2011-01-01

341

Compact and Low-Frequency Vibration Energy Scavenger using the longitudinal excitation of a piezoelectric bar  

NASA Astrophysics Data System (ADS)

This paper introduces an innovative architecture of a piezoelectric harvester, which enables harvesting vibration energy at low frequency using the {33}-transduction mode of a piezoelectric element. Unlike cantilevers integrating ferroelectric material combined with interdigitated electrodes, the concept that we propose is based on the elongation/compression excitation of a piezoelectric bar.

Colin, M.; Mortier, Q.; Basrour, S.; Bencheikh, N.

2013-12-01

342

Conductivity in semiconductors induced by vibrational-to-electronic energy transfer  

NASA Astrophysics Data System (ADS)

A theoretical approach is presented for vibrational-to-electronic energy transfer at a semiconductor surface due to an impinging polar molecule. Results for the HCl + InSb and HCl + PbSe systems under thermal conditions indicate transition probabilities in the range 0.1 to 10%, which can be readily observed by experimental measurements of the semiconductor electrical conductivity.

Last, I.; George, T. F.; Perry, D. S.

1984-03-01

343

A Scaling Law for Vibration Response of Laminated Doubly Curved Shallow Shells by Energy Approach  

Microsoft Academic Search

This research paper derives the scaling law for physical modeling of generally laminated doubly curved shallow shells for free vibration response by applying the similitude transformation to the governing total energy of the system. Validity of the scaling law is verified by numerical experiments on laminated doubly curved shallow shells. This is accomplished by calculating theoretically the natural frequencies for

Variddhi Ungbhakorn; Pairod Singhatanadgid

2009-01-01

344

Fundamental kinetics and innovative applications of nonequilibrium atomic vibration in thermal energy transport and conversion  

NASA Astrophysics Data System (ADS)

All energy conversion inefficiencies begin with emission of resonant atomic motions, e.g., vibrations, and are declared as waste heat once these motions thermalize to equilibrium. The nonequilibrium energy occupancy of the vibrational modes can be targeted as a harvestable, low entropy energy source for direct conversion to electric energy. Since the lifetime of these resonant vibrations is short, special nanostructures are required with the appropriate tuning of the kinetics. These in turn require multiscale, multiphysics treatments. Atomic vibration is described with quasiparticle phonon in solid, and the optical phonon emission is dominant relaxation channel in semiconductors. These optical modes become over-occupied when their emission rate becomes larger than their decay rate, thus hindering energy relaxation and transport in devices. Effective removal of these phonons by drifting electrons is investigated by manipulating the electron distribution to have higher population in the low-energy states, thus allowing favorable phonon absorption. This is done through introduction, design and analysis of a heterobarrier conducting current, where the band gap is controlled by alloying, thus creating a spatial variation which is abrupt followed by a linear gradient (to ensure directed current). Self-consistent ensemble Monte Carlo simulations based on interaction kinetics between electron and phonon show that up to 19% of the phonon energy is converted to electric potential with an optimized GaAs/AlxGa1-xAs barrier structure over a range of current and electron densities, and this system is also verified through statistical entropy analysis. This direct energy conversion improves the device performance with lower operation temperature and enhances overall energy conversion efficiency. Through this study, the paradigm for harvesting the resonant atomic vibration is proposed, reversing the general role of phonon as only causing electric potential drop. Fundamentals pertaining to thermal energy transport and conversion are further explored by directly addressing the nonequilibria in phonon and molecular vibration. Enhancement of the laser cooling performance in molecular gas is examined by nonequilibrium interaction kinetics between molecules and photons. Thermal energy transport across interfaces and junctions is also studied, and decomposition of thermal interfacial resistance, atomic restructuring, and phonon wave features are addressed.

Shin, Seungha

345

Effects of vibration and shock on the performance of gas-bearing space-power Brayton cycle turbomachinery. Part 4: Suppression of rotor-bearing system vibrations through flexible bearing support damping  

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

346

A flex-compressive-mode piezoelectric transducer for mechanical vibration/strain energy harvesting.  

PubMed

A piezoelectric transducer for harvesting energy from ambient mechanical vibrations/strains under pressure condition was developed. The proposed transducer was made of two ring-type piezoelectric stacks, one pair of bow-shaped elastic plates, and one shaft that pre-compresses them. This transducer works in flex-compressive (F-C) mode, which is different from a conventional flex-tensional (F-T) one, to transfer a transversely applied force F into an amplified longitudinal force N pressing against the two piezo-stacks via the two bowshaped elastic plates, generating a large electric voltage output via piezoelectric effect. Our experimental results show that without an electric load, an F-C mode piezo-transducer could generate a maximum electric voltage output of up to 110 Vpp, and with an electric load of 40 ??, it a maximum power output of 14.6 mW under an acceleration excitation of 1 g peak-peak at the resonance frequency of 87 Hz. PMID:21507747

Li, Xiaotian; Guo, Mingsen; Dong, Shuxiang

2011-04-01

347

Transformation of potential energy surfaces for estimating isotopic shifts in anharmonic vibrational frequency calculations.  

PubMed

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

348

Transformation of potential energy surfaces for estimating isotopic shifts in anharmonic vibrational frequency calculations  

NASA Astrophysics Data System (ADS)

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; Berger, Robert; Rauhut, Guntram

2014-05-01

349

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

350

Power Technologies Energy Data Book. Third Edition.  

National Technical Information Service (NTIS)

In 2002, the Energy Analysis Office of the National Renewable Energy Laboratory (NREL) developed the first version of the Power Technologies Energy Data Book for the Office of Power Technologies of the U.S. Department of Energy (DOE). The main purpose of ...

2005-01-01

351

COMPARISON OF SUBJECTIVE RESPONSES TO VIBRATION AND SHOCK WITH STANDARD ANALYSIS METHODS AND ABSORBED POWER  

Microsoft Academic Search

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

N. J. MANSFIELD; P. Holmlund; R. Lundström

2000-01-01

352

Apparatus for generating seismic vibration energy in a borehole  

SciTech Connect

A signal generating apparatus is described for use in fluid-filled boreholes, comprising: a frame for suspension in the borehole; a tube having first and second ends and disposed in the frame a first acoustic energy source mounted in the first end to direct energy to a central point; a second acoustic energy source mounted in the second end to direct energy to the central point; an energy deflector plate disposed at 45 degrees to and along the axis of the tube central point at an equal angle to each means for energizing the first and second acoustic energy sources.

Benzing, W.M.

1986-12-30

353

Diamagnetic levitation for nonlinear vibration energy harvesting: Theoretical modeling and analysis  

NASA Astrophysics Data System (ADS)

This paper provides theoretical modeling and analysis of applying diamagnetic levitation for nonlinear vibration energy harvesting in detail by first identifying potential merits as well as limitations. Based on a magnetic dipole model, analytical analysis is conducted by providing simplified analytical expressions of restoring forces and electromagnetic damping which are then transformed into a hardening spring model and results in a Duffing equation with strong nonlinearity. In addition, constraints on physical geometry are discussed and derived in the view of practical energy harvester design. More importantly, the derivation and discussion extended to multi-well potential suggest that diamagnetic levitation may enable designing an energy harvester that subject to cross-well chaos with a compact volume and wideband responses. Without mechanical damping in any form, diamagnetic levitation may be considered as a promising mechanism for developing vibration energy harvesters with great performance, and the paper provides a technology push on the possibility.

Liu, Lei; Yuan, F. G.

2013-01-01

354

Energy trapping of thickness-shear vibration modes of elastic plates with functionally graded materials.  

PubMed

Energy trapping has important applications in the design of thickness-shear resonators. Considerable efforts have been made for the effective utilization and improvement of energy trapping with variations of plate configurations, such as adding electrodes and contouring. As a new approach in seeking improved energy trapping feature, we analyze thickness-shear vibrations in an elastic plate with functionally graded material (FGM) of in-plane variation of mechanical properties, such as elastic constants and density. A simple and general equation governing the thickness-shear modes is derived from a variational analysis. A plate with piecewise constant material properties is analyzed as an example. It is shown that such a plate can support thickness-shear vibration modes with obvious energy trapping. Bechmann's number for the existence of only one trapped mode also can be determined accordingly. PMID:17375839

Wang, Ji; Yang, Jiashi; Li, Jiangyu

2007-03-01

355

Shock-induced melting of (100)-oriented nitromethane: Energy partitioning and vibrational mode heating  

NASA Astrophysics Data System (ADS)

A study of the structural relaxation of nitromethane subsequent to shock loading normal to the (100) crystal plane performed using molecular dynamics and a nonreactive potential was reported recently [J. Chem. Phys. 131, 064503 (2009)]. Starting from initial temperatures of T0=50 and 200 K, shocks were simulated using impact velocities Up ranging from 0.5 to 3.0 km s-1 clear evidence of melting was obtained for shocks initiated with impacts of 2.0 km s-1 and higher. Here, we report the results of analyses of those simulation data using a method based on the Eckart frame normal-mode analysis that allows partitioning of the kinetic energy among the molecular degrees of freedom. A description of the energy transfer is obtained in terms of average translational and rotational kinetic energies in addition to the rates of individual vibrational mode heating. Generally, at early times postshock a large superheating of the translational and rotational degrees of freedom (corresponding to phonon modes of the crystal) is observed. The lowest frequency vibrations (gateway modes) are rapidly excited and also exhibit superheating. Excitation of the remaining vibrational modes occurs more slowly. A rapid, early excitation of the symmetric C-H stretch mode was observed for the shock conditions T0=50 K and Up=2.0 km s-1 due to a combination of favorable alignment of molecular orientation with the shock direction and frequency matching between the vibration and shock velocity.

Dawes, Richard; Siavosh-Haghighi, Ali; Sewell, Thomas D.; Thompson, Donald L.

2009-12-01

356

The power output and efficiency of a negative capacitance shunt for vibration control of a flexural system  

NASA Astrophysics Data System (ADS)

A negative capacitance shunt is a basic, analog, active circuit electrically connected to a piezoelectric transducer to control the vibrations of flexural bodies. The shunt circuit consists of a resistor and a synthetic negative capacitor to introduce a real and imaginary impedance on a vibrating mechanical system. The electrical impedance of the negative capacitance shunt modifies the effective modulus of the piezoelectric transducer to reduce the stiffness and increase the damping, which causes a decrease in amplitude of the vibrating structure to which the elements are bonded. To gain an insight into the electromechanical coupling and power output, the shunt and the electrical properties of the piezoelectric transducer are modeled using circuit modeling software. The power output of the model is validated with experimental measurements of a shunt connected to a piezoelectric transducer pair bonded to a vibrating aluminum cantilever beam. The model is used to select the passive components of the negative capacitance shunt to increase the efficiency and quantify the voltage output limit of the op-amp.

Beck, Benjamin S.; Cunefare, Kenneth A.; Collet, Manuel

2013-06-01

357

Evaluation of energy dissipation mechanisms in vibrational microactuators  

Microsoft Academic Search

The energy dissipation characteristics of beam-shaped microactuators are analytically evaluated here as a first step in establishing a design method that minimizes their energy consumption. The energy dissipation by airflow force is calculated by using the Navier-Stokes equation and its accuracy is verified by comparing it with experimental results. Additionally, the dissipations due to squeeze force, internal friction, and support

Hiroshi HOSAKA; Kiyoshi ITAO; Susumu KURODA

1994-01-01

358

Mode-specific intermolecular vibrational energy transfer. II. Deuterated water and potassium selenocyanate mixture  

Microsoft Academic Search

Vibrational energy transfer from the first excited state (2635 cm-1) of the O-D stretch of deuterated water (D2O) to the 0-1 transition (2075 cm-1) of the CN stretch of potassium selenocyanate (KSeCN) in their 2.5:1 liquid mixture was observed with a multiple-mode two dimensional infrared spectroscopic technique. Despite the big energy mismatch (560 cm-1) between the two modes, the transfer

Hongtao Bian; Xiewen Wen; Jiebo Li; Junrong Zheng

2010-01-01

359

Non-resonant electromagnetic wideband energy harvesting mechanism for low frequency vibrations  

Microsoft Academic Search

A novel non-resonant energy harvesting mechanism with wide operation frequency band is investigated for collecting energy\\u000a from low frequency ambient vibration. A free-standing magnet is packaged inside a sealed hole which is created by stacking\\u000a five pieces of printed circuit board substrates embedded with multi-layer copper coils. This device was tested under various\\u000a acceleration conditions. Considering the air damping effect,

Bin Yang; Chengkuo Lee

2010-01-01

360

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

361

Anisotropy of surface vibration measured by temperature dependence of the spot intensity in reflection high-energy electron diffraction  

NASA Astrophysics Data System (ADS)

A handy method has recently been developed to investigate atomic vibration on a surface using reflection high-energy electron diffraction. We measured the temperature dependence of many spot intensities to obtain the angular dependence of Debye-Waller factors, from which the angular-dependence amplitudes of atomic vibration on surface can be deduced. We applied this method on a Si(111)3×3-Ga surface. The obtained perpendicular vibrational amplitude of Ga was 0.11Å , which is in good agreement with those obtained by other works. The lateral vibrational amplitude is 0.07Å , which was observed directly for the first time.

Hashimoto, Mie; Takeda, Sakura Nishino; Daimon, Hiroshi

2005-03-01

362

Piezoelectrochemical effect: Mechanical energy induced redox reaction in aqueous solutions through vibrating piezoelectric materials  

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

363

Parametric Energy Coupled Uninterruptible Power Supply.  

National Technical Information Service (NTIS)

A parametric energy coupling system is described for providing uninterruptible a-c power to electrical loads. In a normal mode, a parametric transformer couples a-c line power directly from an a-c power source to a load. Upon a power outage occurrence, an...

D. M. Hannemann D. M. Shiroma K. T. Huang

1977-01-01

364

Active Power and Nonactive Power Control of Distributed Energy Resources  

SciTech Connect

Distributed energy resources (DE) have been widely used in the power systems to supply active power, and most of the present DE resources are operated with limited or without nonactive power capability. This paper shows that with a slight modification in hardware configuration and a small boost in the power ratings, as well as proper implementation of control strategies, a DE system with a power electronics converter interface can provide active power and nonactive power simultaneously and independently. A DE can provide dynamic voltage regulation to the local bus because of its nonactive power capability. Furthermore, the proposed DE control method in this paper can effectively compensate the unbalance in the local voltage. The system requirements such as the inverter current rating and the dc voltage rating are discussed. The analysis of the system requirements to provide nonactive power shows that it is cost-effective to have DE provide voltage regulation.

Xu, Yan [ORNL; Li, Fangxing [ORNL; Rizy, D Tom [ORNL; Kueck, John D [ORNL

2008-01-01

365

Potential energy surface and vibrational band origins of the triatomic lithium cation  

NASA Astrophysics Data System (ADS)

The 104 point CISD Li +3 potential energy surface and its analytical representation is reported. The calculations predict the minimum energy geometry to be an equilateral triangle of side RLi?Li = 3.0 Å and of energy - 22.20506 E h. A fifth-order Morse—Dunham type analytical force field is used in the Carney—Porter normal co-ordinate vibrational Hamiltonian, the corresponding eigenvalue problem being solved variationally using a 560 configurational finite-element basis set. The predicted assignment of the vibrational band origins is in accord with that reported for H +3. Moreover, for 6Li +3 and 7Li +3 the lowest i.r. accessible band origin is the overline?0,1,±1 predicted to be at 243.6 and 226.0 cm -1 respectively.

Searles, Debra J.; Dunne, Simon J.; von Nagy-Felsobuki, Ellak I.

366

New Method for Measuring Mechanical Vibration Loss and Dielectric Loss of Piezoelectric Transducer under High-Power Excitation  

Microsoft Academic Search

In the Pb(Zr, Ti)O3 group ceramics, the dielectric loss becomes larger than the mechanical vibration loss under high-power excitation. In this paper, a new advanced method for measuring these losses separately and simultaneously is described. The two-step differential circuit is utilized. By adjusting the differential circuits, the dielectric loss and the damped capacitance are obtained. The resonance circuit constants under

Seiji Hirose

1994-01-01

367

Flow-induced vibration  

SciTech Connect

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

368

Power management in energy harvesting sensor networks  

Microsoft Academic Search

Power management is an important concern in sensor networks, because a tethered energy infrastructure is usually not available and an obvious concern is to use the available battery energy efficiently. However, in some of the sensor networking applications, an additional facility is available to ameliorate the energy problem: harvesting energy from the environment. Certain considerations in using an energy harvesting

Aman Kansal; Jason Hsu; Sadaf Zahedi; Mani B. Srivastava

2007-01-01

369

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

370

Power marketing and renewable energy  

SciTech Connect

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

371

Power Composites: Structural Materials that Generate and Store Electrical Energy.  

National Technical Information Service (NTIS)

We describe progress in the development of a synthetic multifunctional material: namely a fiber composite with both power and structural function. The structural composite contains batteries encased in piezoelectric tubes. When the structure vibrates the ...

D. A. Shockey S. C. Ventura S. C. Narang J. W. Simons B. C. Bourne

2005-01-01

372

Electromagnetic energy harvesting from vibrations of multiple frequencies  

Microsoft Academic Search

A novel multi-frequency energy harvester has been designed and fabricated, which consists of three permanent magnets, three sets of two-layer copper coils and a supported beam of acrylic, while these coils are made of thin fire resistant 4 (FR4) substrates using a standard printed circuit board. The energy under the first, second and third resonant modes can be harvested, corresponding

Bin Yang; Chengkuo Lee; Wenfeng Xiang; Jin Xie; Johnny Han He; Rama Krishna Kotlanka; Siew Ping Low; Hanhua Feng

2009-01-01

373

Power quality improvement and uninterruptible power supply using a power conditioning system with energy storage capability  

Microsoft Academic Search

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

374

Energy analysis of wave and tidal power  

NASA Astrophysics Data System (ADS)

Energy requirements for building wave- and tidal-power systems are estimated and the relationship between energy requirements and extraction efficiency is examined for wavepower systems. It is found that a point of maximum net output is reached, beyond which further increases in extraction efficiency result in decreased net energy. In this manner, the energy analysis identifies a limit on the energy which could, in principle, be extracted by a wave-energy system. Finally, it is noted that although similar limits could be identified for other types of energy sources, the tidal power analysis is confined to a brief comparison of energy inputs and outputs.

Harrison, R.; Smith, K. G.; Varley, J. S.

1980-06-01

375

Power Measurement Methods for Energy Efficient Applications  

PubMed Central

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.

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

2013-01-01

376

Near-resonant energy transfer from highly vibrationally excited OH to N2.  

PubMed

The probability per collision P(T) of near-resonant vibration-to-vibration energy transfer (ET) of one quantum of vibrational energy from vibrational levels nu=8 and nu=9 of OH to N(2)(nu=0), OH(nu)+N(2)(0)-->OH(nu-1)+N(2)(1), is calculated in the 100-350 K temperature range. These processes represent important steps in a model that explains the enhanced 4.3 microm emission from CO(2) in the nocturnal mesosphere. The calculated energy transfer is mediated by weak long-range dipole-quadrupole interaction. The results of this calculation are very sensitive to the strength of the two transition moments. Because of the long range of the intermolecular potential, the resonance function, a measure of energy that can be efficiently exchanged between translation and vibration-rotation degrees of freedom, is rather narrow. A narrow resonance function coupled with the large rotational constant of OH is shown to render the results of the calculation very sensitive to the rotational distribution, or the rotational temperature if one exists, of this molecule. The calculations are carried out in the first and second orders of perturbation theory with the latter shown to give ET probabilities that are an order of magnitude larger than the former. The reasons for the difference in magnitude and temperature dependence of the first- and second-order calculations are discussed. The results of the calculations are compared with room temperature measurements as well as with an earlier calculation. Our calculated results are in good agreement with the room temperature measurements for the transfer of vibrational energy for the exothermic OH(nu=9) ET process but are about an order lower than the room temperature measurements for the exothermic OH(nu=8) ET process. The cause of this discrepancy is explored. This calculation does not give the large values of the rate coefficients needed by the model that explains the enhanced 4.3 microm emission from CO(2) in the nocturnal mesosphere. PMID:18376923

Burtt, Kelly D; Sharma, Ramesh D

2008-03-28

377

Kinetic model for the vibrational energy exchange in flowing molecular gas mixtures. Ph.D. Thesis  

NASA Technical Reports Server (NTRS)

The present study is concerned with the development of a computational model for the description of the vibrational energy exchange in flowing gas mixtures, taking into account a given number of energy levels for each vibrational degree of freedom. It is possible to select an arbitrary number of energy levels. The presented model uses values in the range from 10 to approximately 40. The distribution of energy with respect to these levels can differ from the equilibrium distribution. The kinetic model developed can be employed for arbitrary gaseous mixtures with an arbitrary number of vibrational degrees of freedom for each type of gas. The application of the model to CO2-H2ON2-O2-He mixtures is discussed. The obtained relations can be utilized in a study of the suitability of radiation-related transitional processes, involving the CO2 molecule, for laser applications. It is found that the computational results provided by the model agree very well with experimental data obtained for a CO2 laser. Possibilities for the activation of a 16-micron and 14-micron laser are considered.

Offenhaeuser, F.

1987-01-01

378

Vibrational structure of vinyl chloride cation studied by using one-photon zero-kinetic energy photoelectron spectroscopy.  

PubMed

The vibrational structure of vinyl chloride cation, CH(2)CHCl+ (X(2)A' '), has been studied by vacuum ultraviolet (VUV) zero-kinetic energy (ZEKE) photoelectron spectroscopy. Among nine symmetric vibrational modes, the fundamental frequencies of six modes have been determined. The first overtone of the out-of-plane CH(2) twist vibrational mode has been also measured. In addition to these, the combination and overtone bands of the above vibrational modes about 4500 cm(-1) above the ground state have been observed in the ZEKE spectrum. The vibrational band intensities of the ZEKE spectrum can be described approximately by the Franck-Condon factors with harmonic approximation. The ZEKE spectrum has been assigned based on the harmonic frequencies and Franck-Condon factors from theoretical calculations. The ionization energy (IE) of CH(2)CHCl is determined as 80705.5 +/- 2.5 (cm(-1)) or 10.0062 +/- 0.0003 (eV). PMID:17696413

Zhang, Ping; Li, Juan; Mo, Yuxiang

2007-09-01

379

Performance enhancement of a rotational energy harvester utilizing wind-induced vibration of an inclined stay cable  

NASA Astrophysics Data System (ADS)

In this paper, an innovative strategy for improving the performance of a recently developed rotational energy harvester is proposed. Its performance can be considerably enhanced by replacing the electromagnetic induction part, consisting of moving permanent magnets and a fixed solenoid coil, with a moving mass and a rotational generator (i.e., an electric motor). The proposed system is easily tuned to the natural frequency of a target structure using the position change of a proof mass. Owing to the high efficiency of the rotational generator, the device can more effectively harness electrical energy from the wind-induced vibration of a stay cable. Also, this new configuration makes the device more compact and geometrically tunable. In order to validate the effectiveness of the new configuration, a series of laboratory and field tests are carried out with the prototype of the proposed device, which is designed and fabricated based on the dynamic characteristics of the vibration of a stay cable installed in an in-service cable-stayed bridge. From the field test, it is observed that the normalized output power of the proposed system is 35.67 mW (m s-2)-2, while that of the original device is just 5.47 mW (m s-2)-2. These results show that the proposed device generates much more electrical energy than the original device. Moreover, it is verified that the proposed device can generate sufficient electricity to power a wireless sensor node placed on a cable under gentle-moderate wind conditions.

Kim, In-Ho; Jang, Seon-Jun; Jung, Hyung-Jo

2013-07-01

380

Solar-pumped electronic-to-vibrational energy transfer lasers  

NASA Technical Reports Server (NTRS)

The possibility of using solar-pumped lasers as solar energy converters is examined. The absorbing media considered are halogens or halogen compounds, which are dissociated to yield excited atoms, which then hand over energy to a molecular lasing medium. Estimates of the temperature effects for a Br2-CO2-He system with He as the cooling gas are given. High temperatures can cause the lower energy levels of the CO2 laser transition to be filled. The inverted populations are calculated and lasing should be possible. However, the efficiency is less than 0.001. Examination of other halogen-molecular lasant combinations (where the rate coefficients are known) indicate efficiencies in all cases of less than 0.005.

Harries, W. L.; Wilson, J. W.

1981-01-01

381

Free vibrations of an uncertain energy pumping system  

NASA Astrophysics Data System (ADS)

The aim of this paper is to study the energy pumping (the irreversible energy transfer from one structure, linear, to another structure, nonlinear) robustness considering the uncertainties of the parameters of a two DOF mass-spring-damper, composed of two subsystems, coupled by a linear spring: one linear subsystem, the primary structure, and one nonlinear subsystem, the so-called NES (nonlinear energy sink). Three parameters of the system will be considered as uncertain: the nonlinear stiffness and the two dampers. Random variables are associated to the uncertain parameters and probability density functions are constructed for the random variables applying the Maximum Entropy Principle. A sensitivity analysis is then performed, considering different levels of dispersion, and conclusions are obtained about the influence of the uncertain parameters in the robustness of the system.

Cataldo, Edson; Bellizzi, Sergio; Sampaio, Rubens

2013-12-01

382

A fuzzy-logic based dual-purpose adaptive circuit for vibration control and energy harvesting using piezoelectric transducer  

NASA Astrophysics Data System (ADS)

Due to their two-way electromechanical coupling effect, piezoelectric transducers can be used to synthesize passive vibration control schemes, e.g., RLC circuit with the integration of inductance and resistance elements that is conceptually similar to damped vibration absorber. Meanwhile, the wide usage of wireless sensors has led to the recent enthusiasm of developing piezoelectric-based energy harvesting devices that can convert ambient vibratory energy into useful electrical energy. It can be shown that the integration of circuitry elements such as resistance and inductance can benefit the energy harvesting capability. Here we explore a dual-purpose circuit that can facilitate simultaneous vibration suppression and energy harvesting. It is worth noting that the goal of vibration suppression and the goal of energy harvesting may not always complement each other. That is, the maximization of vibration suppression doesn't necessarily lead to the maximization of energy harvesting, and vice versa. In this research, we develop a fuzzy-logic based algorithm to decide the proper selection of circuitry elements to balance between the two goals. As the circuitry elements can be online tuned, this research yields an adaptive circuitry concept for the effective manipulation of system energy and vibration suppression. Comprehensive analyses are carried out to demonstrate the concept and operation.

Liu, Zhe Peng; Li, Qing

2013-04-01

383

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

384

Imaging bond breaking and vibrational energy transfer in small water containing clusters  

NASA Astrophysics Data System (ADS)

This letter presents a brief overview of our recent experimental studies of state-to-state vibrational predissociation (VP) dynamics of small hydrogen bonded (H-bonded) clusters following vibrational excitation. Velocity map imaging (VMI) and resonance-enhanced multiphoton ionization (REMPI) are used to determine accurate bond dissociation energies (D0) of (H2O)2, (H2O)3, HCl-H2O and NH3-H2O. Pair-correlated product energy distributions from the VP of these complexes are also presented and compared to theoretical models. Further insights into mechanisms are obtained from the recent quasi-classical trajectory (QCT) calculations of Bowman and coworkers. The D0 values for (H2O)2 and (H2O)3 are in very good agreement with recent calculated values, and the results are used to estimate the contributions of cooperative interactions to the H-bonding network.

Samanta, Amit K.; Ch'ng, Lee C.; Reisler, Hanna

2013-06-01

385

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

PubMed

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

386

Layout optimization methodology of piezoelectric transducers in energy-recycling semi-active vibration control systems  

NASA Astrophysics Data System (ADS)

An optimization methodology is proposed for the piezoelectric transducer (PZT) layout of an energy-recycling semi-active vibration control (ERSAVC) system for a space structure composed of trusses. Based on numerical optimization techniques, we intend to generate optimal location of PZTs under the constraint for the total length of PZTs. The design variables are set as the length of the PZT on each truss based on the concept of the ground structure approach. The transient problems of the mechanical and electrical vibrations based on the ERSAVC theory are considered as the equations of state. The objective is to minimize the integration of the square of all displacement over the whole analysis time domain. The sensitivity of the objective function is derived based on the adjoint variable method. Based on these formulations, an optimization algorithm is constructed using the fourth-order Runge-Kutta method and the method of moving asymptotes. Numerical examples are provided to illustrate the validity and utility of the proposed methodology. Using the proposed methodology, the optimal location of PZTs for the vibration suppression for multi-modal vibration is studied, which can be benchmark results of further study in the context of ERSAVC systems.

Takezawa, Akihiro; Makihara, Kanjuro; Kogiso, Nozomu; Kitamura, Mitsuru

2014-01-01

387

Quantum calculations of vibrational energies of H3O2- on an ab initio potential.  

PubMed

We report a full-dimensional potential energy surface for H3O2-, based on fitting 66,965 ab initio electronic energies. A major feature of this potential is a barrier of roughly 200 cm-1 to internal rotation of the two hydroxyl groups about a line connecting the two oxygen atoms and the bridging hydrogen atom. The potential is used in calculations of vibrational energies, performed with the "Reaction Path" version of the code "MULTIMODE". The results are compared to recent infrared messenger experiments and are used to propose interpretations of the experimental results. PMID:15099067

Huang, Xinchuan; Braams, Bastiaan J; Carter, Stuart; Bowman, Joel M

2004-04-28

388

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

PubMed

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

389

Vibrationally resolved translational energy release spectra from the ultraviolet photodissociation of methyl mercaptan  

Microsoft Academic Search

Product translational energy release spectra resulting from 248 and 193 nm photodissociation of methyl mercaptan are obtained for the hydrogen atom channels (CH3SH+h??CH3S+H) by using the high-n Rydberg time-of-flight technique. The spectra exhibit vibrational structure that is assigned to a CH3–S stretch progression. At 248 nm, the progression extends only to v=2, while at 193 nm levels up to approximately

J. Segall; Y. Wen; R. Singer; M. Dulligan; C. Wittig

1993-01-01

390

Energy function analysis for power system stability  

Microsoft Academic Search

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

391

High resolution electron energy loss studies of surface vibrations. Progress report, November 1, 1990--May 1, 1993.  

National Technical Information Service (NTIS)

New experimental investigations of surface vibrational properties of materials with high-resolution electron energy loss spectroscopy (EELS) are reported. This document summarizes progress over the last three year project period on surface phonon measurem...

L. L. Kesmodel

1993-01-01

392

Influence of Bipolar Pulse Poling Technique for Piezoelectric Vibration Energy Harvesters using Pb(Zr,Ti)O3 Films on 200 mm SOI Wafers  

NASA Astrophysics Data System (ADS)

Piezoelectric vibration energy harvester arrays using Pb(Zr,Ti)O3 thin films on 200 mm SOI wafers were fabricated. In-plane distribution of influence of bipolar pulse poling technique on direct current (DC) power output from the harvesters was investigated. The results indicate that combination poling treatment of DC and bipolar pulse poling increases a piezoelectric property and reduces a dielectric constant. It means that this poling technique improves the figure of merit of sensors and harvesters. Maximum DC power from a harvester treated by DC poling after bipolar pulse poling is about five times larger than a one treated by DC poling only.

Moriwaki, N.; Kobayashi, T.; Suzuki, Y.; Makimoto, N.; Fujimoto, K.; Suzuki, K.; Itoh, T.; Maeda, R.

2013-12-01

393

Real-time condition monitoring of thermal power plants feed-pumps by rolling bearings supports vibration  

NASA Astrophysics Data System (ADS)

The report addresses the real-time condition monitoring of technical state and automatic diagnosis of auxiliary equipment for bearings supports vibration, for example, control of the feed-pump operating modes of thermal power stations. The causes that lead to premature birth and development of defects in rolling bearings are identified and the development of activities ensuring safe and continuous operation of the auxiliary equipment of thermal power stations is carried out. Collection and analysis of vibration parameters of pumping units during their operation at the operating modes of the technological process are realized by means of real-time technical condition monitoring. Spectral analysis of vibration parameters of one of the pumps showed the presence of frequency components, which mark violations in the operating practices of the pump, the imbalance development and, as a consequence, the development of defects in the bearings by long-term operation of the unit. Timely warning of the personnel on the operation of the unit with the "INTOLERABLE" technical state and automatic warning issuance of the need to change the technological process allowed to recover the estimated pump operation mode in due time and prevent further development of defects in equipment.

Kostyukov, V. N.; Tarasov, E. V.

2012-05-01

394

Calculation of vibrational energy levels of triatomic molecules with the C 2v and C s symmetries by summing divergent series of the Rayleigh-Schrödinger perturbation theory  

NASA Astrophysics Data System (ADS)

The Rayleigh-Schrödinger perturbation theory is applied to calculation of vibrational energy levels of triatomic molecules with the C 2v and C s symmetries: SO2, H2S, F2O, HOF, HOCl, and DOCl. Particular attention is given to the states coupled by anharmonic resonances; for such states, the perturbation theory series diverge. To sum these series, the known methods of Padé, Padé-Borel, and Padé-Hermite and the method of power moments are used. For low-lying levels, all the summation methods give satisfactory results, while the method of quadratic Padé-Hermite approximants appears to be more efficient for high-excited states. Using these approximants, the structure of singularities of the vibrational energy, as a function in the complex plane, is studied.

Bykov, A. D.; Kalinin, K. V.

2012-03-01

395

Intramolecular Vibrational Energy Redistribution in the Reaction H_{3}^{+} + CO ? H_2 + HCO^+/HOC^+  

NASA Astrophysics Data System (ADS)

Observations of the rotational lines of HCO^+ produced in an extended negative glow discharge revealed high vibrational temperatures for the stretching vibrational modes, and non-thermal population distributions among the different ? levels of excited bending vibrational states. These results provide critical tests of our understanding of the dynamics and intramolecular vibrational energy redistribution (IVR) in this reaction process. The IVR in the HNC leftrightarrow HCN isomerization reaction has been studied previously by ab initio direct dynamics and vibration-mapping methods. An extension of the method used for the HNC/HCN isomerization reaction yields a new procedure for studying ``IVR in reactions'' which is applied to HCO^{+}/HOC^{+} production in the H_{3}^{+} + CO reaction, as described by the five-dimensional potential energy surface and pathways for this reaction reported recently by Li et al. Dynamics calculations have been performed for "co-linear configuration" reactions in which H_3^+ approaches the C end of CO with a translational temperature of 20 K (a typical kinetic temperature of dark clouds) or 330 K (a typical translational temperature for ions in a glow discharge). As H_3^+ approaches CO with the lower-temperature translational energy, the hopping of H^{+} to the CO moiety to form HCO^{+} occurs over a period of about 100 fs, and the H-C stretching mode of the product HCO^+ is highly excited. This excitation can relax within the same vibrational ladder and/or be transferred to the bending mode through anharmonic coupling. Details of direct dynamics calculations for this process will be reported. T. Hirao, S. Yu, and T. Amano,J. Chem. Phys., 127,074301 (2007). T. Hirao, S. Yu, and T. Amano, J. Mol. Spectrosc., 248, 26 (2008). Y. Kumeda, Y. Minami, K. Takano, T. Taketsugu, and T. Hirano, J. Mol. Struct. (THEOCHEM), 458, 285 (1999) T. Hirano, T. Taketsugu, and Y. Kurita, J. Phys. Chem., 98, 6936 (1994). H. Li, T. Hirano, T. Amano, and R.J. Le Roy, J. Chem. Phys., 129, 244306 (2008).

Hirano, Tsuneo; Li, Hui; Le Roy, Robert J.; Amano, Takayoshi

2009-06-01

396

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

397

Energy analysis of wave and tidal power  

Microsoft Academic Search

A methodology is developed for energy analysis of wave and tidal power based on the concepts of energy ratio defined as total output over lifetime of device divided by energy required to build the device or the output of the device over one year divided by energy requirements for one year's operation, and extraction efficiency, defined as total output of

R. Harrison; K. G. Smith; J. S. Varley

1979-01-01

398

Unified power engineering laboratory for electromechanical energy  

Microsoft Academic Search

Summary form only given. This paper introduces a unified power engineering laboratory capable of various experiments for power systems, power electronics and electromechanical energy conversion. It presents a flexible hardware setup, data acquisition (DAQ), and virtual instrumentation (VI), the base of our unified lab. Some features of virtual instrumentation are shown with real-time phasor diagrams, sequence component analysis, and spectral

T. Gedra; Seungwon An

2004-01-01

399

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

400

Measurement of laser energy and power  

Microsoft Academic Search

Measurements of laser energy and power are discussed with emphasis on those methods which attempt to establish the accuracy or standards for such measurements. Devices to attenuate laser radiation are summarized. The principles and limitations of the methods are stressed rather than design details of the apparatus. It is found that standards for the measurement of laser power and energy

GEORGE BIRNBAUM; MILTON BIRNBAUM

1967-01-01

401

Power electronics and alternative energy generation  

Microsoft Academic Search

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

402

Study on optical attenuation performance of special stock power optical cable based on a wind induced vibration environment in laboratory  

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

403

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

404

Energy regeneration from vibrationally excited methane in catalyst enhanced barrier discharges.  

NASA Astrophysics Data System (ADS)

Vibrationally excited species are the most abundant in methane-fed barrier discharges due to relatively low electron temperatures ( 5 eV). In the most cases, those exited energy is wasted as heat due to low reactivity. On the other hand, vibrationally excited methane show high-reactivity on a specific transition metal catalyst to dissociation. And we investigated energy regeneration from vibrationally excited methane in catalyst enhanced barrier discharges. The coaxial barrier discharge reactor packed with pellets of either SiO2 or 3wt%Ni/SiO2 was used for this purpose. Methane and water-vapor mixture was fed into the reactor at 200, 400, 600 degC. Catalyst could not activated at 200 degC, so plasma reaction (main products: C2H6, C3H8) become dominant. At 600 degC catalyst reaction was dominant, so main products were CO2 and H2. Most significant plasma and catalyst interaction was observed at 400 degC. Under this condition, methane dissociation by plasma and catalyst was expected.

Nozaki, Tomohiro; Muto, Nahoko; Kado, Shigeru; Okazaki, Ken

2002-10-01

405

Time Resolved Infrared Emission from Vibrational Excited Acetylene Following Super Energy Transfer Collisions with Hot Hydrogen  

NASA Astrophysics Data System (ADS)

Can a molecule be activated with large amounts of energy transferred in a single collision between an atom and a molecule? If so, this type of collision will greatly affect molecular reactivity and equilibrium in systems including combustion where abundant hot atoms exist. Conventional expectation of translation to vibration (T-V) energy transfer is that probability decreases exponentially with energy transferred. We show, however, that in collisions between a pair of atom/molecule for which chemical reactions may occur, such as between a hyperthermal H atom and an ambient acetylene molecule, (T-V) energy transfer occurs with surprisingly high efficiency through chemical complex formation. Time-resolved infrared emission observations reveal that collisions between H atoms moving with 60 kcal/mole energy and acetylene molecules result in transfer of up to 70% of this energy into vibrational degrees of freedom. These experimental results are further supported by state of the art quasi-classical trajectory calculations performed by Bowman and coworkers.

Smith, J. M.; Nikow, M.; Dai, J. Ma Andh. L.

2013-06-01

406

Vibrational energy transfer in laser-excited A2Sigma/+/ OH as a flame thermometer  

NASA Astrophysics Data System (ADS)

The paper surveys an experiment in which OH molecules in the burnt gases of a methane-air flame are excited to individual rotational levels of the v-prime = 0 level of the A2Sigma(+) state using a tunable pulsed laser, noting that some of the laser excited molecules undergo upward collisional energy transfer to v-prime = 1 before radiating. It is shown how the temperature of the flame is determined by a measurement of the ratio of the populations in these two vibrational levels, together with an estimate of the relative rates of vibrational transfer and quenching and the invocation of detailed balancing. It is concluded that the method should be suitable for the single-pulse simultaneous measurement of the temperature and the concentration of OH, a reactive intermediate species.

Crosley, D. R.; Smith, G. P.

1980-02-01

407

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

408

Pulsed Power Driven Fusion Energy  

SciTech Connect

Pulsed power is a robust and inexpensive technology for obtaining high powers. Considerable progress has been made on developing light ion beams as a means of transporting this power to inertial fusion capsules. However, further progress is hampered by the lack of an adequate ion source. Alternatively, z-pinches can efficiently convert pulsed power into thermal radiation, which can be used to drive an inertial fusion capsule. However, a z-pinch driven fusion explosion will destroy a portion of the transmission line that delivers the electrical power to the z-pinch. They investigate several options for providing standoff for z-pinch driven fusion. Recyclable Transmission Lines (RTLs) appear to be the most promising approach.

SLUTZ,STEPHEN A.

1999-11-22

409

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

410

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

411

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

PubMed Central

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.

Proctor, David L.; Davis, H. Floyd

2008-01-01

412

Fundamental study of an electric power transmission system for implanted medical devices using magnetic and ultrasonic energy.  

PubMed

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

413

Stabilization of peptide helices by length and vibrational free energies: Ab initio case study of polyalanine  

NASA Astrophysics Data System (ADS)

Helices are one of the most abundant secondary structure ``building blocks" of polypeptides and proteins. Here, we explore helix stabilization as a function of peptide length and temperature [harmonic approximation to the vibrational free energy (FE)], for the alanine-based peptide, Ac-Alan-LysH^+ n=4-15, in the gas phase. For n=4-8, we predict the lowest energy structures in density-functional theory, using the van der Waals (vdW) corrected[1] PBE exchange-correlation potential. ?-helices become the lowest energy structures at n 7-8 on the potential energy surface, but only barely and if including vdW interactions. At finite temperatures, the helices are further stabilized over compact conformers. While the vibrational entropy is the leading stabilizing term at 300 K, also the zero-point-energies favor the helical structures. For n>=8, the ?-helix should be the only accessible conformer in the FE surface at 300 K, in agreement with experiment[2] and with our own comparison[3] of calculated ab initio anharmonic IR spectra to experimental IR multiple photon dissociation data for n=5, 10, and 15. [1] Tkatchenko and Scheffler, PRL 102, 073055 (2009); [2] Kohtani and Jarrold, JACS 108, 8454 (2004); [3] Rossi et al., JPCL 1, 3465 (2010).

Rossi, Mariana; Blum, Volker; Scheffler, Matthias

2012-02-01

414

Fundamental study of an electric power transmission system for implanted medical devices using magnetic and ultrasonic energy  

Microsoft Academic Search

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

415

Nuclear power and energy planning.  

National Technical Information Service (NTIS)

With the rapid depletion of conventional energy sources such as coal and oil and the growing world demand for energy the question of how to provide the extra energy needed in the future is addressed. Relevant facts and figures are presented. Coal and oil ...

P. Jones

1990-01-01

416

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.